Solid-state alternating current limiting circuit and solid-state current controller device
Through the solid-state AC current limiting circuit, the current is controlled by using MOSFET switch tubes and other components, the problem that the thermistor cannot effectively control the inrush current due to temperature influence is solved, and flexible limit and protection of AC current is achieved, and the reliability and applicability of the system is improved.
Patent Information
- Application Number
- CN202411771769.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-04
- Publication Date
- 2025-02-25
AI Technical Summary
In the prior art, the thermistor is greatly affected by temperature and cannot effectively control the inrush current, resulting in the power consumption system not being started normally in a low-temperature environment. The too high temperature of the thermistor will shorten its life and affect the system reliability.
The solid-state AC current limiting circuit is adopted, and the MOSFET switch tube and multiple diodes, capacitors, resistors, and voltage regulators are used to control the conduction and disconnection of the MOSFET switch tube and detect the current voltage drop to limit and protect the AC current.
It realizes effective control of inrush current, avoids the problem of thermistor being affected by temperature, improves the reliability of the system and the flexibility of current limit in different environments, and is suitable for high-power occasions.
Smart Images
Figure CN119518598A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of electrical devices with single-phase AC input, in particular to a solid-state AC current limiting circuit and a solid-state current controller device. Background Art
[0002] For single-phase AC input electrical devices, such as power converters, there are high-voltage and large-capacity capacitors at the input end. When the input voltage suddenly changes after the power is turned on, the sudden change in voltage across the capacitor will cause surge current at the input end of the power system, causing EMI and EMC interference in the electronic system. At present, the method to reduce surge current is to connect a negative temperature coefficient thermistor RT1 (such as Figure 1 )To solve this problem, due to the negative temperature characteristics of the thermistor, its impedance is large at room temperature. When current flows through the resistor, the maximum current can be suppressed. When current flows through the resistor, the thermistor will heat up and its resistance value will decrease rapidly to ensure low loss during steady-state operation.
[0003] However, the disadvantages of using thermistors to solve the inrush current caused by the input end of the power supply system are also obvious. There are four main points: First, the thermistor works by using the physical property that thermistor impedance will decrease after the current passes through the thermistor to generate heat, so that the impedance is large when the system is turned on to reduce the inrush current, and the resistance is reduced after the system is working normally to reduce the loss. Its resistance is greatly affected by temperature, and the current suppression effect is affected by temperature and cannot be controlled. At the same time, when the thermistor is in a low-temperature cold state, the impedance value will increase to more than ten times the impedance value at normal temperature, causing the back-end power system to be unable to start normally in a short time when the external environment is low; the thermistor has a low impedance in a high-temperature hot state, and cannot achieve the effect of suppressing the inrush current. Second, the thermistor is in a hot state after the line is working normally. At this time, if there is a voltage mutation at the input end or it restarts after power failure, because the temperature of the thermistor itself has not yet returned to normal temperature, its resistance is small and cannot achieve the purpose of suppressing the inrush current. Third, when the thermistor is connected in series in the current loop, its own impedance will reduce the efficiency of the entire system. At the same time, if the temperature of the thermistor is too high, its own life will be greatly reduced. It is a major factor affecting the reliability of the entire system and cannot be used in circuits with higher power. Summary of the invention
[0004] In view of the problem in the prior art that thermistors are greatly affected by temperature and thus have a poor effect on suppressing surge current, the present invention provides a solid-state AC current limiting circuit and a solid-state current controller device.
[0005] The present invention is achieved through the following technical solutions: A solid-state AC current limiting circuit, comprising a MOSFET switch tube, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a current stabilizing tube Dz1, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4; The anode of the first diode D1 is connected to the first AC voltage input terminal 1P, the cathode is connected to one end of the first capacitor C1, and the other end of the first capacitor C1 is connected to the second AC voltage input terminal 2P and the second AC output terminal 4P; The anode of the second diode D2 is connected to the cathode of the first diode D1, the cathode is connected to one end of the second capacitor C2, and the source of the MOSFET switch is connected to the other end of the second capacitor C2; One end of the first resistor R1 is connected to the cathode of the second diode D2, the cathode of the voltage regulator tube Dz1 and the gate of the MOSFET switch tube are connected to the other end of the first resistor R1, the source of the MOSFET switch tube is connected to the anode of the voltage regulator tube Dz1, and the third capacitor C3 is connected in parallel with the voltage regulator tube Dz1; One end of the second resistor R2 is connected to the cathode of the voltage regulator tube Dz1, and the other end is connected to the cathode of the reference voltage source IC1, and the anode of the reference voltage source IC1 is connected to the anode of the voltage regulator tube Dz1; one end of the third resistor R3 is connected to the anode of the reference voltage source IC1, and the other end is connected to the reference pin of the reference voltage source IC1, and the fourth capacitor C4 is connected in parallel with the third resistor R3; One end of the fourth resistor R4 is connected to the reference pin of the reference voltage source IC1, and the other end is connected to the cathode of the third diode D3 and the cathode of the fourth diode D4. The anode of the third diode D3 is connected to the first AC voltage input terminal 1P, and the anode of the fourth diode D4 is connected to the first AC output terminal 3P.
[0006] Preferably, the resistance of the third resistor R3 is 100KΩ-200KΩ.
[0007] Preferably, the resistance of the third resistor R4 is 50% to 200% of the resistance of the third resistor R3.
[0008] Preferably, the withstand voltage of the MOSFET tube is higher than the amplitude of the input AC voltage.
[0009] Preferably, the MOSFET tube is an N-channel MOSFET tube.
[0010] Preferably, the MOSFET switch tube includes two MOSFET tubes, denoted as a first MOSFET tube T1 and a second MOSFET tube T2, the drain of the first MOSFET tube T1 is connected to the first AC voltage input terminal 1P, the drain of the second MOSFET tube T2 is connected to the first AC output voltage 3P, and the source of the first MOSFET tube T1 is connected to the source of the second MOSFET tube T2.
[0011] Preferably, the withstand voltage of the first capacitor C1 is higher than the amplitude of the input AC voltage.
[0012] Preferably, the withstand voltage of the second capacitor C2 is higher than twice the amplitude of the input AC voltage.
[0013] Preferably, the stable voltage of the voltage regulator tube Dz1 is 8V to 15V.
[0014] A solid-state current controller device comprising the solid-state AC current limiting circuit.
[0015] Compared with the prior art, the present invention has the following beneficial effects: In the solid-state AC current limiting circuit of the present invention, the magnitude of the input AC current is limited by controlling the on and off of MOSFET; at the same time, the current is detected when the MOSFET is turned on and the on resistance (R DS(ON) ) to detect the input current. (Note: R DS(ON)is the inherent parameter of the DS junction of the MOSFET tube), and its principle is as follows: a DC voltage is generated at both ends of the second capacitor C2 through a voltage doubling rectifier circuit composed of the first diode D1, the second diode D2, the first capacitor C1, and the second capacitor C2; a voltage stabilizing circuit is composed of the first resistor R1, the voltage stabilizing tube Dz1, and the third capacitor C3 to generate a stable DC voltage to drive the first MOSFET tube T1 and the second MOSFET tube T2 to turn on; due to the internal resistance of the MOSFET tube after turning on, when the current flows through the first MOSFET tube T1 and the second MOSFET tube T2, a voltage drop will be generated, and the voltage will enter the reference pin of the reference voltage source IC1 through the third diode D3, the fourth diode D4, and the voltage division of the third resistor R3 and the fourth resistor R4. When the voltage of the reference pin of the reference voltage source IC1 exceeds the set value, the cathode and anode inside the reference voltage source IC1 are turned on, and the gate voltage of the first MOSFET tube T1 and the second MOSFET tube T2 is pulled down through the second resistor R2, thereby turning off the first MOSFET tube T1 and the second MOSFET tube T2, disconnecting the line, and disconnecting the circuit. Until the input voltage amplitude decreases, the reference voltage terminal voltage of the reference voltage source IC1 is lower than the set value, the cathode and anode inside the reference voltage source IC1 are turned off, and the first MOSFET tube T1 and the second MOSFET tube T2 are turned on again, that is, the MOSFET is turned off immediately after the current exceeds the set value to prevent the current from exceeding the set value, which is determined by the resistance values of resistors R3 and R4, until the next cycle, to achieve cycle-by-cycle current limiting. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a circuit diagram of suppressing surge current by using a thermistor in the prior art; Figure 2 is a circuit diagram of a solid-state AC current limiting circuit of the present invention; Figure 3 It is a schematic diagram of a solid-state AC current limiting circuit of the present invention. DETAILED DESCRIPTION
[0017] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.
[0018] The present invention discloses a solid-state AC current limiting circuit, referring to Figure 2 , including a MOSFET switch tube, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a current-stabilizing tube Dz1, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4.
[0019] Among them, the anode of the first diode D1 is connected to the first AC voltage input terminal 1P, the cathode is connected to one end of the first capacitor C1, and the other end of the first capacitor C1 is connected to the second AC voltage input terminal 2P and the second AC output terminal 4P; the anode of the second diode D2 is connected to the cathode of the first diode D1, the cathode is connected to one end of the second capacitor C2, and the source of the MOSFET switch tube is connected to the other end of the second capacitor C2; one end of the first resistor R1 is connected to the cathode of the second diode D2, the cathode of the voltage regulator tube Dz1 and the gate of the MOSFET switch tube are both connected to the other end of the first resistor R1, the source of the MOSFET switch tube is connected to the anode of the voltage regulator tube Dz1, and the third capacitor C3 is connected to the cathode of the second diode D2. In parallel with the Zener tube Dz1; one end of the second resistor R2 is connected to the cathode of the Zener tube Dz1, and the other end is connected to the cathode of the reference voltage source IC1, and the anode of the reference voltage source IC1 is connected to the anode of the Zener tube Dz1; one end of the third resistor R3 is connected to the anode of the reference voltage source IC1, and the other end is connected to the reference pin of the reference voltage source IC1, and the fourth capacitor C4 is connected to the third resistor R3 in parallel; one end of the fourth resistor R4 is connected to the reference pin of the reference voltage source IC1, and the other end is connected to the cathode of the third diode D3 and the cathode of the fourth diode D4, the anode of the third diode D3 is connected to the first AC voltage input terminal 1P, and the anode of the fourth diode D4 is connected to the first AC output terminal 3P.
[0020] Among them, the resistance value of the third resistor R3 is 100KΩ~200KΩ, and the resistance value of the third resistor R4 is 50%~200% of the resistance value of the third resistor R3. The specific resistance value is determined by the current limit size set by the circuit, making the current limit more flexible.
[0021] The withstand voltage of the MOSFET tube is higher than the amplitude of the input AC voltage, and the MOSFET tube is an N-channel MOSFET tube, which is to ensure the safety of the circuit.
[0022] The MOSFET switch tube includes two MOSFET tubes, which are recorded as a first MOSFET tube T1 and a second MOSFET tube T2. The drain of the first MOSFET tube T1 is connected to the first AC voltage input terminal 1P, the drain of the second MOSFET tube T2 is connected to the first AC output voltage 3P, and the source of the first MOSFET tube T1 is connected to the source of the second MOSFET tube T2.
[0023] The withstand voltage of the first capacitor C1 is higher than the amplitude of the input AC voltage, and the withstand voltage of the second capacitor C2 is higher than twice the amplitude of the input AC voltage, so as to ensure the stable operation of the capacitor in the circuit.
[0024] The stable voltage of the voltage regulator Dz1 is 8V~15V, which can not only protect the MOSFET switch tube, but also ensure the normal operation of the circuit.
[0025] A solid-state AC current limiting circuit of the present invention has a MOSFET switch tube as the core, and cooperates with multiple diodes, capacitors, resistors and voltage regulator tubes to achieve effective limitation and protection of AC current. It has the advantages of simple structure, low cost, easy implementation and flexible current limitation, and can be widely used in AC circuits that require current protection. Specifically, the first diode D1 is connected between the first AC voltage input terminal 1P and the first capacitor C1 to guide AC power into the circuit. The second diode D2 is connected in series with the first diode D1 and is connected to the source of the MOSFET switch tube through the second capacitor C2 to form a current path. The first capacitor C1 acts as a filter capacitor to smooth the input voltage. The second capacitor C2 cooperates with the MOSFET switch tube to achieve voltage conversion and isolation. The third capacitor C3 is connected in parallel with the voltage regulator tube Dz1 to stabilize the gate voltage. The fourth capacitor C4 is connected in parallel with the third resistor R3 to provide a stable working condition for the reference voltage source. The first resistor R1 is connected to the gate of the second diode D2, the voltage regulator tube Dz1 and the MOSFET switch tube to control the gate voltage. The voltage regulator Dz1 ensures that the gate voltage does not exceed its stable voltage to protect the MOSFET switch. The second resistor R2, the third resistor R3 and the fourth resistor R4 cooperate with the reference voltage source IC1 to set the current limit threshold.
[0026] The present invention also discloses a solid-state current controller device, referring to Figure 3 , its 3rd and 4th pins are connected in series to the power part circuit of the system, and the 1st and 2nd pins are directly connected to the power input terminal, regardless of polarity. The principle of the solid-state AC current limiting circuit of the present invention is as follows: by detecting the current to control the on and off of the internal MOSFET tube T1 and MOSFET tube T2, when the current passing through the solid-state current controller exceeds the set value, the MOSFET tube T1 and MOSFET tube T2 are turned off to block the current from passing until the input voltage amplitude drops to zero, and then the MOSFET tube T1 and MOSFET tube T2 are turned on again to allow the current to pass. The advantages of this device are mainly the following three points: First, the maximum input current is controllable, and its current is determined by the on-resistance (R DS(ON) ), the resistance values of resistors R3 and R4, and the internal reference voltage of the reference voltage source IC1. It is less affected by the external ambient temperature and has a wide operating temperature range. It has been verified by tests that it can work in the range of -55℃ to 105℃; secondly, once the input current exceeds the allowable range, the input is immediately disconnected, avoiding the problem that other solutions cannot suppress surge current in the event of a sudden change in input voltage or restart after power failure; thirdly, under normal working conditions, the internal MOSFET tube is in the on state, the loss in the circuit is very low, and the circuit can work in high-power occasions. The present invention does not use mechanical components such as relays as a whole, has the advantages of small size, high reliability and long life, and has been verified by product batch production and can be used to suppress the starting impact current of the motor.
[0027] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and substitutions, and these modifications and substitutions are also within the scope of protection covered by the claims.
Claims
1. A solid-state AC current limiting circuit, characterized in that: Including MOSFET switch tube, first diode D1, second diode D2, third diode D3, fourth diode D4, first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C4, current stabilizing tube Dz1, first resistor R1, second resistor R2, third resistor R3, fourth resistor R4; The anode of the first diode D1 is connected to the first AC voltage input terminal 1P, the cathode is connected to one end of the first capacitor C1, and the other end of the first capacitor C1 is connected to the second AC voltage input terminal 2P and the second AC output terminal 4P; The anode of the second diode D2 is connected to the cathode of the first diode D1, the cathode is connected to one end of the second capacitor C2, and the source of the MOSFET switch is connected to the other end of the second capacitor C2; One end of the first resistor R1 is connected to the cathode of the second diode D2, the cathode of the voltage regulator tube Dz1 and the gate of the MOSFET switch tube are connected to the other end of the first resistor R1, the source of the MOSFET switch tube is connected to the anode of the voltage regulator tube Dz1, and the third capacitor C3 is connected in parallel with the voltage regulator tube Dz1; One end of the second resistor R2 is connected to the cathode of the voltage regulator tube Dz1, and the other end is connected to the cathode of the reference voltage source IC1, and the anode of the reference voltage source IC1 is connected to the anode of the voltage regulator tube Dz1; One end of the third resistor R3 is connected to the anode of the reference voltage source IC1, and the other end is connected to the reference pin of the reference voltage source IC1, and the fourth capacitor C4 is connected in parallel with the third resistor R3; One end of the fourth resistor R4 is connected to the reference pin of the reference voltage source IC1, and the other end is connected to the cathode of the third diode D3 and the cathode of the fourth diode D4. The anode of the third diode D3 is connected to the first AC voltage input terminal 1P, and the anode of the fourth diode D4 is connected to the first AC output terminal 3P.
2. The solid-state AC current limiting circuit according to claim 1, characterized in that: The resistance of the third resistor R3 is 100KΩ to 200KΩ.
3. The solid-state AC current limiting circuit according to claim 2, characterized in that: The resistance of the third resistor R4 is 50% to 200% of the resistance of the third resistor R3.
4. The solid-state AC current limiting circuit according to claim 1, characterized in that: The withstand voltage of the MOSFET tube is higher than the amplitude of the input AC voltage.
5. The solid-state AC current limiting circuit according to claim 1, characterized in that: The MOSFET tube is an N-channel MOSFET tube.
6. The solid-state AC current limiting circuit according to claim 1, characterized in that: The MOSFET switch tube includes two MOSFET tubes, which are recorded as a first MOSFET tube T1 and a second MOSFET tube T2. The drain of the first MOSFET tube T1 is connected to the first AC voltage input terminal 1P, the drain of the second MOSFET tube T2 is connected to the first AC output voltage 3P, and the source of the first MOSFET tube T1 is connected to the source of the second MOSFET tube T2.
7. The solid-state AC current limiting circuit according to claim 1, characterized in that: The withstand voltage of the first capacitor C1 is higher than the amplitude of the input AC voltage.
8. The solid-state AC current limiting circuit according to claim 1, characterized in that: The second capacitor C2 has a withstand voltage higher than twice the amplitude of the input AC voltage.
9. The solid-state AC current limiting circuit according to claim 1, characterized in that: The stable voltage of the voltage regulator Dz1 is 8V~15V.
10. A solid-state current controller device comprising the solid-state AC current limiting circuit according to any one of claims 1 to 9.