An electromagnetic isolation circuit and an electrical energy measuring device

Abstract

This utility model provides an electromagnetic isolation circuit and an electrical energy measurement device, relating to the technical field of electronic circuits. It includes: a filtering module, an isolation transformer drive module, an EMI suppression module, a transformer module, a rectifier module, and a voltage regulator module. The filtering module filters a first power supply. The isolation transformer drive module generates a primary-side power supply based on the filtered first power supply, which is then input to the transformer module. The EMI suppression module suppresses common-mode interference on the primary-side power supply. The transformer module converts the suppressed primary-side power supply into a secondary-side power supply with a preset ratio. The rectifier module rectifies the secondary-side power supply to obtain a rectified power supply. The voltage regulator module regulates the rectified power supply to obtain a second power supply, which powers the load. This invention solves the technical problem of instability in isolation circuits under strong magnetic environments, achieving high stability and safety.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuit technology, and in particular to an electromagnetic isolation circuit and an electrical energy measuring device. Background Technology

[0002] In electricity meter power supply circuits, linear transformers or switching power supply modules are typically used to independently power the main functional modules such as the metering circuit module, communication circuit module, and main control circuit module. Each circuit module needs to be isolated from the others. Due to the size of the transformer and the space limitations of the meter casing, the transformer output windings generally do not exceed three. However, when more than three circuit modules require isolated power supply, low-power circuit modules with small load change rates are usually selected and powered by isolated DC-DC (Direct Current to Direct Current) circuits. While commercially available DC / DC power supply modules are commonly used to build the power supply circuit, and this circuit is suitable for most operating scenarios, in strong magnetic environments (greater than 200mT), general-purpose DC / DC modules may experience instability, such as continuous restarting.

[0003] Therefore, existing technologies still need to be improved and enhanced. Summary of the Invention

[0004] The purpose of this invention is to provide an electromagnetic isolation circuit and an electrical energy measuring device, so as to solve the technical problem of unstable operation of isolation circuits under strong magnetic environment in the prior art.

[0005] In a first aspect, embodiments of this application provide an electromagnetic isolation circuit, including:

[0006] Filtering module, isolation transformer drive module, EMI suppression module, transformer module, rectifier module, and voltage regulator module;

[0007] The transformer module is connected to the isolation transformer drive module, the EMI suppression module and the rectifier module respectively. The filter module and the isolation transformer drive module are also connected to the first power supply and the first power supply ground respectively. The rectifier module and the voltage regulator module are also connected to the second power supply and the second power supply ground respectively. The EMI suppression module is also connected to the first power supply ground and the second power supply ground respectively.

[0008] The filtering module is used to filter the first power supply; the isolation transformer drive module is used to generate a primary-side power supply based on the filtered first power supply, which is then input to the transformer module; the EMI suppression module is used to suppress common-mode interference of the primary-side power supply; the transformer module is used to convert the suppressed primary-side power supply into a secondary-side power supply with a preset ratio; the rectification module is used to rectify the secondary-side power supply to obtain a rectified power supply; and the voltage regulation module is used to regulate the rectified power supply to obtain the second power supply, which is then used to power the load.

[0009] In some embodiments, the EMI suppression module includes: a first EMI suppression unit and a second EMI suppression unit; the first EMI suppression unit is connected to the isolation transformer drive module, the transformer module, and the first power ground, respectively; the second EMI suppression unit is connected in series between the first power ground and the second power ground;

[0010] The first EMI suppression unit is used to suppress common-mode interference of the primary power supply; the second EMI suppression unit is used to suppress common-mode interference of the second power supply to reduce electromagnetic interference to the load.

[0011] In some embodiments, the isolation transformer drive module includes: a first switching unit, a second switching unit, and a drive unit; the drive unit is connected to the first switching unit and the second switching unit respectively, and the first switching unit and the second switching unit are respectively connected to the first power supply, the first power supply ground, and the transformer module.

[0012] The drive unit is used to provide periodic switching control signals to the first switching unit and the second switching unit; the first switching unit and the second switching unit are used to control the primary power supply to be alternately input into the transformer module in opposite directions according to the periodic switching control signals, so as to obtain the secondary power supply in the corresponding direction.

[0013] In some embodiments, the first switching unit includes: a first switching transistor and a second switching transistor;

[0014] The first terminal of the first switching transistor is connected to the first power supply ground, the second terminal of the first switching transistor is connected to the third terminal of the second switching transistor and the transformer module, and the third terminal of the first switching transistor is connected to the drive unit.

[0015] The first end of the second switching transistor is connected to the first power supply, the third end of the second switching transistor is connected to the transformer module, and the second end of the second switching transistor is connected to the drive unit.

[0016] In some embodiments, the second switching unit includes a third switching transistor and a fourth switching transistor;

[0017] The first terminal of the third switch is connected to the first power ground, the third terminal of the third switch is connected to the second terminal of the fourth switch and the transformer module, and the second terminal of the third switch is connected to the drive unit.

[0018] The first end of the fourth switching transistor is connected to the first power supply, the second end of the fourth switching transistor is connected to the transformer module, and the third end of the fourth switching transistor is connected to the drive unit.

[0019] In some embodiments, the driving unit includes: an oscillation circuit; the oscillation circuit is connected to the first switching unit and the second switching unit respectively;

[0020] The oscillation circuit is used to provide the periodic switching control signal to control the first switching unit and the second switching unit to be turned on or off correspondingly within the period.

[0021] In some embodiments, the rectifier module includes: a first rectifier unit and a second rectifier unit; the first rectifier unit is connected to the second rectifier unit, and both the first rectifier unit and the second rectifier unit are respectively connected to the transformer module and the voltage regulator module;

[0022] The first rectifier unit is used to rectify the secondary power supply in the first direction to supply power to the load; the second rectifier unit is used to rectify the secondary power supply in the second direction to supply power to the load.

[0023] In some embodiments, the first rectifier unit includes: a first diode and a second diode;

[0024] After the anode of the first diode and the cathode of the second diode are connected, they are then connected to the transformer module. The cathode of the first diode is connected to the second power supply, and the anode of the second diode is connected to the ground of the second power supply.

[0025] In some embodiments, the second rectifier unit includes: a third diode and a fourth diode;

[0026] The anode of the third diode and the cathode of the fourth diode are connected together, and then connected to the transformer module. The cathode of the third diode is connected to the second power supply, and the anode of the fourth diode is connected to the ground of the second power supply.

[0027] Secondly, embodiments of this application provide an electrical energy measuring device, including a PCB board, on which an electromagnetic isolation circuit as described above is provided.

[0028] The electromagnetic isolation circuit and power measurement equipment provided by this utility model have the characteristics of stable operation in strong magnetic environment, strong electromagnetic isolation effect and high energy transmission efficiency, and high safety. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a circuit diagram of a common isolated DC-DC circuit;

[0031] Figure 2 A framework diagram of an electromagnetic isolation circuit provided in an embodiment of this utility model;

[0032] Figure 3 A circuit diagram of an electromagnetic isolation circuit provided in an embodiment of this utility model;

[0033] Figure 4 A circuit diagram of an isolation transformer drive module in an electromagnetic isolation circuit provided in an embodiment of this utility model.

[0034] Icons: 100 - Filtering module; 200 - Isolation transformer drive module; 210 - First switching unit; 220 - Second switching unit; 230 - Drive unit; 231 - Oscillation circuit; 300 - EMI suppression module; 310 - First EMI suppression unit; 320 - Second EMI suppression unit; 400 - Transformer module; 500 - Rectifier module; 510 - First rectifier unit; 520 - Second rectifier unit; 600 - Voltage regulator module; C1 - First capacitor; C2 - Second capacitor; C3 - Third capacitor; C4 - Fourth capacitor; C5 - Fifth capacitor; C6 - Sixth capacitor; C7 - Seventh capacitor; S1 - First switching transistor; S2 - Second switching transistor; S3 - Third switching transistor; S4 - Fourth switching transistor; D1 - First diode; D2 - Second diode; D3 - Third diode; D4 - Fourth diode. Detailed Implementation

[0035] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0036] The components of the embodiments of this application described and illustrated in the accompanying drawings can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of this application provided in the drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0037] In the following text, the terms "comprising," "having," and their cognates, which may be used in various embodiments of this application, are intended only to indicate a particular feature, number, step, operation, element, component, or combination thereof, and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or adding the possibility of one or more combinations thereof. Furthermore, the terms "first," "second," "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0038] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of this application pertain. Terms (such as those defined in commonly used dictionaries) shall be interpreted as having the same meaning as in their contextual meaning in the relevant technical field and shall not be construed as having an idealized or overly formal meaning, unless clearly defined in the various embodiments of this application.

[0039] The design scheme of the power frequency identification method is described below through some specific embodiments.

[0040] Please see Figure 1 In existing isolated DC-DC circuits, the high-frequency switching circuit inside the isolated DC-DC power module U0 converts the input 5V DC power (corresponding to...) into a DC-DC converter. Figure 2 The VCC in the middle is converted to an isolated 5V (corresponding to...). Figure 2 The circuit outputs VCC1 and uses PWM modulation technology to transfer energy. However, existing isolated DC-DC circuits can become unstable in strong magnetic environments.

[0041] Then please see Figure 2 This application provides an electromagnetic isolation circuit, including:

[0042] The system includes a filter module 100, an isolation transformer drive module 200, an EMI suppression module 300, a transformer module 400, a rectifier module 500, and a voltage regulator module 600.

[0043] The transformer module 400 is connected to the isolation transformer drive module 200, the EMI suppression module 300, and the rectifier module 500, respectively. The filter module 100 and the isolation transformer drive module 200 are also connected to the first power supply and the first power supply ground, respectively. The rectifier module 500 and the voltage regulator module 600 are also connected to the second power supply and the second power supply ground, respectively. The EMI suppression module 300 is also connected to the first power supply ground and the second power supply ground, respectively.

[0044] The filter module 100 is used to filter the first power supply; the isolation transformer drive module 200 is used to generate a primary-side power supply based on the filtered first power supply, which is then input to the transformer module 400; the EMI suppression module 300 is used to suppress common-mode interference of the primary-side power supply; the transformer module 400 is used to convert the suppressed primary-side power supply into a secondary-side power supply with a preset ratio; the rectifier module 500 is used to rectify the secondary-side power supply to obtain a rectified power supply; and the voltage regulator module 600 is used to regulate the rectified power supply to obtain a second power supply for powering the load.

[0045] EMI (Electromagnetic Interference) refers to electromagnetic interference. The preset ratio is related to the turns ratio of the transformer module 400. If the turns ratio is 5:1, then the preset ratio is 1 / 5, that is, the preset ratio = 1 / N, where N is the turns ratio. If the primary winding is marked as N1 and the secondary winding as N2, then N = N1 / N2.

[0046] Exemplarily, in this application, the filter module 100 regulates and filters the first power supply. Then, the isolation transformer drive module 200 generates a suitable drive signal, i.e., the primary-side power supply, based on the regulated and filtered first power supply to control the current flow in the input transformer module 400.

[0047] Meanwhile, the EMI suppression module 300 filters the primary power supply to suppress EMI, mainly common-mode interference, thereby protecting the normal operation of the circuit and meeting electromagnetic compatibility (EMC) requirements.

[0048] Then, the suppressed primary power supply is transformed into a secondary power supply with a preset ratio by the transformer module 400. After that, the secondary power supply is rectified by the rectifier module 500 to obtain rectified power; and then the rectified power supply is regulated by the voltage regulator module 600 to obtain a second power supply to power the load.

[0049] It is understood that in this application, the isolation transformer drive module 200 generates the primary-side power supply based on the filtered first power supply to control the current direction in the transformer module 400, preventing interference from the high-voltage side to the low-voltage side, thereby achieving efficient energy transmission and electrical isolation. Simultaneously, on the input side of the transformer module 400, the filter module 100 filters the first power supply and the EMI suppression module 300 suppresses common-mode interference; and on the output side of the transformer module 400, the rectifier module 500 rectifies the secondary-side power supply and the voltage regulator module 600 regulates the voltage, thereby further improving the system's safety and anti-interference capability.

[0050] Furthermore, the rectifier module 500 is also used to prevent current from the load from feeding back to the secondary side of the transformer, i.e., to prevent reverse current, thereby effectively ensuring circuit safety.

[0051] In one implementation method, please refer to Figure 3 The filter module 100 includes: a first capacitor C1, a second capacitor C2, and a third capacitor C3; the first capacitor C1, the second capacitor C2, and the third capacitor C3 are connected in parallel between the first power supply and the first power supply ground.

[0052] In one implementation, the isolation transformer drive module 200 includes: a first switching unit 210, a second switching unit 220, and a drive unit 230; the drive unit 230 is connected to the first switching unit 210 and the second switching unit 220 respectively, and both the first switching unit 210 and the second switching unit 220 are connected to a first power supply (corresponding to...). Figure 3 VDD in the middle), first power ground (corresponding to) Figure 3 The GND in the transformer module 400 is connected to the transformer module 400.

[0053] The drive unit 230 is used to provide periodic switching control signals to the first switching unit 210 and the second switching unit 220; the first switching unit 210 and the second switching unit 220 are used to control the primary power supply to be alternately input into the transformer module 400 in opposite directions according to the periodic switching control signals, so as to obtain the secondary power supply in the corresponding direction; the first switching unit 210 is used to control the primary power supply to be input into the transformer module 400 in a first direction according to the switching control signal of the first half cycle, so as to obtain the secondary power supply in the first direction; the second switching unit 220 is used to control the primary power supply to be input into the transformer module 400 in a second direction according to the switching control signal of the second half cycle, so as to obtain the secondary power supply in the second direction.

[0054] Please refer to Figure 4 In this application, the isolation transformer drive module 200 can be a drive chip (corresponding to...) Figure 3U1 in the diagram is a type of isolated power transformer driver that suppresses the bias magnetization or saturation of the power transformer (i.e., transformer module 400), and has functions such as short-circuit protection and overcurrent detection. The periodic switching control signals input to the first switching unit 210 and the second switching unit 220 are complementary rectangular wave signals or square wave signals, so that the first switching unit 210 and the second switching unit 220 are complementaryly turned on.

[0055] Exemplarily, drive unit 230 provides periodic switching control signals to first switching unit 210 and second switching unit 220. Then, in this application, it can be controlled that first switching unit 210 is turned on and second switching unit 220 is turned off during the first half-cycle of the switching control signal. At this time, the primary power supply is input into the primary winding of transformer module 400 in a first direction (e.g., clockwise direction), and the secondary winding of transformer module 400 will also generate a secondary power supply in the same direction.

[0056] Secondly, in the second half of the switching control signal cycle, the first switching unit 210 is turned off and the second switching unit 220 is turned on. At this time, the primary power supply is input into the primary winding of the transformer module 400 in the second direction (e.g., counterclockwise). Therefore, the secondary winding of the transformer module 400 will also generate a secondary power supply in the same direction. The on / off states of the first switching unit 210 and the second switching unit 220 in this application are illustrative and are not specifically limited here.

[0057] It is understood that in this application, the driving unit 230 provides complementary periodic switching control signals to the first switching unit 210 and the second switching unit 220 respectively, so that the two units form a complementary conduction state, so that the primary side power supply is input to the transformer module 400 in the corresponding direction, and finally the secondary side module in the corresponding direction is obtained. This realizes the effective provision of driving signals to control the transformer module 400, which not only improves the efficiency and reliability of the system, but also provides the possibility for miniaturization and high frequency design.

[0058] In one embodiment, the driving unit 230 includes an oscillation circuit 231; the oscillation circuit 231 is connected to a first switching unit 210 and a second switching unit 220 respectively. The first switching unit 210 includes a first switching transistor S1 and a second switching transistor S2. The second switching unit 220 includes a third switching transistor S3 and a fourth switching transistor S4.

[0059] The oscillation circuit 231 is used to provide periodic switching control signals to control the first switching unit 210 and the second switching unit 220 to be turned on or off correspondingly within the period.

[0060] The first terminal of the first switch S1 (corresponding to) Figure 4Pin 1 of the first switch S1 is connected to the first power supply ground, and the second terminal of the first switch S1 (corresponding to...) Figure 4 Pin 2 of S1 is connected to pin 3 of the second switch S2 (corresponding to pin 2 of S1). Figure 4 Pin 3 of S2 is connected to transformer module 400, and the third terminal of the first switching transistor S1 (corresponding to...) Figure 4 Pin 3 of the second switch S1 is connected to the drive unit 230; the first terminal of the second switch S2 (corresponding to...) Figure 4 Pin 1 of the second switch S2 is connected to the first power supply, and the third terminal of the second switch S2 (corresponding to...) Figure 4 Pin 3 of the second switch S2 is connected to the transformer module 400, and the second terminal of the second switch S2 (corresponding to...) Figure 4 Pin 2 of S2 is connected to the drive unit 230.

[0061] The first terminal of the third switch S3 (corresponding to) Figure 4 Pin 1 of the third switch S3 is connected to the first power supply ground, and the third terminal of the third switch S3 (corresponding to...) Figure 4 Pin 3 of S3 is connected to the second terminal of the fourth switch S4 (corresponding to...) Figure 4 Pin 2 of S4 is connected to transformer module 400, and the second terminal of the third switch S3 (corresponding to...) Figure 4 Pin 2 of S3 is connected to drive unit 230; the first terminal of the fourth switch S4 (corresponding to Figure 4 Pin 1 of the fourth switch S4 is connected to the first power supply, and the second terminal of the fourth switch S4 (corresponding to...) Figure 4 Pin 2 of the fourth switch S4 is connected to the transformer module 400, and the third terminal of the fourth switch S4 (corresponding to...) Figure 4 Pin 3 of S4 is connected to the drive unit 230.

[0062] The driving unit 230 can be an integrated oscillation module or oscillator, while the first switching unit 210 and the second switching unit 220 are two integrated pairs of N-type power MOSFETs (corresponding to...). Figure 4 S1 and S3) and P-type power MOSFETs (corresponding to Figure 4 (S2 and S4 in the diagram). The driver chip U1 includes 5 pins: VIN: power input pin; GND: chip ground pin; EN: enable pin, when the voltage of this pin is low, the driver chip stops working, and when this pin is high, the driver chip works; VB1: first output pin of the full-bridge driver stage; VB2: second output pin of the full-bridge driver stage.

[0063] Among them, the first switch S1 and the third switch S3 are both P-type MOSFETs or NPN transistors; the second switch S2 and the fourth switch S4 are both N-type MOSFETs or PNP transistors.

[0064] Therefore, the first terminal of the first switch S1 is the source of the P-type MOSFET or the emitter of the NPN transistor; the second terminal of the first switch S1 is the drain of the P-type MOSFET or the collector of the NPN transistor; and the third terminal of the first switch S1 is the gate of the P-type MOSFET or the base of the NPN transistor. The first terminal of the second switch S2 is the source of the P-type MOSFET or the emitter of the NPN transistor; the second terminal of the second switch S2 is the gate of the P-type MOSFET or the base of the NPN transistor; and the third terminal of the second switch S2 is the drain of the P-type MOSFET or the collector of the NPN transistor.

[0065] Exemplary, the oscillator circuit 231 provides complementary switching signals with precise timing and dead time, i.e., periodic switching control signals, to drive two pairs of switching transistors respectively, so that the current on the primary side can alternately push into and pull out the primary winding of the transformer (transformer module 400). The specific control process is as follows:

[0066] In the first half of the switching control signal cycle, the first switch S1 and the second switch S2 are complementaryly turned on, and the primary power supply is input to the primary winding of the transformer module 400 in the first direction. However, in the second half of the switching control signal cycle, the third switch S3 and the fourth switch S4 are complementaryly turned on, and the primary power supply is input to the primary winding of the transformer module 400 in the second direction.

[0067] Ultimately, a corresponding voltage is induced in the secondary winding of transformer T1, resulting in a secondary power supply, thus achieving voltage boosting or bucking. Furthermore, due to the isolation characteristics of transformer T1, the output voltage and input voltage of transformer T1 are isolated from each other.

[0068] In one implementation, the EMI suppression module 300 includes: a first EMI suppression unit 310 and a second EMI suppression unit 320; the first EMI suppression unit 310 is connected to the isolation transformer drive module 200, the transformer module 400 and the first power ground respectively; the second EMI suppression unit 320 is connected in series between the first power ground and the second power ground.

[0069] The first EMI suppression unit 310 is used to suppress common-mode interference of the primary power supply; the second EMI suppression unit 320 is used to suppress common-mode interference of the second power supply to reduce electromagnetic interference to the load.

[0070] As an example, after the isolation transformer drive module 200 generates the primary-side power supply, the first EMI suppression unit 310 filters the primary-side power supply to suppress common-mode interference and reduce the impact of radiated EMI.

[0071] Similarly, after the transformer module 400 generates the secondary power supply, the second EMI suppression unit 320 filters the secondary power supply to suppress common-mode interference. This is mainly achieved by utilizing the low impedance characteristics of capacitors for high-frequency signals to bypass common-mode interference signals to ground, thereby reducing the possibility of them propagating to subsequent circuits or the external environment.

[0072] In one implementation, the first EMI suppression unit 310 includes a fourth capacitor C4 and a fifth capacitor C5, which are EMI suppression capacitors capable of effectively reducing the impact of radiated EMI; the second EMI suppression unit 320 includes a sixth capacitor C6; the voltage regulator module 600 includes a seventh capacitor C7; one end of the fourth capacitor C4 is connected to the first output pin VB1 of the full-bridge driver stage of the driver chip U1 and the first end of the primary winding of the transformer T1, respectively; one end of the fifth capacitor C5 is connected to the second output pin VB2 of the full-bridge driver stage of the driver chip U1 and the second end of the primary winding of the transformer T1, respectively; the other ends of the fourth capacitor C4 and the fifth capacitor C5 are both connected to the first power supply ground. The sixth capacitor C6 is connected in series between the first power supply ground and the second power supply ground. The seventh capacitor C7 is connected in series between the second power supply ground and the second power supply ground.

[0073] In one implementation, the transformer module 400 is a transformer T1, which in this application is an SMD-4 packaged (a specific type of surface mount device (SMD) packaging technology) surface mount transformer. It is an isolation power transformer that can provide 2.5kVDC isolation capability and push-pull output. Its size of 5.5*7.3mm is much smaller than that of traditional transformers, making it very suitable for applications in space-constrained DIN rail energy meters.

[0074] In one implementation, the rectifier module 500 includes: a first rectifier unit 510 and a second rectifier unit 520; the first rectifier unit 510 is connected to the second rectifier unit 520, and both the first rectifier unit 510 and the second rectifier unit 520 are respectively connected to the transformer module 400 and the voltage regulator module 600.

[0075] The first rectifier unit 510 is used to rectify the secondary power supply in the first direction to supply power to the load; the second rectifier unit 520 is used to rectify the secondary power supply in the second direction to supply power to the load.

[0076] Exemplarily, after the transformer module 400 generates secondary power in the first direction, the first rectifier unit 510 rectifies the secondary power in the first direction to supply power to the load. Similarly, after the transformer module 400 generates secondary power in the second direction, the second rectifier unit 520 rectifies the secondary power in the second direction to supply power to the load.

[0077] It is understood that in this application, the first rectifier unit 510 and the second rectifier unit 520 are used to rectify the secondary power supply, making the second power supply more stable, thereby improving the stability of power supply and helping to ensure power safety.

[0078] In one embodiment, the first rectifier unit 510 includes a first diode D1 and a second diode D2; the second rectifier unit 520 includes a third diode D3 and a fourth diode D4.

[0079] After the anode of the first diode D1 and the cathode of the second diode D2 are connected, they are then connected to the transformer module 400. The cathode of the first diode D1 is connected to the second power supply (corresponding to...). Figure 3 The first diode (D1) is connected to the second power supply ground (corresponding to the second power supply ground). Figure 3 The GND1 connection is in the middle.

[0080] After the anode of the third diode D3 and the cathode of the fourth diode D4 are connected, they are then connected to the transformer module 400. The cathode of the third diode D3 is connected to the second power supply, and the anode of the fourth diode D4 is connected to the ground of the second power supply.

[0081] In this configuration, the first diode D1, the second diode D2, the third diode D3, and the fourth diode D4 are all Schottky diodes. Therefore, the first rectifier unit 510 and the second rectifier unit 520 each constitute bidirectional Schottky diodes, which have the characteristics of low cost and small size.

[0082] This application provides an electrical energy measuring device, including a PCB board, on which the electromagnetic isolation circuit described above is provided.

[0083] By way of example, the entire electromagnetic isolation circuit in this application uses small packaged devices, including a transformer driver chip (i.e., isolation transformer driver module 200) in an SOT23-5 package (a specification of a small surface mount transistor package) and a compact surface mount transformer (i.e. transformer module 400) in an SMD-4 package, and is equipped with simple peripheral circuits. It has the characteristics of small circuit space, low cost, strong magnetic resistance and strong stability (stable output in a strong magnetic environment greater than 200mT).

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. An electromagnetic isolation circuit, characterized in that, include: Filtering module, isolation transformer drive module, EMI suppression module, transformer module, rectifier module, and voltage regulator module; The transformer module is connected to the isolation transformer drive module, the EMI suppression module and the rectifier module respectively. The filter module is connected to the isolation transformer drive module. The rectifier module is connected to the voltage regulator module. The EMI suppression module is also connected to the first power ground of the primary circuit and the second power ground of the secondary circuit of the transformer module respectively. The filtering module is used to filter the first power supply; The isolation transformer drive module is used to generate a primary-side power supply based on the filtered first power supply, which is then input to the transformer module. The EMI suppression module is used to suppress common-mode interference of the primary-side power supply. The transformer module is used to convert the suppressed primary-side power supply into a secondary-side power supply with a preset ratio. The rectification module is used to rectify the secondary-side power supply to obtain a rectified power supply. The voltage regulation module is used to regulate the rectified power supply to obtain a second power supply, which is then used to power the load.

2. The electromagnetically isolated circuit of claim 1, wherein, The EMI suppression module includes: a first EMI suppression unit and a second EMI suppression unit; the first EMI suppression unit is connected to the isolation transformer drive module, the transformer module and the first power ground respectively; the second EMI suppression unit is connected in series between the first power ground and the second power ground; The first EMI suppression unit is used to suppress common-mode interference of the primary power supply; the second EMI suppression unit is used to suppress common-mode interference of the second power supply to reduce electromagnetic interference to the load.

3. The electromagnetically isolated circuit of claim 2, wherein, The isolation transformer drive module includes: a first switching unit, a second switching unit, and a drive unit; the drive unit is connected to the first switching unit and the second switching unit respectively, and the first switching unit and the second switching unit are respectively connected to the first power supply, the first power supply ground, and the transformer module; The drive unit is used to provide periodic switching control signals to the first switching unit and the second switching unit; the first switching unit and the second switching unit are used to control the primary power supply to be alternately input into the transformer module in opposite directions according to the periodic switching control signals, so as to obtain the secondary power supply in the corresponding direction.

4. The electromagnetically isolated circuit of claim 3, wherein, The first switching unit includes: a first switching transistor and a second switching transistor; The first terminal of the first switching transistor is connected to the first power supply ground, the second terminal of the first switching transistor is connected to the third terminal of the second switching transistor and the transformer module, and the third terminal of the first switching transistor is connected to the drive unit. The first end of the second switching transistor is connected to the first power supply, the third end of the second switching transistor is connected to the transformer module, and the second end of the second switching transistor is connected to the drive unit.

5. The electromagnetically isolated circuit of claim 4, wherein, The second switching unit includes: a third switching transistor and a fourth switching transistor; The first terminal of the third switch is connected to the first power ground, the third terminal of the third switch is connected to the second terminal of the fourth switch and the transformer module, and the second terminal of the third switch is connected to the drive unit. The first end of the fourth switching transistor is connected to the first power supply, the second end of the fourth switching transistor is connected to the transformer module, and the third end of the fourth switching transistor is connected to the drive unit.

6. The electromagnetically isolated circuit of claim 5, wherein, The driving unit includes an oscillation circuit; the oscillation circuit is connected to the first switching unit and the second switching unit respectively. The oscillation circuit is used to provide the periodic switching control signal to control the first switching unit and the second switching unit to be turned on or off correspondingly within the period.

7. The electromagnetically isolated circuit of claim 3, wherein, The rectifier module includes: a first rectifier unit and a second rectifier unit; the first rectifier unit is connected to the second rectifier unit, and both the first rectifier unit and the second rectifier unit are respectively connected to the transformer module and the voltage regulator module; The first rectifier unit is used to rectify the secondary power supply in the first direction to supply power to the load; the second rectifier unit is used to rectify the secondary power supply in the second direction to supply power to the load.

8. The electromagnetic isolation circuit according to claim 7, characterized in that, The first rectifier unit includes: a first diode and a second diode; After the anode of the first diode and the cathode of the second diode are connected, they are then connected to the transformer module. The cathode of the first diode is connected to the second power supply, and the anode of the second diode is connected to the ground of the second power supply.

9. The electromagnetic isolation circuit according to claim 8, characterized in that, The second rectifier unit includes: a third diode and a fourth diode; The anode of the third diode and the cathode of the fourth diode are connected together, and then connected to the transformer module. The cathode of the third diode is connected to the second power supply, and the anode of the fourth diode is connected to the ground of the second power supply.

10. An electrical energy measuring device, characterized by It includes a PCB board, wherein the PCB board is provided with an electromagnetic isolation circuit as described in any one of claims 1-9.

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