Induction power taking circuit and induction power taking equipment

Abstract

The utility model relates to the technical field of induction power taking, in particular to an induction power taking circuit and induction power taking equipment. The induction electricity taking circuit comprises an electricity taking CT, a chopping unit, a rectification unit, a voltage comparator and a direct current output end. AC voltage output by an electricity-taking CT in the induction electricity-taking circuit is converted into DC after passing through a rectification unit, and the AC voltage is supplied to a rear-end load; the voltage comparator compares the direct-current voltage output by the rectifying unit with the reference voltage, adjusts the duty ratio of PWM waves and controls the conduction time of the first switch and the second switch, high-frequency chopping of the alternating-current voltage output by the inductive power-taking CT is achieved, noise is not generated any more in the inductive power-taking working process, and the service life of the inductive power-taking CT is prolonged. Influence on surrounding residents is avoided, and user complaints are reduced; meanwhile, the rectified direct-current voltage can be limited not to exceed a preset value, and the direct-current voltage output by the power-taking CT is prevented from damaging a post-stage circuit.

Description

Technical Field

[0001] The present application relates to the technical field of inductive power extraction, and in particular to an inductive power extraction circuit and an inductive power extraction device. Background Art

[0002] Inductive power is often used to supply power to online power monitoring devices. It uses the principle of electromagnetic induction to induce energy from power cables to supply power monitoring devices. It is easy to deploy and is usually used in cable wells, cable tunnels or places where city power is not popular. During the inductive power process, the inductive power CT changes its magnetic field due to the current. The cutting surface of the inductive power CT generates a magnetic field at any time due to the change of current and is constantly attracted, generating relatively large vibration noise, especially under high current conditions. If the inductive power equipment is installed near residential areas, the noise will seriously affect the lives of surrounding residents and will also affect the normal operation of the online power monitoring equipment. Summary of the invention

[0003] In order to overcome the problems existing in the related technology, the present application provides an inductive power supply circuit and an inductive power supply device. The inductive power supply circuit does not generate any noise during the inductive power supply period, realizes the good application of the inductive power supply method in online power monitoring, and reduces complaints from users and surrounding residents.

[0004] According to a first aspect of an embodiment of the present application, an inductive power supply circuit is provided, comprising: a power supply CT, a chopper unit, a rectifier unit, a voltage comparator and a DC output terminal; the power supply CT is sleeved on a cable, a first end of the power supply CT is connected to a first input end of the rectifier unit, and a second end of the power supply CT is connected to a second input end of the rectifier unit; a first output end of the rectifier unit is connected to the DC output end, and a second output end of the rectifier unit is grounded; the DC output end is used to output DC power to a subsequent load;

[0005] The chopping unit includes a first switch and a second switch, wherein the first end of the first switch is connected to the first end of the power taking CT, and the second end thereof is grounded; the first end of the second switch is connected to the second end of the power taking CT, and the second end thereof is grounded; the voltage comparator includes a first voltage input end, a second voltage input end and a comparison output end, the first voltage input end of the voltage comparator is connected to the first output end of the rectifier unit, and is used to obtain a DC voltage signal output by the rectifier unit, the second voltage input end of the voltage comparator is connected to a reference voltage source, and is used to obtain a reference voltage signal, and the comparison output end of the voltage comparator is respectively connected to the controlled ends of the first switch and the second switch.

[0006] In an optional embodiment, the first switch and the second switch are used to perform high-frequency chopping on the alternating current output by the power-taking CT, and the switching frequency of the first switch and the second switch is greater than 20 KHz.

[0007] In an optional embodiment, the first switch is a MOSFET tube or a thyristor; the second switch is a MOSFET tube or a thyristor.

[0008] In an optional embodiment, the rectification unit includes a first diode, a second diode, a third diode and a fourth diode; the four diodes form a full-bridge rectification circuit.

[0009] In an optional embodiment, it further includes a filter capacitor connected between the rectifier unit and the DC output terminal;

[0010] The first end of the filter capacitor is connected to the first output end of the rectifier unit, and the second end of the filter capacitor is connected to the second output end of the rectifier unit.

[0011] In an optional embodiment, a DC conversion circuit connected between the filter capacitor and the DC output terminal is also included.

[0012] In an optional embodiment, the power supply CT is an open structure.

[0013] According to a second aspect of the embodiments of the present application, an inductive power extraction device is provided, comprising the inductive power extraction circuit described in the above embodiments.

[0014] According to the technical solution in the above-mentioned embodiment of the present application, the AC voltage output by the power taking CT in the inductive power taking circuit is converted into DC after passing through the rectifier unit to supply power to the rear-end load, the DC voltage output by the rectifier unit is compared with the reference voltage through a voltage comparator, the duty cycle of the PWM wave is adjusted, and the conduction time of the first switch and the second switch is controlled to realize high-frequency chopping of the AC voltage output by the inductive power taking CT, so that no noise is generated during the operation of the inductive power taking, thus avoiding affecting the surrounding residents and reducing user complaints; at the same time, the DC voltage after rectification can be limited not to exceed a preset value to prevent the DC voltage output by the power taking CT from damaging the subsequent circuit.

[0015] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application.

[0016] For better understanding and implementation, the present application is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the installation of the induction power CT provided in the embodiment of the present application;

[0018] Figure 2 A schematic diagram of the structure of the induction power supply circuit provided in the embodiment of the present application;

[0019] Figure 3 A waveform diagram of the inductive power collection process provided in an embodiment of the present application.

[0020] Reference numerals: T1, power supply CT; L1, cable; 10, chopper unit; 20, rectifier unit; 30, conversion circuit; S1, first switch; S2, second switch; D1, first diode; D2, second diode; D3, third diode; D4, fourth diode; C1, first capacitor; Vo, DC output terminal; U1, voltage comparator. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0023] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0024] According to a first aspect of an embodiment of the present application, an inductive power supply circuit is provided, which is applied to an inductive power supply device, which is used to supply power to a power monitoring device and is usually applied to cable wells, cable tunnels or places where mains electricity is not widely used.

[0025] like Figure 1 , Figure 2As shown, CT is the abbreviation of Current Transformer, that is, current transformer. In this embodiment, power is taken through the power CT. The power CTT1 is an open structure. The power CTT1 is put on the cable L1. When the current passes through the cable L1, the power CTT1 outputs an AC voltage according to the principle of electromagnetic induction. In this way, the electric energy on the cable L1 is obtained and transferred by inductive power taking. The iron core of the power CTT1 is wrapped with copper wire and placed in the shell, and then epoxy resin is poured. After the epoxy resin is cured, the power CT is cut into two halves; during installation, the power CTT1 is put on the cable L1, and the two cut surfaces are matched and fastened with stainless steel tie. Cable induction power taking will generate vibration noise. The magnitude of the vibration noise is determined by the flatness of the cut surface of the power CT and the magnitude of the cable current. Usually, physical means are used to reduce the noise, such as making the flatness of the cut surface of the power CT perfect to reduce the vibration noise. However, when the cable current is large, it will still generate large noise. In this case, the present application invents a zero-noise induction power supply circuit and device based on the principles and characteristics of the induction power supply CT, which is introduced in detail below.

[0026] like Figure 2 As shown, the inductive power circuit includes: a power supply CTT1, a chopper unit 10, a rectifier unit 20, a voltage comparator U1 and a DC output terminal Vo.

[0027] The first end of the power taking CTT1 is connected to the first input end of the rectifier unit 20, and the second end of the power taking CTT1 is connected to the second input end of the rectifier unit 20; the rectifier unit 20 is used to convert AC power into DC power, the first output end of the rectifier unit 20 is connected to the DC output end Vo, and the second output end of the rectifier unit 20 is grounded; the DC output end Vo is used to output DC power to the subsequent load.

[0028] The chopping unit 10 is used to chop the high-frequency alternating current output by the power taking CTT1 to avoid noise generated during inductive power taking, and at the same time limit the output voltage to a preset value to prevent damage to the subsequent circuit.

[0029] The chopper unit 10 includes a first switch S1 and a second switch S2, wherein the first end of the first switch S1 is connected to the first end of the power source CTT1, and the second end thereof is grounded; the first end of the second switch S2 is connected to the second end of the power source CTT1, and the second end thereof is grounded; the voltage comparator U1 includes a first voltage input end, a second voltage input end and a comparison output end, the first voltage input end of the voltage comparator U1 is connected to the first output end of the rectifier unit 20, for obtaining a DC voltage signal output by the rectifier unit 20, the second voltage input end of the voltage comparator U1 is connected to a reference voltage source, for obtaining a reference voltage signal, and the comparison output end of the voltage comparator U1 is respectively connected to the controlled ends of the first switch S1 and the second switch S2. The voltage comparator U1 adjusts the duty cycle of the PWM wave according to the detected DC voltage signal and the reference voltage signal, thereby forming a feedback closed loop to control the duty cycle of the first switch S1 and the second switch S2, that is, to control the conduction time of the two switches, thereby realizing high-frequency chopping. The sine wave is divided into many small pieces by chopping, so that the energy of each core impact will be greatly reduced to prevent noise.

[0030] The technical solution in the above-mentioned embodiment of the present application compares the DC voltage output by the rectifier unit with the reference voltage through a voltage comparator, adjusts the duty cycle of the PWM wave, controls the conduction time of the first switch and the second switch, and realizes high-frequency chopping of the AC voltage output by the inductive power CT, so that no noise is generated during the operation of the inductive power supply, thus avoiding affecting the surrounding residents and reducing user complaints; at the same time, the DC voltage after rectification can be limited to not exceed a preset value, so as to prevent the DC voltage output by the power supply CT from damaging the subsequent circuit.

[0031] The first switch S1 and the second switch S2 are used to perform high-frequency chopping on the alternating current output by the power taking CT. Optionally, the switching frequency of the first switch S1 and the second switch S2 is greater than 20 KHz.

[0032] According to the principle of electromagnetic transformation, when the cable passes current, it will generate a magnetic field and magnetic force. Since there is an iron core in the power CT, the magnetic force makes the iron cores of the power CT attract each other. The magnitude of the magnetic field force changes with the change of current. The greater the current, the greater the magnetic field force. Figure 3As shown, the current passing through the power cable is a 50 / 60Hz sine wave, so the magnetic field force will change with the sine wave value of the current. When the current passes through zero, the current is zero and the magnetic field force is zero; when the current reaches the peak of the sine wave, the current value is the largest and the magnetic field force is also the largest. The iron core is constantly attracted as the sine wave of the current changes. The attraction of the iron core will produce vibration noise of impact. The frequency of the iron core attraction is twice the frequency of the current. The current goes from zero point to the peak of the previous cycle, then to zero point, then to the peak of the next cycle, and then back to zero point. From zero point to peak and then to zero point, the current energy area is relatively large, so the magnetic field force generated by the current is also large, and the noise of the iron core impact is greater. The high frequency control switch is on and off. When the drive waveform is high level, the two switches are connected, and when it is low level, the two switches are disconnected. When the two switches are turned on, the output of the power CT is directly short-circuited, and the output voltage is zero at this time. When the two switches are disconnected, the output of the power CT returns to normal. By chopping, the sine wave is divided into many small pieces, so that the energy of each core impact will be greatly reduced. At the same time, high frequency (>20KHz) control is used to achieve the frequency of the impact exceeding the frequency range audible to the human ear (20~20KH), thus achieving zero noise operation of the power CT.

[0033] Optionally, the first switch S1 is a MOSFET tube or a thyristor; the second switch S2 is a MOSFET tube or a thyristor.

[0034] Optionally, the rectifier unit 20 includes a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4; the anode of the first diode D1 is connected to the first output terminal of the power taking CT, and is connected to the cathode of the third diode D3, the cathode of the first diode D1 is connected to the cathode of the second diode D2, and is connected to the DC output terminal Vo, the anode of the second diode D2 is connected to the second input terminal of the power taking CT, and is connected to the cathode of the fourth diode D4, the anode of the fourth diode D4 is connected to the anode of the third diode D3 and then grounded, and the four diodes form a full-bridge rectifier circuit to realize the rectification of the alternating current output by the power taking CT.

[0035] In one embodiment, the inductive power circuit also includes a filter capacitor C1 connected between the rectifier unit 20 and the DC output terminal Vo; the first end of the filter capacitor C1 is connected to the first output terminal of the rectifier unit 20, and the second end is connected to the second output terminal of the rectifier unit 20, for filtering out clutter noise.

[0036] Optionally, the inductive power supply circuit further includes a DC conversion circuit 30 connected between the filter capacitor C1 and the DC output terminal Vo, for providing a DC power supply to a subsequent circuit.

[0037] According to the technical solution in the above-mentioned embodiment of the present application, the AC voltage output by the power taking CT in the inductive power taking circuit is converted into DC after passing through the rectifier unit to supply power to the rear-end load, the DC voltage output by the rectifier unit is compared with the reference voltage through a voltage comparator, the duty cycle of the PWM wave is adjusted, and the conduction time of the first switch and the second switch is controlled to realize high-frequency chopping of the AC voltage output by the inductive power taking CT, so that no noise is generated during the operation of the inductive power taking, thus avoiding affecting the surrounding residents and reducing user complaints; at the same time, the DC voltage after rectification can be limited not to exceed a preset value to prevent the DC voltage output by the power taking CT from damaging the subsequent circuit.

[0038] According to a second aspect of an embodiment of the present application, an inductive power supply device is provided, comprising the inductive power supply circuit in the above embodiment, and the device is used to supply power to a back-end online power monitoring device or other power-consuming equipment.

[0039] The inductive power collection circuit in the inductive power collection device recorded in this embodiment has the same structure as the inductive power collection circuit recorded in the above embodiment, realizes the same function, can solve the same technical problems, and produces the same technical effects. Therefore, some structures of the inductive power collection circuit are not described in detail in this embodiment, and the contents not recorded in this embodiment can refer to the contents recorded in the above embodiment.

[0040] Note that the above are only preferred embodiments of the present application and the technical principles used. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present application. Therefore, although the present application is described in more detail through the above embodiments, the present application is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. An induction power circuit, characterized in that: include: A power CT, a chopper unit, a rectifier unit, a voltage comparator and a DC output terminal; the power CT is sleeved on the cable, the first end of the power CT is connected to the first input end of the rectifier unit, and the second end of the power CT is connected to the second input end of the rectifier unit; the first output end of the rectifier unit is connected to the DC output end, and the second output end of the rectifier unit is grounded; the DC output end is used to output DC power to the subsequent load; The chopping unit includes a first switch and a second switch, wherein the first end of the first switch is connected to the first end of the power taking CT, and the second end thereof is grounded; the first end of the second switch is connected to the second end of the power taking CT, and the second end thereof is grounded; the voltage comparator includes a first voltage input end, a second voltage input end and a comparison output end, the first voltage input end of the voltage comparator is connected to the first output end of the rectifier unit, and is used to obtain a DC voltage signal output by the rectifier unit, the second voltage input end of the voltage comparator is connected to a reference voltage source, and is used to obtain a reference voltage signal, and the comparison output end of the voltage comparator is respectively connected to the controlled ends of the first switch and the second switch.

2. The induction power supply circuit according to claim 1, characterized in that: The first switch and the second switch are used to perform high-frequency chopping on the alternating current output by the power-taking CT, and the switching frequency of the first switch and the second switch is greater than 20 KHz.

3. The induction power supply circuit according to claim 2, characterized in that: The first switch is a MOSFET tube or a thyristor; the second switch is a MOSFET tube or a thyristor.

4. The induction power supply circuit according to claim 1, characterized in that: The rectifying unit comprises a first diode, a second diode, a third diode and a fourth diode; the four diodes form a full-bridge rectifying circuit.

5. The induction power supply circuit according to claim 1, characterized in that: It also includes a filter capacitor connected between the rectifier unit and the DC output terminal; The first end of the filter capacitor is connected to the first output end of the rectifier unit, and the second end of the filter capacitor is connected to the second output end of the rectifier unit.

6. The inductive power supply circuit according to claim 5, characterized in that: It also includes a DC conversion circuit connected between the filter capacitor and the DC output terminal.

7. The inductive power supply circuit according to claim 1, characterized in that: The power taking CT is an open structure.

8. An induction power supply device, characterized in that: It comprises the induction power extraction circuit as described in any one of claims 1 to 7.

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