Current-limiting protection circuit
By designing a current limit protection circuit containing an adaptive current limit trigger module, the problem that the current limit protection circuit in the prior art is difficult to adapt to different types of loads, and effective protection of the power frequency inverter and load is achieved, reducing costs and improving compatibility.
Patent Information
- Application Number
- CN202420269549.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-02-02
- Publication Date
- 2025-03-07
- Estimated Expiration
- 2034-02-02
AI Technical Summary
The current limit protection circuit of existing power frequency inverters is difficult to adapt to different types of loads, resulting in high cost and poor compatibility, and the current cannot be effectively limited in the event of an overcurrent fault, resulting in the working circuit being unable to operate normally.
A current limit protection circuit is designed, including a rectifier module, an adaptive current limit trigger module, a controller module and a driving module. By real-time detection of the low-voltage side current value of the power frequency inverter, outputting an overcurrent signal to control the clamp PWM signal, and driving the rectifier module to limit the overcurrent current and maintain normal operation.
This current limit protection circuit can adapt to all types of loads, effectively limit overcurrent current, maintain the normal operation of the working circuit, improve anti-interference ability, and be cheaper.
Smart Images
Figure CN222582284U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of transformer protection, in particular to a current limiting protection circuit. Background Art
[0002] Currently, industrial frequency inverters are widely used in household appliances in the market, so the types of loads connected to them also cover a wide range, such as switching loads, capacitive loads, inductive loads and half-wave loads, etc.; therefore, when an overcurrent fault occurs in the circuit, it is necessary to fully consider the impact of the overcurrent fault on the industrial frequency inverter and its load, and set overcurrent protection measures or current limiting measures to avoid the industrial frequency inverter and its load from burning due to overcurrent.
[0003] However, due to the wide range of load types of power frequency inverters, the overcurrent peak values reflected by different loads are different. In order to make the protection circuit adapt to all load types and power frequency inverters of different powers, the method of matching the overcurrent detection of power frequency inverters of different powers is to directly select the current detection device that can withstand it according to the inverter power; the method of matching different types of loads is to use the load type with the smallest overcurrent peak value as the overcurrent protection trigger threshold, and when the detection current exceeds the threshold, the circuit is directly shut down for protection, or the overcurrent protection circuit is designed in a targeted manner according to the actual load type connected to the power frequency inverter to timely shut down the working circuit for protection, or the current limiting protection circuit limits the overcurrent current to protect the working circuit while maintaining operation.
[0004] In summary, the matching method of different power frequency inverters will result in the cost of current detection components being too high when using high power inverters; and the method of matching different types of loads will result in: first, the overcurrent protection trigger threshold is the smallest overcurrent peak value among the load types, and it is impossible to adapt all types of loads with one protection circuit. Directly shutting down the circuit will cause some loads with large overcurrent peak values to be overprotected, work intermittently, and cannot work continuously; second, although the protection needs of different loads are met, it is necessary to frequently design the protection circuit according to the actual situation, which is time-consuming, labor-intensive, and costly, and it is impossible to match the frequency inverter with all loads. Therefore, a current limiting protection circuit is needed that can limit the overcurrent of all types of loads to protect the frequency inverter and loads while maintaining the normal operation of the working circuit, improving the anti-interference ability of the working circuit, and at a lower cost. Utility Model Content
[0005] In view of the above-mentioned defects, the purpose of the utility model is to propose a current limiting protection circuit that can adapt to the overcurrent of the industrial frequency inverter equipped with different types of loads, play a current limiting role while maintaining the normal operation of the circuit, improve the anti-interference ability of the working circuit and lower the cost.
[0006] To achieve this purpose, the utility model adopts the following technical solutions:
[0007] A current limiting protection circuit comprises a rectifier module, an adaptive current limiting trigger module, a controller module and a drive module; the input end of the rectifier module is electrically connected to the output end of the drive module, and the output end of the rectifier module is electrically connected to the low voltage side of the power frequency inverter U1;
[0008] The detection end of the self-adaptive current limiting trigger module is electrically connected to multiple lead wires of the positive or negative pole on the low voltage side of the power frequency inverter U1, or the detection end of the self-adaptive current limiting trigger module is electrically connected to the positive or negative pole on the low voltage side of the power frequency inverter U1; the output end of the self-adaptive current limiting trigger module is electrically connected to the input end of the controller module, and the output end of the controller module is electrically connected to the input end of the drive module;
[0009] The adaptive current limiting trigger module is used to detect the low-voltage side current value I1 of the power frequency inverter U1 in real time to determine whether it is greater than the internally adjustable overcurrent threshold I2; when the low-voltage side current value I1 is greater than the overcurrent threshold I2, the adaptive current limiting trigger module outputs an overcurrent signal; when the low-voltage side current value I1 is less than the overcurrent threshold I2, the adaptive current limiting trigger module outputs a normal signal;
[0010] The controller module is used to output a clamping PWM signal when receiving the overcurrent signal; and not to act when receiving the normal signal;
[0011] The driving module is used to drive the rectifier module according to the clamped PWM signal when receiving the clamped PWM signal; otherwise, the driving module is used to drive the rectifier module according to the original PWM signal.
[0012] Furthermore, the adaptive current limiting trigger module includes a current detection component CT1 and an overcurrent threshold trigger unit; the detection end of the current detection component CT1 is used as the detection end of the adaptive current limiting trigger module, and the output end of the overcurrent threshold trigger unit is used as the output end of the adaptive current limiting trigger module;
[0013] The output end of the current detection element CT1 is electrically connected to the input end of the overcurrent threshold trigger unit;
[0014] The current detection element CT1 is used to detect the low-voltage side current value I1 in real time;
[0015] The overcurrent threshold trigger unit is used to receive the low-voltage side current value I1 to determine whether it is greater than the overcurrent threshold I2; when the low-voltage side current value I1 is greater than the overcurrent threshold I2, the overcurrent threshold trigger unit outputs the overcurrent signal; when the low-voltage side current value I1 is less than the overcurrent threshold I2, the overcurrent threshold trigger unit outputs the normal signal.
[0016] Furthermore, the overcurrent threshold I2 is smaller than the maximum detection current I3 of the current detection component CT1.
[0017] Furthermore, the number N1 of the lead wires electrically connected to the detection end of the current detection element is:
[0018] N1≤(I3*N2) / I4 and only the integer part of the result is taken;
[0019] Wherein: I3 is the maximum detection current of the current detection component CT1, I4 is the current value of the power frequency inverter U1 that needs overcurrent protection, and N2 is the total number of the lead wires.
[0020] Further, the overcurrent threshold trigger unit includes an overcurrent threshold adjustment circuit, a resistor R28, a resistor R29, a resistor R31, a capacitor C14, a capacitor C29, a capacitor C46, a capacitor C49, a comparator U10A and a comparator U10B; one end of the resistor R29 is used as an input end of the overcurrent threshold trigger unit, and one end of the resistor R31 is used as an output end of the overcurrent threshold trigger unit;
[0021] The other end of the resistor R29, one end of the capacitor C29, and the positive input end of the comparator U10B are all electrically connected to the negative input end of the comparator U10A, and the other end of the capacitor C29 is grounded. The first adjustment end of the overcurrent threshold adjustment circuit and one end of the capacitor C14 are all electrically connected to the positive input end of the comparator U10A, and the other end of the capacitor C14 is grounded. The second adjustment end of the overcurrent threshold adjustment circuit and one end of the capacitor C49 are all electrically connected to the negative input end of the comparator U10B, and the other end of the capacitor C49 is grounded. The output end of the comparator U10A, the output end of the comparator U10B, and one end of the resistor R28 are all electrically connected to the other end of the resistor R31, and the other end of the resistor R28 is connected to the power supply voltage. One end of the capacitor C46 is electrically connected to one end of the resistor R31, and the other end of the capacitor C46 is grounded.
[0022] Further, the overcurrent threshold adjustment circuit includes a resistor R27, a resistor R30 and a resistor R34; one end of the resistor R30 is used as a first adjustment end of the overcurrent threshold adjustment circuit, and the other end of the resistor R30 is used as a second adjustment end of the overcurrent threshold adjustment circuit;
[0023] One end of the resistor R27 is connected to the adjustment voltage, the other end of the resistor R27 is electrically connected to one end of the resistor R30, the other end of the resistor R30 is electrically connected to one end of the resistor R34, and the other end of the resistor R34 is grounded.
[0024] Furthermore, the current detection component CT1 is a current sensor.
[0025] Furthermore, the rectifier module includes a MOS tube Q1, a MOS tube Q2, a MOS tube Q3 and a MOS tube Q4; the drain of the MOS tube Q1 and the source of the MOS tube Q3 are both used as the input end of the rectifier module, and the source of the MOS tube Q1 and the source of the MOS tube Q2 are both used as the output end of the rectifier module;
[0026] The drain of the MOS transistor Q1 is electrically connected to the drain of the MOS transistor Q2, the source of the MOS transistor Q2 is electrically connected to the drain of the MOS transistor Q4, the source of the MOS transistor Q4 is electrically connected to the source of the MOS transistor Q3, and the drain of the MOS transistor Q3 is electrically connected to the source of the MOS transistor Q1.
[0027] The technical solution provided by the utility model may include the following beneficial effects: the self-adaptive current limiting trigger module can detect whether there is an overcurrent fault in the power frequency inverter and its load by being electrically connected to the low-voltage side of the power frequency inverter; in order to enable the self-adaptive current limiting trigger module 2 to adapt to the current when the power frequency inverter carries different loads; when the detected current exceeds the bearing capacity of the self-adaptive current limiting trigger module, the current value requiring overcurrent protection can be evenly divided by leading out multiple lead wires from the low-voltage side of the power frequency inverter according to the current value of the load carried by the power frequency inverter that requires overcurrent protection, and then the self-adaptive current limiting trigger module can be electrically connected to the corresponding number of lead wires according to its own current bearing capacity to adapt to the load it carries, so that the self-adaptive current limiting trigger module does not need to replace the detection component according to the load it carries so that it can fully withstand the overcurrent The current value of the action protection can monitor the current conditions of the power frequency inverter and its load in real time, reducing the cost and improving the compatibility of the current limiting circuit; thus, the self-adaptive current limiting trigger module can enable the controller module to output a clamped PWM signal when the power frequency inverter and its load are overcurrent, so that the drive module is only controlled by the clamped PWM signal at this time, and only drives the rectifier module and its subsequent circuit to work normally according to the clamped PWM signal, without being disturbed by the original PWM signal disturbed by the overcurrent fault, so as to achieve the purpose of limiting the overcurrent and maintaining normal operation; and then the current limiting protection circuit can adapt to the overcurrent protection of all types of loads (that is, limiting the overcurrent of the power frequency inverter U1 in different power ranges) while maintaining the normal operation of the working circuit of the power frequency inverter and load, thereby improving the anti-interference ability of the working circuit and lowering the cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 It is a principle diagram of a current limiting protection circuit in one embodiment of the utility model.
[0029] Figure 2 Yes Figure 1 The circuit diagram of the adaptive current limiting trigger module is shown.
[0030] Among them: power frequency inverter U1, rectifier module 1, adaptive current limiting trigger module 2, controller module 3, drive module 4, current detection component CT1, overcurrent threshold trigger unit 21, overcurrent threshold adjustment circuit 211, resistor R28, resistor R29, resistor R31, capacitor C14, capacitor C29, capacitor C46, capacitor C49, comparator U10A, comparator U10B, resistor R27, resistor R30, resistor R34, MOS tube Q1, MOS tube Q2, MOS tube Q3, MOS tube Q4. DETAILED DESCRIPTION
[0031] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.
[0032] In the description of the embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.
[0033] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.
[0034] Combine the following Figure 1 to Figure 2 , describing a current limiting protection circuit of an embodiment of the utility model.
[0035] A current limiting protection circuit includes a rectifier module 1, an adaptive current limiting trigger module 2, a controller module 3 and a drive module 4; the input end of the rectifier module 1 is electrically connected to the output end of the drive module 4, and the output end of the rectifier module 1 is electrically connected to the low-voltage side of the power frequency inverter U1;
[0036] The detection end of the adaptive current limiting trigger module 2 is electrically connected to the multiple lead wires of the positive or negative pole on the low voltage side of the power frequency inverter U1, or the detection end of the adaptive current limiting trigger module 2 is electrically connected to the positive or negative pole on the low voltage side of the power frequency inverter U1; the output end of the adaptive current limiting trigger module 2 is electrically connected to the input end of the controller module 3, and the output end of the controller module 3 is electrically connected to the input end of the drive module 4;
[0037] The adaptive current limiting trigger module 2 is used to detect the low-voltage side current value I1 of the power frequency inverter U1 in real time to determine whether it is greater than the internal adjustable overcurrent threshold I2; when the low-voltage side current value I1 is greater than the overcurrent threshold I2, the adaptive current limiting trigger module 2 outputs an overcurrent signal; when the low-voltage side current value I1 is less than the overcurrent threshold I2, the adaptive current limiting trigger module 2 outputs a normal signal;
[0038] The controller module 3 is used to output a clamping PWM signal when receiving an overcurrent signal; and does not act when receiving a normal signal;
[0039] The driving module 4 is used to drive the rectifier module 1 according to the clamped PWM signal when receiving the clamped PWM signal; otherwise, the driving module 4 is used to drive the rectifier module 1 according to the original PWM signal.
[0040] The utility model proposes a preferred embodiment of a current limiting protection circuit, such as Figure 1As shown, the drive module 4, the rectifier module 1 and the industrial frequency inverter U1 constitute a circuit (working circuit) for normally driving the load; the adaptive current limiting trigger module 2 and the controller module 3 (such as MCU) constitute a current detection and overcurrent fault current limiting circuit. Among them, because when the industrial frequency inverter U1 carries different loads, the current it starts for different loads is different, so the self-adaptive current limiting trigger module 2 can detect whether there is an overcurrent fault in the industrial frequency inverter U1 and its load by being electrically connected to the low-voltage side of the industrial frequency inverter U1; in order to make the self-adaptive current limiting trigger module 2 adaptable to detect the current when the industrial frequency inverter U1 carries different loads; when the detected current exceeds the bearing capacity of the self-adaptive current limiting trigger module 2, multiple lead wires can be drawn from the low-voltage side of the industrial frequency inverter U1 according to the current value of the load carried by the industrial frequency inverter U1 that requires overcurrent protection to evenly divide the current value that requires overcurrent protection, and then the self-adaptive current limiting trigger module 2 can be electrically connected to the corresponding number of lead wires according to its own current bearing capacity to adapt to the load it carries, so that the self-adaptive current limiting trigger module 2 does not need to replace the detection component according to the load it carries. It can fully withstand the current value that requires overcurrent protection, and can monitor the current conditions of the power frequency inverter U1 and its load in real time, reducing costs and improving the compatibility of the current limiting circuit; thus, the self-adaptive current limiting trigger module 2 can enable the controller module 3 to output a clamped PWM signal when the power frequency inverter U1 and its load are overcurrent, so that the drive module 4 is only controlled by the clamped PWM signal at this time, and only drives the rectifier module 1 and its subsequent circuits to work normally according to the clamped PWM signal, without being disturbed by the original PWM signal disturbed by the overcurrent fault, so as to achieve the purpose of limiting the overcurrent and maintaining normal operation; and then the current limiting protection circuit can adapt to the overcurrent protection of all types of loads (that is, limiting the overcurrent of the power frequency inverter U1 in different power segments) while maintaining the normal operation of the working circuit while the power frequency inverter and load, thereby improving the anti-interference ability of the working circuit and lowering the cost.
[0041] It should be noted that when the current value of the overcurrent protection required for the power frequency inverter U1 does not exceed the current bearing capacity of the self-adaptive current limiting trigger module 2, the detection end of the self-adaptive current limiting trigger module 2 can be directly electrically connected to the positive or negative pole of the low voltage side of the power frequency inverter U1; only when the current value of the overcurrent protection required for the power frequency inverter U1 exceeds the current bearing capacity of the self-adaptive current limiting trigger module 2, the detection end of the self-adaptive current limiting trigger module 2 needs to be electrically connected to the multiple lead wires of the positive or negative pole of the low voltage side of the power frequency inverter U1. It should also be noted that the adjustable overcurrent threshold I2 set in the self-adaptive current limiting trigger module 2 can be adjusted and set according to the load type carried by the power frequency inverter U1, corresponding to the current value of the overcurrent protection required for the power frequency inverter U1 and its load, so that the current limiting circuit matches the power frequency inverter U1 and its load, and is suitable for more application scenarios.
[0042] Furthermore, the adaptive current limiting trigger module 2 includes a current detection component CT1 and an overcurrent threshold trigger unit 21; the detection end of the current detection component CT1 is used as the detection end of the adaptive current limiting trigger module 2, and the output end of the overcurrent threshold trigger unit 21 is used as the output end of the adaptive current limiting trigger module 2;
[0043] The output end of the current detection element CT1 is electrically connected to the input end of the overcurrent threshold trigger unit 21;
[0044] The current detection component CT1 is used to detect the low-voltage side current value I1 in real time;
[0045] The overcurrent threshold trigger unit 21 is used to receive the low-voltage side current value I1 to determine whether it is greater than the overcurrent threshold I2; when the low-voltage side current value I1 is greater than the overcurrent threshold I2, the overcurrent threshold trigger unit 21 outputs an overcurrent signal; when the low-voltage side current value I1 is less than the overcurrent threshold I2, the overcurrent threshold trigger unit 21 outputs a normal signal.
[0046] In this embodiment, the current detection function of the self-adaptive current limiting trigger module 2 is electrically connected by the current detection device CT1 and multiple lead wires on the low-voltage side of the power frequency inverter U1 to adapt to different loads of the power frequency inverter U1 to perform real-time low-voltage side current value I1 detection; under the premise that the current detection device CT1 completes the adaptation, the overcurrent threshold I2 trigger unit 21 only needs to play a judgment role, and only when the low-voltage side current value I1 is greater than the overcurrent threshold I2, the output overcurrent signal is triggered to trigger the controller module 3 to output a clamping PWM signal for clamping and limiting the overcurrent of the working circuit and maintaining normal working state.
[0047] Furthermore, the overcurrent threshold value I2 is smaller than the maximum detection current I3 of the current detection element CT1 .
[0048] In this embodiment, because the current detection component CT1 completes the adaptation with the power frequency inverter U1 of different powers through the number of electrical connection lead wires according to its own current bearing capacity, the maximum detection current I3 of the current detection component CT1 is the maximum overcurrent threshold, and the overcurrent threshold I2 should always be less than the maximum detection current I3 of the current detection component CT1. It should be noted that the overcurrent threshold I2 can be freely taken within the range of less than the maximum detection current I3 of the current detection component CT1 to match the current value of the overcurrent action protection required by the power frequency inverter U1 of different powers, so as to meet the overcurrent action requirements of different types of loads.
[0049] Furthermore, the number N1 of the lead wires electrically connected to the detection end of the current detection element 21 is:
[0050] N1≤(I3*N2) / I4 and only the integer part of the result is taken;
[0051] Among them: I3 is the maximum detection current of the current detection component CT1, I4 is the current value of the power frequency inverter U1 that needs overcurrent protection, and N2 is the total number of lead wires.
[0052] In this embodiment, I3 is the maximum detection current of the current detection device CT1, that is, the detection range, and also the maximum current carrying capacity; I4 is the current value that the power frequency inverter U1 needs to be protected by overcurrent action, which means that when the current value exceeds this value, overcurrent protection is required to clamp and limit the current and maintain normal operation; N2 is the total number of lead wires, and the number of lead wires can be selected according to the size of I4; from the above relationship, it can be deduced that the number N1 of the lead wires electrically connected to the detection end of the current detection device 21 can be obtained by the formula N1≤(I3*N2) / I4, and when N1 cannot be divided evenly, in order to avoid the total current of the electrically connected lead wires exceeding the carrying capacity of the current detection device CT1 due to carry, only the integer part of the result is taken. Specific examples are: I3=200A, I4=600A, N2=20, then N1=6; the current value of a single lead wire = I4 / N2=30A, and the total current after the current detection device CT1 is electrically connected to 6 lead wires = 6*30A=180A, which is less than the maximum detection current (maximum withstand current) I3 of the current detection device CT1; the requirements are met.
[0053] Further, the overcurrent threshold trigger unit 21 includes an overcurrent threshold adjustment circuit 211, a resistor R28, a resistor R29, a resistor R31, a capacitor C14, a capacitor C29, a capacitor C46, a capacitor C49, a comparator U10A and a comparator U10B; one end of the resistor R29 is used as an input end of the overcurrent threshold trigger unit 21, and one end of the resistor R31 is used as an output end of the overcurrent threshold trigger unit 21;
[0054] The other end of the resistor R29, one end of the capacitor C29, and the positive input end of the comparator U10B are all electrically connected to the negative input end of the comparator U10A, and the other end of the capacitor C29 is grounded. The first adjustment end of the overcurrent threshold adjustment circuit 211 and one end of the capacitor C14 are all electrically connected to the positive input end of the comparator U10A, and the other end of the capacitor C14 is grounded. The second adjustment end of the overcurrent threshold adjustment circuit 211 and one end of the capacitor C49 are all electrically connected to the negative input end of the comparator U10B, and the other end of the capacitor C49 is grounded. The output end of the comparator U10A, the output end of the comparator U10B, and one end of the resistor R28 are all electrically connected to the other end of the resistor R31, and the other end of the resistor R28 is connected to the power supply voltage. One end of the capacitor C46 is electrically connected to one end of the resistor R31, and the other end of the capacitor C46 is grounded.
[0055] In this embodiment, because the low-voltage side current of the industrial frequency inverter U1 is an analog current signal with positive and negative values, the window comparison circuit composed of resistor R28, resistor R29, resistor R31, capacitor C14, capacitor C29, capacitor C46, capacitor C49, comparator U10A and comparator U10B can identify the analog current signal with positive and negative values and compare it with the reference value set by the overcurrent threshold adjustment circuit 211 to obtain whether the overcurrent threshold trigger unit 21 outputs an overcurrent signal or a normal signal (i.e., high or low level). The window comparison circuit has a limiting function, which can limit the maximum amplitude of the input signal to prevent it from exceeding the maximum detection range. It is very suitable for overcurrent detection and judgment, and plays a role in ensuring that the subsequent circuit only limits the current but does not shut down.
[0056] It should be noted that, in the case where different types of loads result in different powers of the power frequency inverter U1 and thus different overcurrent thresholds, the reference value of the overcurrent threshold adjustment circuit 211 can be adjusted to match the different load conditions.
[0057] Furthermore, the overcurrent threshold adjustment circuit 211 includes a resistor R27, a resistor R30 and a resistor R34; one end of the resistor R30 is used as a first adjustment end of the overcurrent threshold adjustment circuit 211, and the other end of the resistor R30 is used as a second adjustment end of the overcurrent threshold adjustment circuit 211;
[0058] One end of the resistor R27 is connected to the adjustment voltage, the other end of the resistor R27 is electrically connected to one end of the resistor R30, the other end of the resistor R30 is electrically connected to one end of the resistor R34, and the other end of the resistor R34 is grounded.
[0059] In this embodiment, the reference value provided by the overcurrent threshold adjustment circuit 211 to the window comparison circuit is implemented by a voltage divider circuit, which can be achieved by adjusting the resistance values of the resistors R27, R30 and R34 or the voltage value of the voltage.
[0060] Furthermore, the current detection component CT1 is a current sensor.
[0061] In this embodiment, the current sensor can be used to measure AC and DC currents, as well as high-precision small current measurements, by using electromagnetic induction and the Hall effect. It can be used in various current detection scenarios and is very suitable for current detection when the industrial frequency inverter U1 is equipped with different types of loads.
[0062] Furthermore, the rectifier module 1 includes a MOS transistor Q1, a MOS transistor Q2, a MOS transistor Q3 and a MOS transistor Q4; the drain of the MOS transistor Q1 and the source of the MOS transistor Q3 are both used as the input end of the rectifier module 1, and the source of the MOS transistor Q1 and the source of the MOS transistor Q2 are both used as the output end of the rectifier module 1;
[0063] The drain of MOS transistor Q1 is electrically connected to the drain of MOS transistor Q2, the source of MOS transistor Q2 is electrically connected to the drain of MOS transistor Q4, the source of MOS transistor Q4 is electrically connected to the source of MOS transistor Q3, and the drain of MOS transistor Q3 is electrically connected to the source of MOS transistor Q1.
[0064] In this embodiment, because the rectifier module composed of diodes has the disadvantages of too high conduction voltage drop and large rectification loss; while the rectifier module composed of MOS tubes has relatively low on-resistance and high efficiency, which can reduce rectification loss and save energy. At the same time, because MOS tubes are voltage-type devices, they have high stability and strong anti-interference ability, so the current detection component CT1 detects the current between the MOS tube rectifier module and the inverter U1 more accurately and sensitively.
[0065] Other structures and operations of a current limiting protection circuit according to an embodiment of the utility model are known to ordinary technicians in the field and will not be described in detail here.
[0066] In the description of this specification, the description with reference to the terms "embodiment", "example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.
[0067] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.
Claims
1. A current limiting protection circuit, characterized in that: It includes a rectifier module, an adaptive current limiting trigger module, a controller module and a drive module; the input end of the rectifier module is electrically connected to the output end of the drive module, and the output end of the rectifier module is electrically connected to the low-voltage side of the power frequency inverter U1; The detection end of the self-adaptive current limiting trigger module is electrically connected to multiple lead wires of the positive or negative pole on the low voltage side of the power frequency inverter U1, or the detection end of the self-adaptive current limiting trigger module is electrically connected to the positive or negative pole on the low voltage side of the power frequency inverter U1; the output end of the self-adaptive current limiting trigger module is electrically connected to the input end of the controller module, and the output end of the controller module is electrically connected to the input end of the drive module; The adaptive current limiting trigger module is used to detect the low-voltage side current value I1 of the power frequency inverter U1 in real time to determine whether it is greater than the internally adjustable overcurrent threshold I2; when the low-voltage side current value I1 is greater than the overcurrent threshold I2, the adaptive current limiting trigger module outputs an overcurrent signal; when the low-voltage side current value I1 is less than the overcurrent threshold I2, the adaptive current limiting trigger module outputs a normal signal; The controller module is used to output a clamping PWM signal when receiving the overcurrent signal; and not to act when receiving the normal signal; The driving module is used to drive the rectifier module according to the clamped PWM signal when receiving the clamped PWM signal; otherwise, the driving module is used to drive the rectifier module according to the original PWM signal.
2. A current limiting protection circuit according to claim 1, characterized in that: The adaptive current limiting trigger module includes a current detection component CT1 and an overcurrent threshold trigger unit; the detection end of the current detection component CT1 is used as the detection end of the adaptive current limiting trigger module, and the output end of the overcurrent threshold trigger unit is used as the output end of the adaptive current limiting trigger module; The output end of the current detection element CT1 is electrically connected to the input end of the overcurrent threshold trigger unit; The current detection element CT1 is used to detect the low-voltage side current value I1 in real time; The overcurrent threshold trigger unit is used to receive the low-voltage side current value I1 to determine whether it is greater than the overcurrent threshold I2; when the low-voltage side current value I1 is greater than the overcurrent threshold I2, the overcurrent threshold trigger unit outputs the overcurrent signal; when the low-voltage side current value I1 is less than the overcurrent threshold I2, the overcurrent threshold trigger unit outputs the normal signal.
3. A current limiting protection circuit according to claim 2, characterized in that: The overcurrent threshold I2 is smaller than the maximum detection current I3 of the current detection element CT1.
4. A current limiting protection circuit according to claim 2, characterized in that: The number N1 of the lead wires electrically connected to the detection end of the current detection member is: N1≤(I3*N2) / I4 and only the integer part of the result is taken; Wherein: I3 is the maximum detection current of the current detection component CT1, I4 is the current value of the power frequency inverter U1 that needs overcurrent protection, and N2 is the total number of the lead wires.
5. A current limiting protection circuit according to claim 2, characterized in that: The overcurrent threshold trigger unit includes an overcurrent threshold adjustment circuit, a resistor R28, a resistor R29, a resistor R31, a capacitor C14, a capacitor C29, a capacitor C46, a capacitor C49, a comparator U10A and a comparator U10B; one end of the resistor R29 is used as an input end of the overcurrent threshold trigger unit, and one end of the resistor R31 is used as an output end of the overcurrent threshold trigger unit; The other end of the resistor R29, one end of the capacitor C29, and the positive input end of the comparator U10B are all electrically connected to the negative input end of the comparator U10A, and the other end of the capacitor C29 is grounded. The first adjustment end of the overcurrent threshold adjustment circuit and one end of the capacitor C14 are all electrically connected to the positive input end of the comparator U10A, and the other end of the capacitor C14 is grounded. The second adjustment end of the overcurrent threshold adjustment circuit and one end of the capacitor C49 are all electrically connected to the negative input end of the comparator U10B, and the other end of the capacitor C49 is grounded. The output end of the comparator U10A, the output end of the comparator U10B, and one end of the resistor R28 are all electrically connected to the other end of the resistor R31, and the other end of the resistor R28 is connected to the power supply voltage. One end of the capacitor C46 is electrically connected to one end of the resistor R31, and the other end of the capacitor C46 is grounded.
6. A current limiting protection circuit according to claim 5, characterized in that: The overcurrent threshold adjustment circuit includes a resistor R27, a resistor R30 and a resistor R34; one end of the resistor R30 is used as a first adjustment end of the overcurrent threshold adjustment circuit, and the other end of the resistor R30 is used as a second adjustment end of the overcurrent threshold adjustment circuit; One end of the resistor R27 is connected to the adjustment voltage, the other end of the resistor R27 is electrically connected to one end of the resistor R30, the other end of the resistor R30 is electrically connected to one end of the resistor R34, and the other end of the resistor R34 is grounded.
7. A current limiting protection circuit according to claim 2, characterized in that: The current detection element CT1 is a current sensor.
8. A current limiting protection circuit according to claim 1, characterized in that: The rectifier module includes a MOS transistor Q1, a MOS transistor Q2, a MOS transistor Q3 and a MOS transistor Q4; the drain of the MOS transistor Q1 and the source of the MOS transistor Q3 are both used as the input end of the rectifier module, and the source of the MOS transistor Q1 and the source of the MOS transistor Q2 are both used as the output end of the rectifier module; The drain of the MOS transistor Q1 is electrically connected to the drain of the MOS transistor Q2, the source of the MOS transistor Q2 is electrically connected to the drain of the MOS transistor Q4, the source of the MOS transistor Q4 is electrically connected to the source of the MOS transistor Q3, and the drain of the MOS transistor Q3 is electrically connected to the source of the MOS transistor Q1.