Power supply circuit with current detection function, current detection circuit and electronic overload protection system
By introducing an overpower protection module into the current detection circuit, the problem of the current detection circuit being unable to disconnect the circuit under overload is solved, realizing shunt protection for the power module and improving the service life of the equipment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHEJIANG CHINT ELECTRIC CO LTD
- Filing Date
- 2025-01-21
- Publication Date
- 2026-04-28
AI Technical Summary
In the existing technology, the current detection circuit cannot effectively control the relay circuit to disconnect when overloaded, causing the power module to continuously receive a large current, generating a lot of heat and reducing its service life.
Design a power supply circuit with current detection, including a current sampling module, an over-power protection module, and a power supply module. The over-power protection module conducts when the current exceeds a preset threshold, diverting the power supply module and reducing heat generation.
This effectively reduces the risk of the power module burning out and extends its service life.
Smart Images
Figure CN224177912U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of electronic circuit technology, specifically to a power supply circuit with current detection, a current detection circuit, and an electronic overload protection system. Background Technology
[0002] The electronic overload protection system includes a current detection circuit and a relay circuit. When the current detection circuit detects an overload in the circuit containing the current to be measured, it drives the relay circuit to disconnect the circuit, thereby achieving overload protection.
[0003] In a current detection circuit, the power supply module typically powers the main control module based on the current from the current sampling module. The signal conditioning module collects the current from the current sampling module and outputs a corresponding voltage to the main control module. After the main control module is powered on, it can determine whether an overload has occurred based on the collected voltage, and then control the relay circuit accordingly. If an overload occurs and the corresponding circuit cannot be disconnected via the relay circuit, the power supply module in the current detection circuit will continuously receive a large current, generating a significant amount of heat. Prolonged operation in this condition can easily lead to burnout, ultimately reducing its lifespan. Utility Model Content
[0004] In view of the shortcomings of the existing technology, this utility model provides a power supply circuit with current detection, a current detection circuit and an electronic overload protection system.
[0005] In one embodiment, the present invention provides a power supply circuit with current detection, which includes a current sampling module, an over-power protection module, and a power supply module.
[0006] The power supply module and the current sampling module are used for electrical connection with the main control module, and are used to supply power to the main control module according to the current on the current sampling module;
[0007] The overpower protection module is electrically connected to the power supply module and is used to conduct when the current on the current sampling module exceeds a preset current threshold in order to shunt the power supply module.
[0008] In one embodiment, the overpower protection module includes a trigger resistor and a switching unit;
[0009] The trigger resistor, current sampling module, and power supply module are connected in series. The trigger resistor is also electrically connected to the controlled terminal of the switching unit, and is used to output a trigger signal to the switching unit when the current on the current sampling module exceeds a preset current threshold.
[0010] The first and second access terminals of the switching unit are connected in parallel with the power supply unit and are used to conduct when a trigger signal is received, so as to shunt the power supply module.
[0011] In one embodiment, the switching unit includes a PNP transistor;
[0012] The emitter of the PNP transistor is electrically connected to the first terminal of the trigger resistor, the base of the PNP transistor is electrically connected to the second terminal of the trigger resistor and the first input terminal of the power module, and the collector of the PNP transistor is electrically connected to the second input terminal of the power module.
[0013] In one embodiment, the switching unit further includes a first base resistor;
[0014] The first end of the first base resistor is electrically connected to the second end of the trigger resistor and the first input terminal of the power module, respectively, and the second end of the first base resistor is electrically connected to the base of the PNP transistor.
[0015] In one embodiment, the switching unit includes a PNP transistor and an NPN transistor;
[0016] The emitter of the PNP transistor is electrically connected to the first terminal of the trigger resistor and the collector of the NPN transistor, respectively. The base of the PNP transistor is electrically connected to the second terminal of the trigger resistor and the first input terminal of the power module, respectively. The collector of the PNP transistor is electrically connected to the base of the NPN transistor, and the emitter of the NPN transistor is electrically connected to the second input terminal of the power module.
[0017] In one embodiment, the switching unit further includes a first base resistor and / or a second base resistor;
[0018] The first terminal of the first base resistor is electrically connected to the second terminal of the trigger resistor and the first input terminal of the power module, respectively; the second terminal of the first base resistor is electrically connected to the base of the PNP transistor; and / or,
[0019] The first end of the second base resistor is electrically connected to the collector of the PNP transistor, and the second end of the second base resistor is electrically connected to the base of the NPN transistor.
[0020] Secondly, in one embodiment, the present invention provides a current detection circuit, which includes a main control module, a signal conditioning module, and a power supply circuit with current detection as described in any of the above embodiments.
[0021] The signal conditioning module is electrically connected to both the current sampling module and the main control module. It is used to collect the current from the current sampling module and output the corresponding collected voltage to the main control module.
[0022] In one embodiment, there are three current sampling modules and three signal conditioning modules;
[0023] Each current sampling module is used to sample the corresponding phase current of the three-phase motor;
[0024] The input terminal of the power supply module is electrically connected to each current sampling module, and the output terminal of the power supply module is electrically connected to the main control module.
[0025] Each signal conditioning module is electrically connected to its corresponding current sampling module and main control module.
[0026] In one embodiment, the current sampling module includes a current transformer, a rectifier bridge, and a sampling resistor; the power supply module includes a Zener diode; and the signal conditioning module includes an operational amplifier.
[0027] The first terminal of the current transformer is electrically connected to the first input terminal of the rectifier bridge, and the second terminal of the current transformer is electrically connected to the second input terminal of the rectifier bridge.
[0028] The first output terminal of the rectifier bridge is electrically connected to the cathode of the Zener diode and the power supply terminal of the main control module, respectively. The anode of the Zener diode is electrically connected to the first terminal of the sampling resistor and the non-inverting input terminal of the operational amplifier, respectively. The second output terminal of the rectifier bridge is electrically connected to the second terminal of the sampling resistor and the inverting input terminal of the operational amplifier, respectively. The output terminal of the operational amplifier is electrically connected to the acquisition terminal of the main control module.
[0029] In one embodiment, the power module further includes a buck regulator chip;
[0030] The input terminal of the buck regulator chip is electrically connected to the cathode of the Zener diode, the ground terminal of the buck regulator chip is electrically connected to the anode of the Zener diode, and the output terminal of the buck regulator chip is electrically connected to the power supply terminal of the main control module.
[0031] Thirdly, in one embodiment, the present invention provides an electronic overload protection system, which includes a relay circuit and a current detection circuit as described in any of the above embodiments.
[0032] The relay circuit is electrically connected to the main control module and is used to control the circuit containing the current sampled by the current sampling module to disconnect according to the overload drive signal output by the main control module.
[0033] By incorporating the aforementioned power supply circuit with current detection, current detection circuit, and electronic overload protection system, an overpower protection module is installed. Utilizing the protection function of the overpower protection module, it can conduct when the current on the current sampling module exceeds a preset current threshold, thereby diverting current to the power supply module, reducing the generated heat, thus lowering the risk of burnout, and ultimately extending its service life. Attached Figure Description
[0034] To more clearly illustrate the technical solutions in the embodiments of this utility model, the 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.
[0035] Figure 1 This is a schematic diagram of the current detection circuit in one embodiment of the present invention;
[0036] Figure 2 This is a schematic diagram of an overpower protection module including a trigger resistor and a switching unit in one embodiment of the present invention;
[0037] Figure 3 This is a schematic diagram of a switching unit including a PNP transistor and a first base resistor in one embodiment of the present invention;
[0038] Figure 4 This is a schematic diagram showing that, in one embodiment of the present invention, the switching unit further includes a PNP transistor and a second base resistor;
[0039] Figure 5 This is a schematic diagram showing that, in one embodiment of the present invention, three current sampling modules and three signal conditioning modules are respectively provided;
[0040] Figure 6 This is a schematic diagram showing the specific circuit implementation of the current sampling module, signal conditioning module, over-power protection module, and power supply module in one embodiment of the present invention.
[0041] Figure 7 This is a schematic diagram of the electronic overload protection system in one embodiment of the present invention;
[0042] Figure 8 This is a schematic diagram of the specific circuit implementation of the relay circuit in one embodiment of the present invention. Detailed Implementation
[0043] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.
[0044] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified. In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to implement and use this invention. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this invention can be implemented without using these specific details. In other instances, well-known structures and processes will not be described in detail to avoid obscuring the description of this invention with unnecessary detail. Therefore, this invention is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.
[0045] Firstly, such as Figure 1 As shown, in one embodiment, the present invention provides a power supply circuit with current detection, including a current sampling module, a signal conditioning module, an over-power protection module, a power supply module, and a main control module.
[0046] The current sampling module, over-power protection module, and power supply module constitute the power supply circuit for current sampling, which is used to power the main control module.
[0047] The power supply module is electrically connected to both the current sampling module and the main control module, and is used to supply power to the main control module based on the current from the current sampling module.
[0048] The power supply module is used to perform relevant power processing based on the current on the current sampling module to obtain a voltage suitable for powering the main control module, and then outputs the voltage to the main control module to power the main control module.
[0049] The specific structure of the power supply module depends on the current type on the current sampling module. If the current type on the current sampling module is DC, the power supply module only needs to include devices for purposes such as voltage reduction. If the current type on the current sampling module is AC, the power supply module needs to include devices for purposes such as voltage reduction as well as devices for rectification.
[0050] The signal conditioning module is electrically connected to both the current sampling module and the main control module. It is used to collect the current from the current sampling module and output the corresponding collected voltage to the main control module.
[0051] Since the current on the current sampling module cannot be directly obtained by the main control module, the current signal needs to be converted through the signal conditioning module to realize the current acquisition and obtain the corresponding acquisition voltage, which can be obtained by the main control module.
[0052] The acquisition voltage obtained by the main control module can characterize the current magnitude on the current sampling module. Therefore, the main control module can determine whether the circuit containing the measured current sampled by the current sampling module is overloaded by the acquisition voltage magnitude, thus achieving the ultimate goal of current detection.
[0053] The overpower protection module is electrically connected to the power supply module and is used to conduct when the current on the current sampling module exceeds a preset current threshold in order to shunt the power supply module.
[0054] The overpower protection module needs to conduct when the current in the current sampling module exceeds a preset current threshold. Therefore, the overpower protection module needs to have two functions: first, to sense the current in the current sampling module, and second, to trigger conduction when the current exceeds the preset current threshold.
[0055] By using the aforementioned current detection circuit and setting up an overpower protection module, the overpower protection module can conduct when the current on the current sampling module exceeds a preset current threshold, thereby diverting current to the power module, reducing the generated heat, reducing the risk of burnout, and thus improving service life.
[0056] like Figure 2 As shown, in one embodiment, the overpower protection module includes a trigger resistor R26 and a switching unit.
[0057] The trigger resistor R26, the current sampling module, and the power supply module are connected in series. The trigger resistor R26 is also electrically connected to the controlled terminal of the switching unit, and is used to output a trigger signal to the switching unit when the current on the current sampling module exceeds the preset current threshold.
[0058] In this embodiment, the current flowing through the trigger resistor R26 in the current sampling module creates a voltage drop across the trigger resistor R26. In this embodiment, the trigger resistor R26 is used to output a trigger signal to the switching unit when the current exceeds a preset current threshold. Essentially, it provides the switching unit with a trigger voltage exceeding a preset voltage threshold when the current exceeds the preset current threshold. This trigger voltage enables the switching unit to conduct.
[0059] The first and second access terminals of the switching unit are connected in parallel with the power supply unit and are used to conduct when a trigger signal is received, so as to shunt the power supply module.
[0060] When the switching unit is turned on, the trigger resistor R26 and the power supply module form the first current branch, and the switching unit forms the second current branch. The current on the current sampling module flows through both the first and second current branches. Since the current on the current sampling module is constant, the second current branch formed after the switching unit is turned on will divert some current, making the current on the first current branch formed by the trigger resistor R26 and the power supply module smaller than the current on the current sampling module.
[0061] like Figure 3 As shown, in one embodiment, the switching unit includes a PNP transistor Q3.
[0062] The emitter of the PNP transistor Q3 is electrically connected to the first terminal of the trigger resistor R26. The base of the PNP transistor Q3 is electrically connected to the second terminal of the trigger resistor R26 and the first input terminal of the power module. The collector of the PNP transistor Q3 is electrically connected to the second input terminal of the power module.
[0063] It should be noted that, since the essence of this application is to control the current connected to the power module, the triggering condition is that the current on the current sampling module exceeds the preset current threshold. The basis for this is that the voltage across the trigger resistor R26 exceeds the bias voltage of the PNP transistor Q3. Therefore, it is necessary to reasonably select the resistance value of the trigger resistor R26 and the bias voltage of the PNP transistor Q3 based on the preset current threshold to ensure that the purpose of shunting the power module can be reliably achieved.
[0064] like Figure 3 As shown, in one embodiment, the switching unit further includes a first base resistor R27.
[0065] The first end of the first base resistor R27 is electrically connected to the second end of the trigger resistor R26 and the first input terminal of the power module, respectively. The second end of the first base resistor R27 is electrically connected to the base of the PNP transistor Q3.
[0066] The first base resistor R27 serves to limit current, stabilize bias, prevent overdrive, and match input impedance, so as to better drive the PNP transistor Q3.
[0067] like Figure 4 As shown, in one embodiment, the switching unit includes a pnp transistor Q3 and an npn transistor Q4.
[0068] The emitter of the PNP transistor Q3 is electrically connected to the first terminal of the trigger resistor R26 and the collector of the NPN transistor Q4, respectively. The base of the PNP transistor Q3 is electrically connected to the second terminal of the trigger resistor R26 and the first input terminal of the power supply module, respectively. The collector of the PNP transistor Q3 is electrically connected to the base of the NPN transistor Q4, and the emitter of the NPN transistor Q4 is electrically connected to the second input terminal of the power supply module.
[0069] Specifically, when the current on the current sampling module exceeds the preset current threshold, the voltage across the trigger resistor R26 exceeds the preset voltage threshold, satisfying the bias voltage of the PNP transistor Q3, causing the PNP transistor Q3 to conduct, thereby pulling up the base voltage of the NPN transistor Q4, and turning on the NPN transistor Q4.
[0070] The simultaneous use of PNP transistor Q3 and NPN transistor Q4 enables drive amplification, resulting in higher voltage withstand capability and better control of the current in the current sampling module.
[0071] like Figure 4 As shown, in one embodiment, the switching unit further includes a first base resistor R27 and a second base resistor R28.
[0072] The first terminal of the first base resistor R27 is electrically connected to the second terminal of the trigger resistor R26 and the first input terminal of the power module, respectively. The second terminal of the first base resistor R27 is electrically connected to the base of the PNP transistor Q3. The first terminal of the second base resistor R28 is electrically connected to the collector of the PNP transistor Q3. The second terminal of the second base resistor R28 is electrically connected to the base of the NPN transistor Q4.
[0073] The second base resistor R28 has the same function as the first base resistor R27, which can limit the current, stabilize the bias, prevent overdrive and match the input impedance, so as to better drive the npn transistor Q4.
[0074] In other embodiments, only one of the first base resistor R27 and the second base resistor R28 may be provided.
[0075] like Figure 5As shown, in one embodiment, there are three current sampling modules and three signal conditioning modules.
[0076] Each current sampling module is used to sample the corresponding phase current of the three-phase motor.
[0077] The input terminal of the power supply module is electrically connected to each current sampling module, and the output terminal of the power supply module is electrically connected to the main control module.
[0078] Since the input terminals of the power supply module are electrically connected to each current sampling module, the current connected to the power supply module is essentially the sum of the currents output by each of the multiple current sampling modules. However, it's important to note that because each current sampling module samples the current of a corresponding phase of the three-phase motor, and the currents of the three phases of the motor are currents with different phases but the same frequency and amplitude, the total current connected to the power supply module remains a stable current varying with a certain frequency and amplitude. Therefore, this does not affect the shunt protection function of the power supply module.
[0079] Each signal conditioning module is electrically connected to its corresponding current sampling module and main control module.
[0080] Although the power module receives the total current after aggregation, each signal conditioning module only forms a sampling loop with its corresponding current sampling module. For each signal conditioning module, it can only sample the current from its corresponding current sampling module; the current from other current sampling modules will not affect the sampling accuracy of that signal conditioning module.
[0081] like Figure 6 As shown, in one embodiment, the first current sampling module includes a current transformer T1, a rectifier bridge D2, and a sampling resistor R2; the second current sampling module includes a current transformer T2, a rectifier bridge D3, and a sampling resistor R8; the third current sampling module includes a current transformer T3, a rectifier bridge D4, and a sampling resistor R16; the power supply module includes a Zener diode ZD1 and a buck regulator chip U1; the first signal conditioning module includes an operational amplifier U3B; the second signal conditioning module includes an operational amplifier U3D; and the third signal conditioning module includes an operational amplifier U3C.
[0082] The first terminal of current transformer T1 is electrically connected to the first input terminal of rectifier bridge D2, the second terminal of current transformer T1 is electrically connected to the second input terminal of rectifier bridge D2, the first terminal of current transformer T2 is electrically connected to the first input terminal of rectifier bridge D3, the second terminal of current transformer T2 is electrically connected to the second input terminal of rectifier bridge D3, the first terminal of current transformer T3 is electrically connected to the first input terminal of rectifier bridge D4, and the second terminal of current transformer T3 is electrically connected to the second input terminal of rectifier bridge D4.
[0083] The first output terminals of rectifier bridge D2, rectifier bridge D3, and rectifier bridge D4 are electrically connected to the cathode of Zener diode ZD1 and the input terminal Vin of buck regulator chip U1, respectively. The output terminal Vout of buck regulator chip U1 is electrically connected to the power supply terminal of the main control module to output the power supply voltage VCC.
[0084] The anode of Zener diode ZD1 is electrically connected to the first terminal of sampling resistor R2, the non-inverting input terminal of operational amplifier U3B, the first terminal of sampling resistor R8, the non-inverting input terminal of operational amplifier U3D, the first terminal of sampling resistor R16, and the non-inverting input terminal of operational amplifier U3C, respectively.
[0085] The second output terminal of rectifier bridge D2 is electrically connected to the second terminal of sampling resistor R2 and the inverting input terminal of operational amplifier U3B, respectively. The output terminal of operational amplifier U3B is electrically connected to the first acquisition terminal of the main control module to output the acquisition voltage IA.
[0086] The second output terminal of rectifier bridge D3 is electrically connected to the second terminal of sampling resistor R8 and the inverting input terminal of operational amplifier U3D, respectively. The output terminal of operational amplifier U3D is electrically connected to the second acquisition terminal of the main control module to output the acquisition voltage IB.
[0087] The second output terminal of rectifier bridge D4 is electrically connected to the second terminal of sampling resistor R16 and the inverting input terminal of operational amplifier U3C, respectively. The output terminal of operational amplifier U3C is electrically connected to the third acquisition terminal of the main control module to output the acquisition voltage IC.
[0088] In this process, the currents output from the first output terminals of rectifier bridges D2, D3, and D4 simultaneously pass through Zener diode ZD1, and then through sampling resistors R2, R8, and R16 respectively, returning to the second output terminals of rectifier bridges D2, D3, and D4, forming a complete current loop. During this process, Zener diode ZD1 clamps the voltage across it to 12V, thus providing a suitable input voltage to the buck regulator chip U1.
[0089] The currents output by rectifier bridges D2, D3, and D4 form voltage drops through sampling resistors R2, R8, and R16, respectively, which enables operational amplifiers U3B, U3D, and U3C to acquire current by sampling the terminal voltages of sampling resistors R2, R8, and R16, respectively.
[0090] In this embodiment, the Zener diode ZD1 is used to discharge excess energy from the current sampling module to output a suitable voltage to the subsequent stage, while the overpower protection module composed of trigger resistor R26, PNP transistor Q3 and NPN transistor Q4 is mainly used to protect the actual discharge level of Zener diode ZD1 within its tolerable range.
[0091] Among them, targeting Figure 6 The specific circuit shown requires careful selection of the trigger resistor R26, NPN transistor Q4, and Zener diode ZD1 based on the current range generated by current transformers T1, T2, and T3. For example, if the transformer turns ratio is 1:1000 and the primary current being monitored is 10A, and long-term full-load operation is desired with overload protection exceeding 1.5 times the rated power, and the primary current of the transformer is 10A while the secondary current is 0.01A, assuming the voltage difference between the emitter and base of the PNP transistor Q3 is greater than 0.5V for conduction, then the resistance of the trigger resistor R26 is 0.5V / (10 x 1.5 / 1000) = 33Ω. The long-term operating current of the Zener diode ZD1 should have a margin, significantly greater than 0.01A. The NPN transistor Q4 should have sufficient operating voltage and current margins, with its current value at least greater than the overload current generated by the transformer.
[0092] It should be noted that, Figure 6 Components not mentioned in the above embodiments are all basic components for realizing the basic functions of the circuit, and will not be described in detail here. Specifically, they include capacitors C1, C2, C3, C4, C5, C7, and C8, as well as resistors R3, R4, R5, R6, R7, R9, R10, R11, R14, R17, R18, and R21.
[0093] Secondly, such as Figure 7 As shown, in one embodiment, the present invention provides an electronic overload protection system, which includes a relay circuit and a current detection circuit as described in any of the above embodiments.
[0094] The relay circuit is electrically connected to the main control module and is used to control the circuit containing the current sampled by the current sampling module to disconnect according to the overload drive signal output by the main control module.
[0095] The above-mentioned electronic overload protection system includes an overpower protection module. By utilizing the overpower protection module's protection function, it can conduct when the current on the current sampling module exceeds a preset current threshold, thereby diverting current to the power module, reducing the generated heat, reducing the risk of burnout, and thus improving service life.
[0096] like Figure 8 As shown, in one embodiment, the relay circuit includes a rectifier diode D1, a freewheeling diode D5, a filter capacitor C9, a resistor R23, a resistor R25, an npn transistor Q2, and a relay K1.
[0097] The anode of rectifier diode D1 is used to connect to the working voltage (such as +12V). The cathode of rectifier diode D1 is electrically connected to the first terminal of filter capacitor C9, the cathode of freewheeling diode D5, and the first terminal of the coil in relay K1. The second terminal of the coil in relay K1 is electrically connected to the collector of freewheeling diode D5 and npn transistor Q2. The base of npn transistor is electrically connected to the first terminal of resistor R23 and the first terminal of resistor R25. The second terminal of resistor R23 is used to connect to the overload drive signal Relay output by the main control module. The second terminal of resistor R25, the second terminal of capacitor C9, and the emitter of npn transistor Q2 are grounded.
[0098] When the main control module determines that the circuit containing the current to be measured is overloaded, it outputs a high-level overload drive signal Relay, and the npn transistor Q2 is turned on. The +12V working voltage is connected to the ground through the coil in relay K1 and the npn transistor Q2, forming a current loop. The relay K1 is activated, controlling the circuit containing the current to be measured to be disconnected.
[0099] It should be noted that in other embodiments, when the main control module determines that the circuit containing the current to be measured is overloaded, it outputs a low-level overload drive signal Relay. The npn transistor Q2 is cut off, and the +12V working voltage cannot pass through the coil in relay K1 and the npn transistor Q2 to reach ground, so a current loop cannot be formed. The relay K1 trips, controlling the circuit containing the current to be measured to disconnect.
[0100] It should be added that, in other embodiments, relay K1 can also work in conjunction with a corresponding contactor to control the on / off state of the circuit containing the current to be measured.
[0101] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the detailed descriptions of other embodiments above, which will not be repeated here.
[0102] The above provides a detailed description of the power supply circuit with current detection, the current detection circuit, and the electronic overload protection system provided by this utility model. Specific examples have been used to illustrate the principle and implementation of this utility model. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of this utility model. Therefore, the content of this specification should not be construed as a limitation of this utility model.
[0103] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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.
Claims
1. A power supply circuit with current detection, characterized in that, The power supply circuit in the current detection includes a current sampling module, an over-power protection module, and a power supply module. The power module and the current sampling module are electrically connected to the main control module and are used to supply power to the main control module according to the current on the current sampling module; The overpower protection module is electrically connected to the power supply module and is used to conduct when the current on the current sampling module exceeds a preset current threshold, so as to shunt the power supply module.
2. The power supply circuit with current detection according to claim 1, characterized in that, The overpower protection module includes a trigger resistor and a switching unit; The trigger resistor, the current sampling module, and the power supply module are connected in series. The trigger resistor is also electrically connected to the controlled terminal of the switching unit, and is used to output a trigger signal to the switching unit when the current on the current sampling module exceeds the preset current threshold. The first and second access terminals of the switching unit are connected in parallel with the power module and are used to conduct when the trigger signal is received, so as to shunt the power module.
3. The power supply circuit with current detection according to claim 2, characterized in that, The switching unit includes a PNP transistor; The emitter of the PNP transistor is electrically connected to the first end of the trigger resistor, the base of the PNP transistor is electrically connected to the second end of the trigger resistor and the first input terminal of the power module, and the collector of the PNP transistor is electrically connected to the second input terminal of the power module.
4. The power supply circuit with current detection according to claim 3, characterized in that, The switching unit further includes a first base resistor; The first end of the first base resistor is electrically connected to the second end of the trigger resistor and the first input terminal of the power module, respectively, and the second end of the first base resistor is electrically connected to the base of the PNP transistor.
5. The power supply circuit with current detection according to claim 2, characterized in that, The switching unit includes a PNP transistor and an NPN transistor; The emitter of the PNP transistor is electrically connected to the first terminal of the trigger resistor and the collector of the NPN transistor, respectively. The base of the PNP transistor is electrically connected to the second terminal of the trigger resistor and the first input terminal of the power module, respectively. The collector of the PNP transistor is electrically connected to the base of the NPN transistor, and the emitter of the NPN transistor is electrically connected to the second input terminal of the power module.
6. The power supply circuit with current detection according to claim 5, characterized in that, The switching unit further includes a first base resistor and / or a second base resistor; The first terminal of the first base resistor is electrically connected to the second terminal of the trigger resistor and the first input terminal of the power module, respectively; the second terminal of the first base resistor is electrically connected to the base of the PNP transistor; and / or, The first end of the second base resistor is electrically connected to the collector of the pnp transistor, and the second end of the second base resistor is electrically connected to the base of the npn transistor.
7. A current detection circuit, characterized in that, The current detection circuit includes a main control module, a signal conditioning module, and a power supply circuit with current detection as described in any one of claims 1 to 6. The signal conditioning module is electrically connected to the current sampling module and the main control module, respectively, and is used to collect the current on the current sampling module and output the corresponding sampling voltage to the main control module.
8. The current detection circuit according to claim 7, characterized in that, The current sampling module has three components, and the signal conditioning module has three components. Each of the current sampling modules is used to sample the corresponding phase current of the three-phase motor; The input terminal of the power module is electrically connected to each of the current sampling modules, and the output terminal of the power module is electrically connected to the main control module. Each of the signal conditioning modules is electrically connected to the corresponding current sampling module and the main control module.
9. The current detection circuit according to claim 7 or 8, characterized in that, The current sampling module includes a current transformer, a rectifier bridge, and a sampling resistor; the power supply module includes a Zener diode; and the signal conditioning module includes an operational amplifier. The first end of the current transformer is electrically connected to the first input end of the rectifier bridge, and the second end of the current transformer is electrically connected to the second input end of the rectifier bridge. The first output terminal of the rectifier bridge is electrically connected to the cathode of the Zener diode and the power supply terminal of the main control module, respectively. The anode of the Zener diode is electrically connected to the first terminal of the sampling resistor and the non-inverting input terminal of the operational amplifier, respectively. The second output terminal of the rectifier bridge is electrically connected to the second terminal of the sampling resistor and the inverting input terminal of the operational amplifier, respectively. The output terminal of the operational amplifier is electrically connected to the acquisition terminal of the main control module.
10. The current detection circuit according to claim 9, characterized in that, The power module also includes a step-down voltage regulator chip; The input terminal of the buck regulator chip is electrically connected to the cathode of the Zener diode, the ground terminal of the buck regulator chip is electrically connected to the anode of the Zener diode, and the output terminal of the buck regulator chip is electrically connected to the power supply terminal of the main control module.
11. An electronic overload protection system, characterized in that, The electronic overload protection system includes a relay circuit and a current detection circuit as described in any one of claims 7 to 10; The relay circuit is electrically connected to the main control module and is used to control the circuit containing the current sampled by the current sampling module to disconnect according to the overload drive signal output by the main control module.