CN218727575U - Current measuring device and power supply change-over switch - Google Patents

Abstract

A current measuring device is provided. The current measuring device comprises at least one printed circuit board layer and a conductive path carrying a current to be measured; each of the at least one printed circuit board layer includes a first circuit board portion having a first planar coil disposed thereon and a second circuit board portion having a second planar coil disposed thereon; an electrically conductive path is arranged between the first planar coil and the second planar coil; and all of the first planar coils and the second planar coils of the at least one printed circuit board layer are electrically connected for electromagnetically inducing current in the conductive path. A power transfer switch is also provided.

Description

Current measuring device and power supply change-over switch

Technical Field

The utility model relates to a current measurement device and have current measurement device's power change over switch.

Background

Currently, in electrical applications such as electric meters or dual power transfer switches, it is necessary to use a current measuring circuit or a current sampling circuit in the current loop in which they are located. In particular, in the case of a dual power transfer switch having an electromagnet, a current measuring circuit or a current sampling circuit is also required to perform closed-loop control of the current in order to accurately control the magnitude of the current. For example, for sampling or measuring current, a sampling resistor is usually arranged in a current loop, which results in no electrical isolation between a current measuring circuit and a circuit where an electromagnet is arranged, so that an isolation device is inevitably required to be additionally arranged in the sampling circuit.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a current measurement device and have current measurement device's power transfer switch, it can make to have electrical isolation between the circuit at current measurement circuit and electro-magnet place to compact structure.

According to aspects of the present invention, a current measuring device is provided. The current measuring device comprises at least one printed circuit board layer and a conductive path carrying a current to be measured; each of the at least one printed circuit board layer includes a first circuit board portion having a first planar coil disposed thereon and a second circuit board portion having a second planar coil disposed thereon; an electrically conductive path is arranged between the first planar coil and the second planar coil; and all of the first planar coils and the second planar coils of the at least one printed circuit board layer are electrically connected for electromagnetically inducing current in the conductive path.

Optionally, the current measuring device further includes: a printed circuit board top layer located above the at least one printed circuit board layer and including a first surface metal shield area; and a printed circuit board bottom layer located below the at least one printed circuit board layer and including a second surface metal shielding region; a first surface metal shield region and a second surface metal shield region cover the first planar coil, the second planar coil, and the conductive path.

Alternatively, in the current measuring device, the first planar coil and the second planar coil are connected in series and wound in opposite directions, respectively.

Alternatively, in the current measuring device, the first planar coil and the second planar coil have a predetermined number of winding turns.

Optionally, in the current measuring device, the number of layers of the at least one printed circuit board layer is 2N, where N is an integer greater than 1, and the number of winding turns is greater than or equal to 6.

Optionally, in the current measuring device, the first surface metal shielding region and the second surface metal shielding region are lined with copper.

Alternatively, in the current measuring device, there is a groove or a dam between the conductive path and the first planar coil and the second planar coil on both sides thereof.

According to the utility model discloses an aspect still provides a power transfer switch, and power transfer switch includes: the current measuring device as described above; the switching device is provided with a control pole for controlling the switching device to be switched on and off, a first pole connected with the electromagnet driving mechanism and a second pole electrically connected with a conductive path of the current measuring device; and a control circuit, the input end of which is connected to the output end of the electromagnetic induction of the current measuring device and the output end of which is connected to the control electrode of the switching device, so as to maintain the current flowing through the electromagnet driving circuit.

According to the utility model discloses a according to each embodiment of each aspect, can realize carrying out electromagnetic induction effectively to the measuring electric current for electromagnetic induction's coil part can be with the conductive path electrical isolation. Furthermore, various embodiments have the advantage of a simple circuit design, a high immunity against electromagnetic radiation and external interference current signals, and a low cost. In addition, the current measuring circuit is combined with the power supply change-over switch, so that closed-loop control of the control circuit on the switching device can be realized, and the control circuit, the current measuring device and the switching device can be electrically isolated, so that the current measuring device and the switching device are independent from each other, the interference between the current measuring device and the switching device is reduced, and the noise is reduced.

Drawings

The aspects, features and advantages of the present invention will become more apparent and readily appreciated from the following description of the embodiments taken in conjunction with the accompanying drawings of which:

fig. 1A shows a side view of a current measurement device according to an embodiment of the invention;

fig. 1B showsbase:Sub>A cross-sectional view of the current measuring device of fig. 1A along linebase:Sub>A-base:Sub>A' according to an embodiment of the invention;

fig. 2A shows a side view of a current measurement device according to another embodiment of the present invention;

fig. 2B shows a perspective view from above of the current measuring device of fig. 2A according to another embodiment of the invention;

fig. 3 shows a perspective view of a current measuring device with a multilayer coil according to a further embodiment of the invention;

fig. 4 shows a schematic view of a current measuring device with a recess according to yet another embodiment of the present invention; and

fig. 5 shows a schematic diagram of a power transfer switch according to an embodiment of the invention.

Detailed Description

The present invention will be described in detail below with reference to exemplary embodiments thereof. The invention is not limited to the embodiments described herein, however, which may be embodied in many different forms. The described embodiments are intended to be merely thorough and complete and to fully convey the concept of the invention to those skilled in the art. Features of the various embodiments described may be combined with each other or substituted for each other unless expressly excluded or otherwise excluded in context.

Unless defined otherwise, technical or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," and similar terms in the description herein do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item preceding the word comprises the element or item listed after the word and its equivalent, but does not exclude other elements or items. The terms "coupled," "connected," or "connected," and the like, are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.

In a conventional current measuring device, for example, in a current measuring operation of an electricity meter, a current transformer or a PCB coil having a through hole in the middle is employed as the current measuring device, and a wire to be measured in three-phase four wires of an alternating current is passed through the through hole in the current transformer or the PCB coil. For example, current transformers are costly and occupy a large volume as a separate external device. It can be seen that the current measuring device may have the disadvantages of higher cost, larger volume, no good electromagnetic isolation effect, and the like.

In order to solve the technical problem, the utility model discloses an each embodiment provides simple structure, the volume is less and can have the current measurement device of electromagnetic isolation. Embodiments will be described in detail below with reference to the accompanying drawings.

Fig. 1A shows a side view of a current measurement device 100 according to an embodiment of the present invention. And fig. 1B showsbase:Sub>A cross-sectional view of the current measuring device 100 of fig. 1A along linebase:Sub>A-base:Sub>A' according to an embodiment of the invention. The current measuring device 100 comprises at least one printed circuit board layer 110 and a conductive path 120 carrying the current to be measured.

Each of the at least one printed circuit board layer 100 (fig. 1B, 110-1 for example) includes a first circuit board portion 112 and a second circuit board portion 114 (shown in dashed line box in fig. 1B), the first circuit board portion 112 having a first planar coil 116 disposed thereon, the second circuit board portion 112 having a second planar coil 118 disposed thereon. In some examples, the at least one printed circuit board layer 110 has a void (not labeled in the figures) between the first circuit board portion 112 and the second circuit board portion 114. It is noted that the at least one printed circuit board layer 110 may be formed from one or more printed circuit board layers stacked on top of each other. For example, all of the first planar coil 116 and the second planar coil 118 may be stacked on top of each other on the corresponding circuit board portion.

A conductive path 120 is disposed between the first planar coil 116 and the second planar coil 118. For example, the conductive path 120 may be electrically connected to a current loop to be measured and may be part of a wire in the current loop to be measured. Thus, the conductive path 120 may be a wire or other conductor under test in a current loop and carry the current to be measured, wherein the current to be measured I may be a time varying current I (t), such as 50Hz or 60Hz, a sinusoidal current with a current of 5A to several hundred a, preferably a current in the range of 20A to 40A. The utility model discloses a volume of awaiting measuring electric current is not limited to this.

For example, all of the first planar coils 116 and the second planar coils 118 of the at least one printed circuit board layer 110 are electrically connected for electromagnetically inducing the current I in the conductive path 120. Specifically, the first planar coil 116 and the second planar coil 118 electrically connected together may generate a time-varying magnetic field (H (t, x)) based on the time-varying current (i (t)), and may generate and measure an induced voltage signal based on the time-varying current and the time-varying magnetic field. That is, the induced voltage signal is associated with a time-varying current and may be output to subsequent control circuitry or other processing circuitry.

Fig. 2A shows a side view of a current measurement device 200 according to another embodiment of the present invention. And fig. 2B shows a perspective view from above of the current measurement device 200 of fig. 2A according to another embodiment of the present invention. Printed circuit board layer(s) 210, first circuit board portion 212, second circuit board portion 214, first planar coil 216, second planar coil 218, and conductive paths 220 in fig. 2A and 2B are the same as those two last digits of the reference numbers in fig. 1A and 1B, and thus are not repeated herein.

As shown in fig. 2A, current measurement device 200 also includes a printed circuit board top layer 230 and a printed circuit board bottom layer 240. The printed circuit board top layer 230 is located over at least one printed circuit board layer 210 and includes a first surface metal shield area 232. Also, the printed circuit board bottom layer 240 is located below the at least one printed circuit board layer and includes a second surface metal shielding region 242.

As shown in fig. 2B, the first surface metal shielding region 232 and the second surface metal shielding region 242 cover the first planar coil 216, the second planar coil 218 and the conductive path 220. Specifically, first surface metallic shielding region 232 and second surface metallic shielding region 242 may completely cover first planar coil 216, second planar coil 218, and conductive path 220 from the top and bottom, respectively. In other words, the projected area of the first surface metal shielding region 232 and the second surface metal shielding region 242 (not shown, which corresponds to the first surface metal shielding region 232) is greater than or equal to the projected area of the entire region formed by the first planar coil 216, the second planar coil 218, and the region containing the conductive path 220 therebetween. Therefore, electromagnetic interference caused by interference wires, particularly interference wires located above the top layer of the printed circuit board and below the bottom layer of the printed circuit board of the current measuring device shown in fig. 2A, can be effectively shielded by providing a completely covered surface metal shielding region.

In some embodiments, the first surface metal shielding region 232 and the second surface metal shielding region 242 may be lined with copper. The copper paving step can adopt a conventional ground paving method adopted in a printed circuit board, thereby realizing low-cost and high-efficiency electromagnetic shielding effect. The copper plating method in various embodiments may be implemented by various methods for plating metal on the printed circuit board, and the present application is not limited thereto. Optionally, the present invention may also adopt other metal materials, magnetic materials, etc. to lay the surface metal shielding regions 232, 242 to shield the electromagnetic interference.

Researchers found that simulation test results of an interfering wire/path with a distance of 10mm above the top layer 230 of the printed circuit board of the current measuring device shown in fig. 2A, induced voltage signals can reach mV magnitude when 100A, 50Hz current I passes through the conductive path 220; in contrast, when the interference wire/path passes 100A 50Hz current, the interference voltage is less than or equal to 1/40, even less than 1/100, even less than 1/1000 of the induced voltage signal. It can be seen that the current measuring device 200 described above can effectively shield the interference current.

Fig. 3 shows a perspective view of a current measuring device 300 with a multilayer coil 316, 318 according to a further embodiment of the invention. The first planar coil 316, the second planar coil 318 and the conductive path 320 in fig. 3 are the same as the elements with the same reference numerals in fig. 1A and 1B and fig. 2A and 2B, and therefore are not described again.

In some embodiments, in current measuring device 300, first planar coil 316 and second planar coil 318 are connected in series and wound in opposite directions, respectively. For example, the first planar coil 316 may be wound clockwise as shown, while the second planar coil 318 may be wound counterclockwise as shown, or vice versa. By arranging the windings in opposite directions, the induced signals generated by each coil on the measured wire between the first planar coil and the second planar coil can be added. Also, by arranging the windings in reverse, the interfering wires arranged at the sides of the first planar coil 316 and the second planar coil 318 of the current measuring device away from the conductive path 320 can be effectively shielded. Since the first planar coil 316 and the second planar coil 318 are wound in opposite directions on the same side as the interference wire when the interference wire is disposed at either outer side of the first planar coil 316 and the second planar coil 318, induced voltage signals generated at the two opposite coils caused by the interference wire are cancelled out each other, thereby effectively reducing the interference. In some examples, in current measuring device 300, first planar coil 316 and second planar coil 318 have a predetermined number of winding turns. In particular, in the current measuring device, the number of layers of at least one printed circuit board layer is 2N, where N is an integer greater than 1, and the number of winding turns is greater than or equal to 6 (fig. 3 exemplifies only that the number of winding turns is equal to 6, and the number of layers of the first planar coil and the second planar coil is equal to 4). Therefore, in the case where the top layer 230 including the printed circuit board and the bottom layer 240 including the printed circuit board as shown in fig. 2A are also implemented by the method of the printed circuit board, the total number of layers of the current measuring device 300 is 2n +2.

In some embodiments, according to the example of four printed circuit board layers as shown in fig. 3, each of all of the first planar coil 316 and the second planar coil 318 has a first end near the center and a second end far from the center, wherein the first end of the first planar coil located in the first printed circuit board layer is electrically connected to the second end of the first planar coil located in the second printed circuit board layer by a conductive via 350. The first end of the first planar coil located in the second printed circuit board layer is electrically connected to the second end of the first planar coil located in the third printed circuit board layer by a conductive via 350. The first end of the first planar coil located on the third printed circuit board layer is electrically connected to the second end of the first planar coil located on the fourth printed circuit board layer by conductive via 350, and the first end of the first planar coil located on the fourth printed circuit board layer is electrically connected to the first end of the second planar coil located on the fourth printed circuit board layer by conductive via 350, and so on. Through the above connection, all of the first planar coils 316 and all of the second planar coils 318 in the four printed circuit board layers are connected in series with each other and leave the second ends of the first planar coils located at the first printed circuit board layer and the second ends of the second planar coils located at the first printed circuit board layer to form a first output terminal and a second output terminal, thereby outputting the induced voltage signal. The foregoing shows only one exemplary coil connection manner, the connection manner of the present invention is not limited thereto, as long as all the first planar coils and all the second planar coils are connected in series, so that the induced signals of the tested wires between the first planar coils and the second planar coils are added via all the planar coils to generate induced voltage signals, and the induced signals of the tested wires in all the first planar coils and the induced signals of the tested wires in all the second planar coils are prevented from being mutually cancelled or partially cancelled. In some examples, the conductive vias 350 may be selected from through vias from the top printed circuit board layer to the bottom printed circuit board layer via at least one printed circuit board layer, buried vias through at least one printed circuit board layer and not through the top printed circuit board layer and the bottom printed circuit board layer, blind vias, or combinations thereof. For example, through vias for electrically connecting different layers may be used at the first and second ends of the first planar coil, respectively, and the electrical connection between the different through vias is achieved by routing at each printed circuit board layer. The current measuring device 300 may output the electromagnetically induced voltage signal via the first output terminal and the second output terminal for subsequent processing.

Researchers find that when the interference wire is 50mm away from the position right above the coil, 1000A of current flows through the interference wire for simulation, and the induced voltage of the coil is of uV magnitude or lower, so that even under the condition that the interference current is very large, the interference voltage is very small and can be ignored. In contrast, when the current I of the conductive path is 100A and 50Hz, the induced voltage signal is up to mV or even higher.

Fig. 4 shows a schematic view of a current measuring device 400 with a recess 460 according to yet another embodiment of the present invention. The first planar coil 416, the second planar coil 418 and the conductive path 420 in fig. 4 are the same as the last two digits of the reference numbers in fig. 1A and 1B, fig. 2A and 2B and fig. 3, and therefore, the description thereof is omitted.

For example, in the current measuring device 400, there is a recess 460 or a dam 460 between the conductive path 420 and the first planar coil 416 and the second planar coil 418 on both sides thereof, as indicated by the solid black rectangle in the figure. For example, the recess 460 of fig. 4 may have a cross-section with various geometric shapes, or the retaining wall of fig. 4 may be a protrusion with various geometric shapes, which is not limited by the present invention. For example, the width of the gap between the first planar coil 416 and the second planar coil 418 is greater than the sum of the width of the conductive path 420 and the width of the recess or dam 460. The groove 460 can be formed using various known grooving methods. The retaining wall 460 may be integrally formed on the PCB board without any connection gap with the PCB board. The grooves 460 or the retaining walls 460 on both sides may be symmetrically arranged and the same with respect to the conductive path, thereby realizing the isolation of the conductive path 420 and the coil for measurement, and thus helping to further reduce the interference and increase the creepage distance between the coil and the measured lead. In some examples, the retaining wall 460 may also advantageously increase the electrical gap between the coil and the wire being tested.

Fig. 5 shows a schematic diagram of a power transfer switch 50 according to an embodiment of the invention. The current measuring device 100 in fig. 5 is the same as the current measuring devices 100, 200, 300 in fig. 1A and 1B, fig. 2A and 2B, and fig. 3, and thus, the description thereof is omitted.

The power transfer switch 50 includes a current measuring device 100, a switching device 200, and a control circuit 300.

The switching device 200 has a control pole for controlling the switching device to be turned on and off, a first pole connected to the electromagnet drive mechanism 400, and a second pole electrically connected to the conductive path 120 (not shown in fig. 5) of the current measuring apparatus 100. For example, the switching device may be various power switching devices, such as an insulated gate bipolar transistor IGBT, a metal-oxide semiconductor field effect transistor MOSFET, or other high power switching devices. For example, the control electrode may be a gate or gate electrode of a power switching device. Also, the first pole of the switching device 200 may be a gate electrode, and the second pole may be a drain electrode. Alternatively, the first pole of the switching device 200 may also be the drain and the second pole may be the gate. Also, the control electrode controls the current of the electromagnetic driving mechanism 400 by the PWM control signal, and the electromagnetic driving mechanism 400 may increase or decrease with time. In order to make the current of the electromagnetic drive mechanism 400 relatively stable, the current measurement device 100 measures the current I (t) associated with the time-varying current of the electromagnetic drive mechanism 400 at the second pole and generates an induced voltage signal for subsequent adjustment of the PWM control signal, such as changing the pulse width, duty cycle, etc. of the PWM control signal.

In some examples, an input of control circuit 300 is connected to an output of the electromagnetic induction of current measurement apparatus 100 and an output of control circuit 300 is connected to a control pole of switching device 200 to maintain current flow through the electromagnet drive circuit. For example, the output end of the electromagnetic induction of the current measuring apparatus 100 performs a signal processing process such as integration and amplification on the induced voltage signal u (t), and finally the PWM control signal associated with the current I (t) can be obtained based on the integrated and amplified induced voltage signal u (t) via the control circuit 300. Thus, the PWM signal is a rectangular signal, which can make the current of the electromagnetic driving mechanism 400 pull down the current value when the current value is larger than the threshold value to effectively protect the switching device 200 and to stabilize the current of the electromagnetic driving mechanism 400. Therefore, the power supply changeover switch 50 having the current measuring device 100 and the control circuit 400 can realize closed-loop control of the current of the electromagnetic drive mechanism 400.

The power transfer switch 50 with current measurement device is merely exemplary, and the current measurement device of the present invention can also be applied to other electrical applications as long as the application requires accurate measurement of the time-varying current. But also can eliminate or reduce the interference influence of interference current, electromagnetism and the like on the current measuring device.

The hardware configurations described herein, such as processors, control systems, control circuits, etc., may be implemented by various suitable hardware means, including but not limited to, FPGAs, ASICs, socs, discrete gate or transistor logic, discrete hardware components, or any combinations thereof.

The block diagrams of circuits, devices, apparatus, devices, and systems presented herein are meant to be illustrative examples only and are not intended to require or imply that the blocks, devices, and systems shown in the block diagrams must be connected or arranged or configured in a manner consistent with the teachings of the block diagrams. As will be appreciated by one skilled in the art, these circuits, devices, apparatus, devices, systems may be connected, arranged, configured in any manner that achieves the intended purposes.

It should be understood by those skilled in the art that the foregoing specific embodiments are merely exemplary and not limiting, and that various modifications, combinations, sub-combinations and substitutions may be made in the embodiments of the invention depending upon design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.

Claims (8)

1. A current measuring device is characterized in that,

the current measuring device comprises at least one printed circuit board layer and a conductive path carrying a current to be measured;

each of the at least one printed circuit board layer comprises a first circuit board portion having a first planar coil disposed thereon and a second circuit board portion having a second planar coil disposed thereon;

the conductive path is disposed between the first planar coil and the second planar coil; and is

All of the first planar coils and the second planar coils of the at least one printed circuit board layer are electrically connected for electromagnetically inducing a current in the conductive path.

2. The current measurement device of claim 1, further comprising:

a printed circuit board top layer located above the at least one printed circuit board layer and comprising a first surface metal shield area; and

a printed circuit board bottom layer located below the at least one printed circuit board layer and including a second surface metal shielding area;

the first surface metal shielding region and the second surface metal shielding region cover the first planar coil, the second planar coil, and the conductive path.

3. Current measuring device according to claim 1,

the first planar coil and the second planar coil are connected in series and wound in opposite directions, respectively.

4. Current measuring device according to claim 1,

the first planar coil and the second planar coil have a predetermined number of winding turns.

5. Current measurement device according to claim 4,

the number of layers of the at least one printed circuit board layer is 2N, where N is an integer greater than 1, and the number of winding turns is greater than or equal to 6.

6. Current measuring device according to claim 2,

and copper is paved on the first surface metal shielding region and the second surface metal shielding region.

7. Current measuring device according to claim 1,

and a groove or a retaining wall is arranged between the conductive path and the first planar coil and the second planar coil which are positioned at two sides of the conductive path.

8. A power transfer switch, comprising:

the current measurement device of claims 1-7;

a switching device having a control pole for controlling the switching device to be turned on and off, a first pole connected to the electromagnet driving mechanism, and a second pole electrically connected to the conductive path of the current measuring device; and

a control circuit having an input connected to the output of the electromagnetic induction of the current measuring device and an output connected to the control electrode of the switching device to maintain the current flowing through the electromagnet drive circuit.

Images