CT electricity-taking power supply circuit

Abstract

The utility model discloses a current transformer (CT) electricity-taking power supply circuit, and relates to the technical field of switching power supplies. Comprising a CT coil interface, an input protection circuit, a post-stage protection circuit, a rectification circuit, a switching power supply circuit, a charging management circuit, a first current detection circuit, a first voltage detection circuit, a second voltage detection circuit and a second current detection circuit. And the input protection circuit is connected to the CT coil interface and is used for protecting a post-stage circuit from being damaged. And the rectifying circuit is connected between the post-stage protection circuit and the switching power supply circuit and is used for converting alternating current into direct current. The output end of the power supply circuit is electrically connected with the charging management circuit. And the first current detection circuit and the voltage detection circuit are isolated detection circuits, are respectively arranged between the post-stage protection circuit and the rectification circuit and between the rectification circuit and the switching power supply circuit, and are used for realizing real-time detection of current and voltage.

Description

Technical Field

[0001] The utility model relates to the technical field of switch power supply, and more specifically, to a CT power supply circuit. Background Art

[0002] With the continuous increase in electricity demand, the power system is gradually developing towards large capacity, high voltage and intelligence. At the same time, all walks of life have higher and higher requirements for power supply stability, which has led to stricter requirements for the reliability of line operation and the rapidity of line fault elimination. In modern electrical systems, the detection of current and voltage is the basis of system health monitoring and fault diagnosis, and plays a vital role. In particular, in the switching power supply system, the accurate detection of current and voltage can not only effectively ensure the stable operation of the power supply system, but also protect the safety of the power supply system and the powered equipment to a certain extent. Therefore, designing a suitable current and voltage detection circuit is very critical for the switching power supply system.

[0003] However, the current detection technology widely used in switching power supply systems currently mainly uses the current loop as a sensor to measure the current by detecting the induced current. However, this method has some significant limitations. First, the input and output current ratio of the traditional current loop is fixed and the volume is large, which undoubtedly brings certain troubles to the system design. Secondly, the current detection accuracy of the current loop is not high, which means that large errors may occur during the current detection process and cannot meet the actual needs of the system. In addition, for isolated switching power supplies, in order to perform current detection on the isolated side, it is usually necessary to use an isolated current detection circuit, and the design and implementation of this circuit is often relatively complex.

[0004] Similarly, voltage detection is also an indispensable part of the switching power supply system. Conventional voltage detection is non-isolated. The voltage is reduced to a level range suitable for the microprocessor (MCU) to receive through a voltage divider network, and then connected to the analog / digital converter (ADC) input port of the MCU. The voltage level is read through the ADC of the MCU to calculate the detected voltage. However, this method has certain limitations. For example, for some special systems, such as the voltage induced by the current transformer (CT) coil, it will change with the power of the power line, and the range of change is very large, from tens of volts to hundreds of volts, so voltage detection is required. At this time, it is obviously inappropriate to use non-isolated voltage detection. Utility Model Content

[0005] In order to overcome the deficiencies of the prior art, the utility model provides a CT power supply circuit, which adopts an isolated current and voltage detection circuit, reduces measurement errors, improves the operating efficiency of the circuit, and greatly reduces the size and weight of the equipment without reducing the performance of the equipment.

[0006] The technical solution adopted by the utility model to solve the technical problem is: a CT power supply circuit, the improvement of which is that it includes a CT coil interface, an input protection circuit, a post-stage protection circuit, a rectifier circuit, a switching power supply circuit, a charging management circuit, a first current detection circuit, a first voltage detection circuit, a second voltage detection circuit and a second current detection circuit;

[0007] The output end of the CT coil interface is electrically connected to the input end of the input protection circuit to protect the subsequent circuit from damage. The output end of the input protection circuit is electrically connected to the input end of the subsequent protection circuit. The rectifier circuit is electrically connected between the output end of the subsequent protection circuit and the input end of the switching power supply circuit. The output end of the switching power supply circuit is electrically connected to the charging management circuit. The first current detection circuit is arranged between the output end of the subsequent protection circuit and the input end of the rectifier circuit. The first voltage detection circuit is arranged between the output end of the rectifier circuit and the input end of the switching power supply circuit. The second voltage detection circuit is electrically connected to the output end of the switching power supply. The second current detection circuit is arranged between the output end of the switching power supply circuit and the charging management input end. The first current detection circuit and the first voltage detection circuit are isolated detection circuits, and the second current detection circuit and the second voltage detection circuit are non-isolated detection circuits.

[0008] In the above structure, the first current detection circuit includes a chip U4, a resistor R33 and a resistor R35. The chip U4 is an isolated ADC, whose model is AMC3306. One end of the resistor R33 is connected to the post-stage protection circuit, and the other end is connected to the IN+ pin of the chip U4. One end of the resistor R35 is connected to the post-stage protection circuit, and the other end is connected to the IN- pin of the chip U4.

[0009] In the above structure, the first voltage detection circuit includes a chip U3, a voltage divider circuit, a resistor R31 and a resistor R32. The chip U3 is an isolated ADC, whose model is AMC3336. One end of the resistor R31 is connected to the voltage divider circuit, and the other end is connected to the IN+ pin of the chip U3. One end of the resistor R32 is connected to the voltage divider circuit, and the other end is connected to the IN- pin of the chip U3.

[0010] In the above structure, the voltage divider circuit includes a resistor R29, a resistor R121 and a resistor R34, which are connected in series, a common end of the resistor R29 and the resistor R12 is connected to the resistor R31, and a common end of the resistor R121 and the resistor R34 is connected to the resistor R32.

[0011] In the above structure, the charging management circuit includes a resistor R42, a resistor R52, a chip U5, a light-emitting diode D15, a resistor R43, a field effect transistor Q2, a diode D13, an inductor L5, a resistor R47, a resistor R48, a resistor R49, a resistor R54, a field effect transistor Q3, a resistor R51, a resistor R53, a resistor R50 and a capacitor C42;

[0012] The resistor R42 and the resistor R52 are connected in series, one end of which is connected to the power supply end, and the other end is grounded. The common end of the resistor R42 and the resistor R52 is connected to the MPPT pin of the chip U5. The cathode of the light-emitting diode D15 is connected to the CHRG pin of the chip U5, and the anode is connected to one end of the resistor R43. The other end of the resistor R43 is short-circuited to the power supply. The gate of the field effect tube Q2 is connected to the DRV level of the chip U5, the source is connected to the power supply end, the drain is connected to the anode of the diode D13, the cathode of the diode D13 is connected to one end of the inductor L5, and the other end of the inductor L5 is connected through the resistor R47, connected to the CSP pin of chip U5, the resistor R49 and the resistor R54 are connected in series, one end of which is connected to the inductor L5, and the other end is grounded, the common end of the resistor R49 and the resistor R54 is connected to the FB pin of chip U5, the drain of the field effect transistor Q3 is connected to the COM pin of chip U5, the source is connected to the GND pin of chip U5, and the gate is connected to the resistor R51, one end of the resistor R53 is connected to the resistor R51, and the other end is grounded, the resistor R50 and the capacitor C42 are connected in series, one end is connected to the COM pin of chip U5, and the other end is connected to the GND pin of chip U5.

[0013] In the above structure, the charging management circuit also includes a resistor R37 and a resistor R48, one end of the resistor R37 is connected to the inductor L5, and the other end is connected to the BAT pin of the chip U5, the common end of the resistor R37 and the inductor L5 is connected to the CSP pin of the chip U5, and one end of the resistor R48 is connected to the BAT pin of the chip U5, and the other end is connected to the resistor R37.

[0014] In the above structure, the input protection circuit includes a varistor RV1, a gas discharge tube GDT2, a differential mode inductor L1, a voltage clamping circuit and an H-bridge circuit;

[0015] The two ends of the varistor RV1, the gas discharge tube GDT2, the voltage clamping circuit and the H-bridge circuit are connected in parallel and are respectively connected to the two ends of the CT coil interface, and the two ends of the differential mode inductor L1 are respectively connected to the gas discharge tube GDT2 and the voltage clamping circuit.

[0016] In the above structure, the voltage clamping circuit includes a capacitor CY1, a resistor R10, a resistor R11, a diode D3 and a thyristor TR1;

[0017] The capacitor CY1 and the resistor R10 are connected in series and are respectively connected to the two ends of the CT coil interface, one end of the resistor R11 is connected to the CT coil interface, and the other end is connected to the cathode of the diode D3, the anode of the diode D3 is connected to the G interface of the thyristor TR1, and the other two interfaces of the transistor are respectively connected to the two ends of the CT coil interface, and the common end of the resistor R11 and the capacitor CY1 is connected to the common end of the resistor R11 and the diode D3.

[0018] In the above structure, the post-stage protection circuit includes a common-mode inductor L3, a gas discharge tube GDT1, a differential-mode inductor L4, a bidirectional transient suppression diode D1 and a detection resistor R1; the gas discharge tube GDT1 and the bidirectional transient suppression diode D1 are connected in parallel and then in series with the common-mode inductor L3, the two ends of the differential-mode inductor L4 are respectively connected to the gas discharge tube GDT1 and the bidirectional transient suppression diode D1, one end of the detection resistor R1 is connected to the bidirectional transient suppression diode D1, and the other end is connected to the rectifier circuit.

[0019] In the above structure, the rectifier circuit is a bridge rectifier circuit, which is composed of 4 diodes and realizes rectification through the unidirectional conductivity of the diodes.

[0020] The beneficial effects of the utility model are: an isolated current and voltage detection circuit is adopted, the measurement error is reduced, the operation efficiency of the circuit is improved, and the volume and weight of the device are greatly reduced without reducing the performance of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a block diagram of a CT power supply circuit of the utility model;

[0022] Figure 2 This is a circuit schematic diagram of an input protection circuit of a CT power supply circuit of the utility model;

[0023] Figure 3 This is a circuit schematic diagram of a rear-stage protection circuit of a CT power supply circuit of the utility model;

[0024] Figure 4 It is a circuit principle diagram of a rectifier circuit of a CT power supply circuit of the utility model;

[0025] Figure 5 It is a circuit schematic diagram of a first current detection circuit of a CT power supply circuit of the utility model;

[0026] Figure 6 It is a circuit schematic diagram of a first voltage detection circuit of a CT power supply circuit of the utility model;

[0027] Figure 7 The utility model is a circuit schematic diagram of a charging management circuit of a CT power supply circuit. DETAILED DESCRIPTION

[0028] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0029] The following will clearly and completely describe the concept, specific structure and technical effects of the utility model in combination with the embodiments and drawings, so as to fully understand the purpose, characteristics and effects of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, other embodiments obtained by technicians in this field without creative work are all within the scope of protection of the utility model. In addition, all the connection / connection relationships involved in the patent do not refer to the direct connection of components, but refer to the formation of a better connection structure by adding or reducing connection accessories according to the specific implementation situation. The various technical features in the creation of the utility model can be combined interchangeably without conflicting with each other.

[0030] Reference Figures 1 to 7 As shown, the utility model discloses a CT power supply circuit, specifically, including a CT coil interface 10, an input protection circuit 20, a post-stage protection circuit 30, a rectifier circuit 40, a switching power supply circuit, a charging management circuit, a first current detection circuit, a first voltage detection circuit, a second voltage detection circuit and a second current detection circuit;

[0031] The output end of the CT coil interface 10 is electrically connected to the input end of the input protection circuit 20 to protect the subsequent circuit from damage. The output end of the input protection circuit 20 is electrically connected to the input end of the subsequent protection circuit 30. The rectifier circuit 40 is electrically connected between the output end of the subsequent protection circuit 30 and the input end of the switch power circuit. The output end of the switch power circuit is electrically connected to the charging management circuit. The first current detection circuit is arranged between the output end of the subsequent protection circuit 30 and the input end of the rectifier circuit 40. The first voltage detection circuit is arranged between the input end of the rectifier circuit 40 and the output end of the switch power circuit. The second voltage detection circuit is electrically connected to the output end of the switch power supply. The second current detection circuit is arranged between the output end of the switch power circuit and the charging management input end. The first current detection circuit and the first voltage detection circuit are isolated detection circuits, and the second current detection circuit and the second voltage detection circuit are non-isolated detection circuits. The input protection circuit 20 and the subsequent protection circuit 30 can avoid damage caused by excessive voltage at both ends of the circuit, greatly improving the service life of the equipment. Multi-level current and voltage detection, including an isolated detection circuit, hardware isolation can prevent voltage jumps or short circuits from affecting the entire circuit, thereby improving the operating safety of the overall equipment.

[0032] In this embodiment, the first input voltage sampling circuit 40 and the voltage regulating circuit 70 cooperate with the traditional PFC circuit to process the 220V AC power to improve the conversion efficiency. The specific structures of the first input voltage sampling circuit 40 and the voltage regulating circuit 70 will be further described below.

[0033] CT, the full name of which is Cur rent Transformer, is called current transformer in Chinese. This is a wireless power supply technology, and the principle of power supply is mainly based on electromagnetic induction. By arranging a CT (current transformer) coil on the power line, the coil induces current under the action of the magnetic field of the current, thereby generating a voltage that can be used by the equipment. This method can effectively solve the problem of power supply for equipment in complex environments or that is far away from the standard power supply and cannot be powered by cables. It is beneficial to reduce the wiring cost of the equipment and improve the installation flexibility of the equipment. The CT coil interface 10 is an interface for connecting the CT coil and other devices or circuits. It is usually designed as a pluggable interface, which is convenient for the installation and maintenance of the equipment, and can ensure the efficiency and stability of power transmission between different devices or circuits.

[0034] Further, such as Figure 2As shown, the input protection circuit 20 includes a varistor RV1, a gas discharge tube GDT2, a differential mode inductor L1, a voltage clamping circuit and an H-bridge circuit; the two ends of the varistor RV1, the gas discharge tube GDT2, the voltage clamping circuit and the H-bridge circuit are connected in parallel and are respectively connected to the two ends of the CT coil interface 10 to ensure the safe supply of power. The two ends of the differential mode inductor L1 are respectively connected to the gas discharge tube GDT2 and the voltage clamping circuit to form a stable circuit, which can provide timely processing for the situation where the input voltage is too high. The voltage clamping circuit includes a capacitor CY1, a resistor R10, a resistor R11, a diode D3 and a thyristor TR1; the capacitor CY1 and the resistor R10 are connected in series and are respectively connected to the two ends of the CT coil interface 10, one end of the resistor R11 is connected to the CT coil interface 10, and the other end is connected to the cathode of the diode D3, the anode of the diode D3 is connected to the G interface of the thyristor TR1, and the other two interfaces of the transistor are respectively connected to the two ends of the CT coil interface 10, and the common end of the resistor R11 and the capacitor CY1 is connected to the common end of the resistor R11 and the diode D3, so that the voltage clamping circuit protects other devices from damage by excessive voltage by controlling the conduction and disconnection of TR1.

[0035] The settings of RV1 and GDT2 are very important for circuit protection. RV1 is a varistor whose resistance value changes with the voltage. When the input voltage is too high, the current flowing through the varistor becomes larger, and RV1 clamps the voltage within a certain voltage range, absorbing energy from lightning or static electricity, and protecting the subsequent circuit from high voltage damage. GDT2 is a gas discharge tube and a commonly used overvoltage protection component. When the voltage at both ends exceeds its threshold voltage, GDT2 is short-circuited, and large impact energy can be leaked instantaneously through GDT2, thereby protecting the subsequent circuit. With these two protection devices, RV1 and GDT2, the circuit can effectively protect the subsequent circuit when encountering transient high-voltage impacts, preventing equipment damage caused by overvoltage.

[0036] like Figure 3 and Figure 4As shown, the post-stage protection circuit 30 includes components such as a common-mode inductor L3, a gas discharge tube GDT1, a differential-mode inductor L4, a bidirectional transient suppression diode D1, and a detection resistor R1, which are mainly used to protect sensitive components in the power supply circuit from damage caused by high voltage shock or sudden current, and improve the stability and safety of the circuit. The gas discharge tube GDT1 and the bidirectional transient suppression diode D1 are connected in parallel and then connected in series with the common-mode inductor L3. The two ends of the differential-mode inductor L4 are respectively connected to the gas discharge tube GDT1 and the bidirectional transient suppression diode D1. One end of the detection resistor R1 is connected to the bidirectional transient suppression diode D1, and the other end is connected to the rectifier circuit 40. Through the above settings, the common-mode inductor L3 can suppress common-mode noise and reduce interference in the power supply circuit. When the voltage exceeds a certain threshold, the gas discharge tube will be turned on instantaneously, and the voltage will be released instantly to protect the circuit and prevent the damage to the circuit caused by excessive voltage. The bidirectional transient suppression diode can suppress sudden changes in voltage in both directions, and cooperate with the gas discharge tube to provide bidirectional protection to prevent damage to the power supply circuit caused by excessively high or low voltage. The rectifier circuit 40 is a bridge rectifier circuit 40, which is composed of 4 diodes and realizes rectification through the unidirectional conductivity of the diodes.

[0037] In the power system, current detection is an important task, which is usually divided into two types: isolated and non-isolated. In an isolated switching power supply, an isolated current detection circuit is needed to detect the current on the isolated side. At present, the most common method in the industry is to use a current loop as a sensor to perform isolated current detection by detecting the induced current. However, this solution also faces some problems. For example, the input / output current ratio of the current loop is fixed, which limits its flexibility in dealing with changing currents; the current loop is large in size, so that the volume of the equipment cannot be further reduced; the most critical thing is that the current detection accuracy of the current loop is insufficient and cannot meet the needs of accurate detection. In this embodiment, a new type of isolated current detection circuit is used, which can have good detection accuracy, small size, and flexible response to current changes, significantly improving the effect and efficiency of current detection.

[0038] like Figure 5 and Figure 6As shown, the first current detection circuit includes chip U4, resistor R33 and resistor R35, and the chip U4 is an isolated ADC, whose model is AMC3306, and one end of the resistor R33 is connected to the back-stage protection circuit 30, and the other end is connected to the IN+ pin of the chip U4, and one end of the resistor R35 is connected to the back-stage protection circuit 30, and the other end is connected to the IN- pin of the chip U4. In the present embodiment, chip U4 is an isolated analog-to-digital converter (ADC). It contains an operational amplifier module and an ADC detection module inside, and the ADC quantization value of the corresponding input quantity can be directly obtained, and these values ​​are transmitted to the microcontroller (MCU) according to a predetermined timing through the output interface. It is worth mentioning that chip U4 has an internal isolation function, and its isolation voltage reaches more than 3KV. This method is usually converted into a voltage by detecting resistor R1, and then after passing through the operational amplifier, the voltage is amplified to a range suitable for MCU to receive, and then this voltage is sent to the ADC input port of the MCU, and the MCU reads the voltage level, thereby calculating the detection current. The resistance value of the detection resistor R1 is set to be small to reduce the power loss on the resistor R1. Therefore, the voltage across the resistor R1 is usually small, with a maximum of only tens of millivolts, so this voltage needs to be amplified before analog-to-digital conversion can be performed. Since the resistor R1 is located at the isolated front end of the switching power supply, and the MCU is located at the isolated back end of the switching power supply, in order to detect the current of R1, an isolated ADC acquisition solution is required.

[0039] The first voltage detection circuit includes a chip U3, a voltage divider circuit, a resistor R31 and a resistor R32. The chip U3 is an isolated ADC, and its model is AMC3336. This ADC can convert analog voltage signals into digital signals to facilitate subsequent digital processing and control. One end of the resistor R31 is connected to the voltage divider circuit, and the other end is connected to the IN+ pin of the chip U3. One end of the resistor R32 is connected to the voltage divider circuit, and the other end is connected to the IN- pin of the chip U3. The function of the voltage divider circuit shown is mainly to reduce the power supply voltage to the operating voltage range of the ADC chip, thereby avoiding overvoltage damage to the ADC chip. The voltage divider circuit includes a resistor R29, a resistor R121 and a resistor R34, wherein the resistor R29, the resistor R121 and the resistor R34 are connected in series, a common end of the resistor R29 and the resistor R12 is connected to the resistor R31, and a common end of the resistor R121 and the resistor R34 is connected to the resistor R32. This arrangement not only plays the role of impedance matching, but also can provide the ADC with a voltage signal that just fits its input level range.

[0040] Further, if Figure 7As shown, the charging management circuit includes a resistor R42, a resistor R52, a chip U5, a light emitting diode D15, a resistor R43, a field effect transistor Q2, a diode D13, an inductor L5, a resistor R47, a resistor R48, a resistor R49, a resistor R54, a field effect transistor Q3, a resistor R51, a resistor R53, a resistor R50 and a capacitor C42;

[0041] The charging management circuit mainly controls the charging current and voltage of the battery through the chip U5 to prevent the battery from being overcharged or over-discharged, thereby extending the service life of the battery and ensuring that it works in the optimal state. The resistor R42 and the resistor R52 are connected in series, and one end is connected to the power supply end, and the other end is grounded. The common end of the resistor R42 and the resistor R52 is connected to the MPPT pin of the chip U5. The cathode of the light-emitting diode D15 is connected to the CHRG pin of the chip U5, and the anode is connected to one end of the resistor R43. The other end of the resistor R43 is short-circuited to the power supply. The light-emitting diode can be used to indicate the battery charging status, which is convenient for users to check and understand the battery charging status. The gate of the field effect tube Q2 is connected to the DRV level of the chip U5, the source is connected to the power supply end, the drain is connected to the positive electrode of the diode D13, the negative electrode of the diode D13 is connected to one end of the inductor L5, and the other end of the inductor L5 is connected to the CSP pin of the chip U5 after passing through the resistor R47. After the resistor R49 and the resistor R54 are connected in series, one end is used to connect other chips, and the other end is grounded. The common end of the resistor R49 and the resistor R54 is connected to the FB pin of the chip U5. The drain of the field effect tube Q3 is connected to the COM pin of the chip U5, the source is connected to the GND pin of the chip U5, and the gate is connected to the resistor R51. One end of the resistor R53 is connected to the resistor R51, and the other end is grounded. After the resistor R50 and the capacitor C42 are connected in series, one end is connected to the COM pin of the chip U5, and the other end is connected to the GND pin of the chip U5. The settings of resistors R42, R52 and field effect transistor Q2 can adjust the maximum charging current and prevent the battery from overheating or thermal runaway caused by excessive charging current. Through the MPPT pin of chip U5, the cooperation of resistors R24, R52 and other components, the maximum power point tracking (MPPT) is realized. Even if the power supply voltage and current change, the system can always work at the maximum power point, thereby maximizing the efficiency of the power supply circuit. Through resistors R49, R54 and the FB pin of U5, the feedback of the charging voltage is realized, and the charging process can be monitored and controlled in real time, making the charging process safer and more stable.

[0042] In the CT power supply, the maximum power that can be obtained is related to the primary current. Different primary currents can obtain different maximum powers. And because the CT core will be affected by environmental factors (such as surface oxidation, environmental humidity, ambient temperature, etc.), the maximum power output of the system will also be affected as the use time goes by. To solve this problem, the charging management system needs to be able to identify the maximum output power of the power supply system. In this way, the power obtained by the CT can be maximized, and the system can work for a long time without overcharging or power loss. The commonly used lithium batteries on the market are mainly divided into ternary lithium batteries and lithium iron phosphate batteries. The charging voltages of these two batteries are not the same. Therefore, in order to make the charging management system compatible with these two batteries at the same time, the charging circuit needs to be able to adjust the maximum voltage of the battery charging. In the circuit, PIN 6 of chip U5 is designed as a battery voltage feedback pin. The maximum voltage of the battery charging can be adjusted through this feedback pin and the voltage divider network R49 and R54. This adjustment method can achieve constant voltage charging, and even if the battery type changes, it can ensure a stable charging voltage, and achieve compatibility with ternary lithium batteries and lithium iron phosphate batteries.

[0043] The maximum charging current of the charging management circuit is set by adjusting the resistor R37. Because if the charging current of the lithium battery is too large, it will cause the battery to overheat, or even thermal runaway and fire, which poses a serious threat to the safety of the system. Therefore, it is very important to set the maximum charging current. The formula is as follows: The maximum charging current is 0.12 / R37. In this way, the current size can be limited to protect the safety of the lithium battery and the system. To detect the maximum output power of the switching power supply, you can use the PIN 4 (MTTP) pin of the chip U5, which is modulated to 1.205V. Through the input voltage divider network connected to this pin, and through the set feedback divider network R42, R52, the voltage can be adjusted to monitor the maximum output power of the system. The maximum power point voltage is: V_MTTP = 1.205*(1+R42 / R52), this voltage needs to be slightly smaller than the constant voltage output voltage of the switching power supply.

[0044] The beneficial effects of the utility model are: an isolated current and voltage detection circuit is adopted, which reduces the measurement error, improves the operation efficiency of the circuit, and greatly reduces the size and weight of the device without reducing the performance of the device.

[0045] The above is a specific description of the preferred implementation of the utility model, but the invention of the utility model is not limited to the described embodiments. Technical personnel familiar with the field can also make various equivalent deformations or substitutions without violating the spirit of the utility model. These equivalent deformations or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A CT power supply circuit, characterized in that: It includes a CT coil interface, an input protection circuit, a post-stage protection circuit, a rectifier circuit, a switch power supply circuit, a charging management circuit, a first current detection circuit, a first voltage detection circuit, a second voltage detection circuit and a second current detection circuit; The output end of the CT coil interface is electrically connected to the input end of the input protection circuit to protect the subsequent circuit from damage. The output end of the input protection circuit is electrically connected to the input end of the subsequent protection circuit. The rectifier circuit is electrically connected between the output end of the subsequent protection circuit and the input end of the switching power supply circuit. The output end of the switching power supply circuit is electrically connected to the charging management circuit. The first current detection circuit is arranged between the output end of the subsequent protection circuit and the input end of the rectifier circuit. The first voltage detection circuit is arranged between the output end of the rectifier circuit and the input end of the switching power supply circuit. The second voltage detection circuit is electrically connected to the output end of the switching power supply. The second current detection circuit is arranged between the output end of the switching power supply circuit and the charging management input end. The first current detection circuit and the first voltage detection circuit are isolated detection circuits, and the second current detection circuit and the second voltage detection circuit are non-isolated detection circuits.

2. A CT power supply circuit according to claim 1, characterized in that: The first current detection circuit includes a chip U4, a resistor R33 and a resistor R35. The chip U4 is an isolated ADC, whose model is AMC3306. One end of the resistor R33 is connected to the post-stage protection circuit, and the other end is connected to the IN+ pin of the chip U4. One end of the resistor R35 is connected to the post-stage protection circuit, and the other end is connected to the IN- pin of the chip U4.

3. A CT power supply circuit according to claim 2, characterized in that: The first voltage detection circuit includes a chip U3, a voltage divider circuit, a resistor R31 and a resistor R32. The chip U3 is an isolated ADC, whose model is AMC3336. One end of the resistor R31 is connected to the voltage divider circuit, and the other end is connected to the IN+ pin of the chip U3. One end of the resistor R32 is connected to the voltage divider circuit, and the other end is connected to the IN- pin of the chip U3.

4. A CT power supply circuit according to claim 3, characterized in that: The voltage divider circuit includes a resistor R29, a resistor R121 and a resistor R34, which are connected in series, a common end of the resistor R29 and the resistor R12 is connected to the resistor R31, and a common end of the resistor R121 and the resistor R34 is connected to the resistor R32.

5. A CT power supply circuit according to claim 1, characterized in that: The charging management circuit includes a resistor R42, a resistor R52, a chip U5, a light emitting diode D15, a resistor R43, a field effect transistor Q2, a diode D13, an inductor L5, a resistor R47, a resistor R49, a resistor R54, a field effect transistor Q3, a resistor R51, a resistor R53, a resistor R50 and a capacitor C42; The resistor R42 and the resistor R52 are connected in series, one end of which is connected to the power supply end, and the other end is grounded. The common end of the resistor R42 and the resistor R52 is connected to the MPPT pin of the chip U5. The cathode of the light-emitting diode D15 is connected to the CHRG pin of the chip U5, and the anode is connected to one end of the resistor R43. The other end of the resistor R43 is short-circuited to the power supply. The gate of the field effect tube Q2 is connected to the DRV level of the chip U5, the source is connected to the power supply end, the drain is connected to the anode of the diode D13, the cathode of the diode D13 is connected to one end of the inductor L5, and the other end of the inductor L5 is connected through the resistor R47, connected to the CSP pin of chip U5, the resistor R49 and the resistor R54 are connected in series, one end of which is connected to the inductor L5, and the other end is grounded, the common end of the resistor R49 and the resistor R54 is connected to the FB pin of chip U5, the drain of the field effect transistor Q3 is connected to the COM pin of chip U5, the source is connected to the GND pin of chip U5, and the gate is connected to the resistor R51, one end of the resistor R53 is connected to the resistor R51, and the other end is grounded, the resistor R50 and the capacitor C42 are connected in series, one end is connected to the COM pin of chip U5, and the other end is connected to the GND pin of chip U5.

6. A CT power supply circuit according to claim 5, characterized in that: The charging management circuit also includes a resistor R37 and a resistor R48, one end of the resistor R37 is connected to the inductor L5, and the other end is connected to the BAT pin of the chip U5, the common end of the resistor R37 and the inductor L5 is connected to the CSP pin of the chip U5, and one end of the resistor R48 is connected to the BAT pin of the chip U5, and the other end is connected to the resistor R37.

7. A CT power supply circuit according to claim 1, characterized in that: The input protection circuit includes a varistor RV1, a gas discharge tube GDT2, a differential mode inductor L1, a voltage clamping circuit and an H-bridge circuit; The two ends of the varistor RV1, the gas discharge tube GDT2, the voltage clamping circuit and the H-bridge circuit are connected in parallel and are respectively connected to the two ends of the CT coil interface, and the two ends of the differential mode inductor L1 are respectively connected to the gas discharge tube GDT2 and the voltage clamping circuit.

8. A CT power supply circuit according to claim 7, characterized in that: The voltage clamping circuit includes a capacitor CY1, a resistor R10, a resistor R11, a diode D3 and a thyristor TR1; The capacitor CY1 and the resistor R10 are connected in series and are respectively connected to the two ends of the CT coil interface, one end of the resistor R11 is connected to the CT coil interface, and the other end is connected to the cathode of the diode D3, the anode of the diode D3 is connected to the G interface of the thyristor TR1, and the other two interfaces of the transistor are respectively connected to the two ends of the CT coil interface, and the common end of the resistor R11 and the capacitor CY1 is connected to the common end of the resistor R11 and the diode D3.

9. A CT power supply circuit according to claim 1, characterized in that: The post-stage protection circuit includes a common-mode inductor L3, a gas discharge tube GDT1, a differential-mode inductor L4, a bidirectional transient suppression diode D1 and a detection resistor R1; the gas discharge tube GDT1 and the bidirectional transient suppression diode D1 are connected in parallel and then in series with the common-mode inductor L3, the two ends of the differential-mode inductor L4 are respectively connected to the gas discharge tube GDT1 and the bidirectional transient suppression diode D1, one end of the detection resistor R1 is connected to the bidirectional transient suppression diode D1, and the other end is connected to the rectifier circuit.

10. A CT power supply circuit according to claim 1, characterized in that: The rectifier circuit is a bridge rectifier circuit, which is composed of four diodes and realizes rectification through the unidirectional conductivity of the diodes.

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