Isolated undervoltage and overvoltage detection circuit
By using an isolated undervoltage and overvoltage detection circuit, and combining chip U12 and optocoupler U13, low-cost and fast overvoltage and undervoltage detection is achieved, solving the problem of high cost of traditional detection circuits.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2026-03-13
AI Technical Summary
Traditional overvoltage and undervoltage detection circuits require two microcontrollers, resulting in high economic costs.
An isolated undervoltage and overvoltage detection circuit is adopted, including a voltage divider module, a comparator module, an isolation module and an output module. Chip U12 is used as a voltage reference and comparator, and optocoupler U13 provides isolation function, eliminating the need for the primary power supply circuit.
It achieves low-cost overvoltage and undervoltage detection, has rapid detection capabilities, and also has isolation functions.
Smart Images
Figure CN223993556U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of electrical protection technology, specifically to an isolated undervoltage and overvoltage detection circuit. Background Technology
[0002] Currently, electrical equipment has high requirements for the working power supply during use. If the voltage of the power grid is too high or high-power equipment is started, the load will change drastically, causing the power supply voltage to fluctuate. If this voltage is supplied to the electrical equipment for a long time, it will cause great damage to the electrical equipment. Therefore, it is necessary to set up overvoltage and undervoltage detection circuits to ensure that the electrical equipment is used under normal power supply conditions.
[0003] Traditional overvoltage and undervoltage detection circuits often use two microcontrollers to work together to generate and receive PWM signals, thereby detecting whether the circuit is in an overvoltage or undervoltage state. However, using this structure for overvoltage and undervoltage detection circuits results in high economic costs.
[0004] Therefore, there is an urgent need for a low-cost undervoltage and overvoltage detection circuit. Utility Model Content
[0005] To overcome the problems existing in the prior art, the purpose of this utility model is to provide an isolated undervoltage and overvoltage detection circuit.
[0006] To achieve the above objectives, this utility model provides the following technical solution: an isolated undervoltage and overvoltage detection circuit, comprising a voltage divider module, a comparator module, an isolation module, and an output module; the voltage divider module is connected to the input terminals of the comparator module and the isolation module respectively, the output terminal of the comparator module is connected to the input terminal of the isolation module, and the output terminal of the isolation module is connected to the output module; the voltage divider module includes a first voltage divider module and a second voltage divider module.
[0007] The present invention is further configured such that: the first voltage divider module includes resistors R96, R103, R104, and R105; the first end of resistor R105 is connected to the input voltage, the second end of resistor R105 is connected to the first end of resistor R103, the second end of resistor R103 is connected to the first end of resistor R104, the second end of resistor R104 is connected to the first end of resistor R96 and the comparison module respectively, and the second end of resistor R96 is connected to the protective ground.
[0008] The present invention is further configured such that: the comparison module includes a chip U12 and a capacitor C81; the reference terminal of the chip U12 is connected to the second terminal of the resistor R104; the reference terminal of the chip U12 is also connected to the first terminal of the capacitor C81; the second terminal of the capacitor C81 is connected to the protective ground; the cathode of the chip U12 is connected to the protective ground; and the anode of the chip U12 is connected to the isolation module.
[0009] The present invention is further configured such that: the second voltage divider module includes resistors R100, R101, and R102; the first end of resistor R100 is connected to the input voltage; the second end of resistor R100 is connected to the first end of resistor R101; the second end of resistor R101 is connected to the first end of resistor R102 and the isolation module respectively; and the second end of resistor R102 is grounded.
[0010] The present invention is further configured such that: the isolation module includes an optocoupler U13, the optocoupler U13 includes a light-emitting diode and a phototransistor, the anode of the light-emitting diode is connected to the resistor R102, the cathode of the light-emitting diode is connected to the anode of the chip U12, the emitter of the phototransistor is connected to digital ground, and the collector of the phototransistor is connected to the output module.
[0011] The present invention is further configured such that: the output module includes a resistor R99, a capacitor C80 and a control unit; the first end of the resistor R99 is connected to the collector of the phototransistor, and the second end of the resistor R99 is connected to the power supply voltage; the collector of the phototransistor is also connected to the first end of the capacitor C80 and the control unit respectively, and the second end of the capacitor C80 is connected to digital ground.
[0012] The present invention is further configured such that: the capacitor C81, together with resistors R96, R103, R104 and R105, constitute a low-pass filter, and the value of capacitor C81 is obtained according to the required RC constant.
[0013] The present invention is further configured such that the value of resistor R99 is required to ensure that optocoupler U13 can output a low level under the condition of minimum transmission ratio.
[0014] In this invention, the voltage divider module is used for power supply and providing input voltage. The comparison module is used to respond to the input voltage and output a signal, and transmit the signal to the isolation module. The isolation module is used to transmit the signal to the output module when it is turned on. Depending on the setting of the comparison threshold, it can be used as an undervoltage detection signal or an overvoltage detection signal to detect whether the circuit is in an overvoltage or undervoltage state.
[0015] Compared with the prior art, the present invention has the following beneficial effects:
[0016] In this invention, chip U12 serves as both a voltage reference and a comparator, while optocoupler U13 provides isolation and performs level conversion. The primary side supplies power to optocoupler U13 and chip U12 via resistors R100, R101, and R102. The primary side provides input voltage to the comparator module via resistors R96, R103, R104, and R105. This invention features isolation, enabling rapid detection of overvoltage or undervoltage conditions in the circuit, and eliminates the need for a primary side power supply circuit, resulting in low cost. Attached Figure Description
[0017] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a circuit diagram of the isolated undervoltage and overvoltage detection circuit described in the embodiment. Detailed Implementation
[0019] The technical solution of this utility model will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are not all embodiments of this utility model. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0020] Example:
[0021] like Figure 1 As shown, a preferred embodiment of the present invention is provided, an isolated undervoltage and overvoltage detection circuit, including a voltage divider module, a comparator module, an isolation module, and an output module; the voltage divider module is connected to the input terminals of the comparator module and the isolation module respectively, the output terminal of the comparator module is connected to the input terminal of the isolation module, and the output terminal of the isolation module is connected to the output module; the voltage divider module includes a first voltage divider module and a second voltage divider module.
[0022] In this embodiment, the comparison threshold is AC 189V RMS / DC 267V.
[0023] The first voltage divider module includes resistors R96, R103, R104, and R105; the first end of resistor R105 is connected to the input voltage AC_DET_L, the second end of resistor R105 is connected to the first end of resistor R103, the second end of resistor R103 is connected to the first end of resistor R104, the second end of resistor R104 is connected to the first end of resistor R96 and the comparator module, and the second end of resistor R96 is connected to protective ground.
[0024] The comparison module includes chip U12 and capacitor C81. In this embodiment, chip U12 is a KIA431A chip, which serves as both a voltage reference and a comparator. The reference terminal of chip U12 is connected to the second terminal of resistor R104, and the reference terminal of chip U12 is also connected to the first terminal of capacitor C81. The second terminal of capacitor C81 is connected to protective ground. The cathode of chip U12 is connected to protective ground, and the anode of chip U12 is connected to the isolation module.
[0025] The capacitor C81, together with resistors R96, R103, R104 and R105, constitutes a low-pass filter. The value of capacitor C81 is obtained according to the required RC constant.
[0026] The second voltage divider module includes resistors R100, R101, and R102. The first end of resistor R100 is connected to the input voltage AC_DET_L, the second end of resistor R100 is connected to the first end of resistor R101, the second end of resistor R101 is connected to the first end of resistor R102 and the isolation module, and the second end of resistor R102 is grounded.
[0027] The isolation module includes an optocoupler U13. In this embodiment, an EL817S1(C)(TU)-F optocoupler is used. The optocoupler U13 includes a light-emitting diode (LED) and a phototransistor. The anode of the LED is connected to the resistor R102, and the cathode of the LED is connected to the anode of the chip U12. The emitter of the phototransistor is connected to digital ground, and the collector of the phototransistor is connected to the output module to send the output signal AC220_Undervoltage.
[0028] The output module includes a resistor R99, a capacitor C80, and a control unit. The first terminal of resistor R99 is connected to the collector of the phototransistor, and the second terminal is connected to the power supply voltage. The collector of the phototransistor is also connected to the first terminal of capacitor C80 and the control unit, and the second terminal of capacitor C80 is connected to digital ground. The value of resistor R99 must ensure that optocoupler U13 can output a reliable low level under the condition of minimum transmission ratio.
[0029] In actual use, when the input voltage AC_DET_L exceeds the threshold of 267V, the input voltage at the reference terminal of chip U12 will exceed the comparator reference voltage Vref (2.5V), causing current to flow between the cathode and anode of chip U12. This current flows through the LED of optocoupler U13, causing it to emit light, which in turn turns on the phototransistor of U13, and the output signal AC220_Undervoltage becomes low. Conversely, when the input voltage AC_DET_L is below the threshold of 267V, the output signal AC220_Undervoltage becomes high.
[0030] The above technical features constitute the preferred embodiment of this utility model, which has strong adaptability and optimal implementation effect. Non-essential technical features can be added or removed according to actual needs to meet the needs of different situations.
[0031] Finally, it should be noted that the above content is only used to illustrate the technical solution of this utility model, and is not intended to limit the scope of protection of this utility model. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of this utility model do not depart from the essence and scope of the technical solution of this utility model.
Claims
1. An isolated under- and over-voltage detection circuit, characterized by The application relates to a voltage protection circuit, which comprises a voltage dividing module, a comparison module, an isolation module and an output module; the voltage dividing module is connected with the input ends of the comparison module and the isolation module, the output end of the comparison module is connected with the input end of the isolation module, and the output end of the isolation module is connected with the output module; the voltage dividing module comprises a first voltage dividing module and a second voltage dividing module. The first voltage dividing module comprises resistors R96, R103, R104 and R105; the first end of the resistor R105 is connected with an input voltage, the second end of the resistor R105 is connected with the first end of the resistor R103, the second end of the resistor R103 is connected with the first end of the resistor R104, the second end of the resistor R104 is connected with the first end of the resistor R96 and the comparison module, and the second end of the resistor R96 is connected with a protective ground. The comparison module comprises a chip U12 and a capacitor C81; the reference end of the chip U12 is connected with the second end of the resistor R104, the reference end of the chip U12 is also connected with the first end of the capacitor C81, and the second end of the capacitor C81 is connected with the protective ground; the cathode of the chip U12 is connected with the protective ground, and the anode of the chip U12 is connected with the isolation module.
2. The isolated under- and over-voltage detection circuit according to claim 1, characterized in that The second voltage dividing module comprises resistors R100, R101 and R102; the first end of the resistor R100 is connected with the input voltage, the second end of the resistor R100 is connected with the first end of the resistor R101, the second end of the resistor R101 is connected with the first end of the resistor R102 and the isolation module, and the second end of the resistor R102 is connected with the ground.
3. The isolated undervoltage overvoltage detection circuit according to claim 2, characterized in that, The isolation module comprises an optical coupler U13, the optical coupler U13 comprises a light-emitting diode and a phototriode, the anode of the light-emitting diode is connected with the resistor R102, the cathode of the light-emitting diode is connected with the anode of the chip U12, the emitter of the phototriode is connected with a digital ground, and the collector of the phototriode is connected with the output module.
4. The isolated under- and over-voltage detection circuit according to claim 3, characterized in that The output module comprises a resistor R99, a capacitor C80 and a control unit; the first end of the resistor R99 is connected with the collector of the phototriode, and the second end of the resistor R99 is connected with a power supply voltage; the collector of the phototriode is also connected with the first end of the capacitor C80 and the control unit, and the second end of the capacitor C80 is connected with the digital ground.
5. The isolated under- and over-voltage detection circuit of claim 1, wherein The capacitor C81, the resistor R96, the resistor R103, the resistor R104 and the resistor R105 form a low-pass filter, and the value of the capacitor C81 is obtained according to the required RC constant.
6. The isolated under- and over-voltage detection circuit of claim 4, wherein The value of the resistor R99 needs to ensure that the optical coupler U13 can output a low level under the condition of the minimum transmission ratio.