CN-122029943-A - Residual current monitor

Abstract

Power distribution systems and methods are disclosed in which a Power Distribution Unit (PDU) includes a Residual Current Monitor (RCM) to detect the presence of downstream leakage current in the PDU. The RCM may include a current sensor having a core through which a power conductor passes and a winding surrounding the core. The driving circuit of the RCM generates alternating driving signals through the driving windings to drive the core into and out of positive and negative saturation. The sensing circuit of the RCM generates a response signal that is filtered by a high order current signal filter to isolate the downstream leakage current characteristics.

Inventors

• SVEN ANDERSON
• William Harold Avery
• Thomas. Xue
• Thomas Raul
• ALEX LEE
• Stefan Oberzer
• Michael. Shu Qiaofu

Assignees

• 罗格朗数据电源及控制有限责任公司

Dates

Publication Date

20260512

Application Date

20240911

Priority Date

20230913

Claims (16)

1. 1. A Power Distribution Unit (PDU), comprising: an elongated housing; a power input associated with the elongated housing, the power input comprising a plurality of power conductors; a plurality of power outputs electrically connected to the power inputs for powering the electrical devices, and A Residual Current Monitor (RCM) associated with the power supply input for detecting the presence of a downstream leakage current, the residual current monitor comprising: a sensor, comprising: a magnetizable core, at least some of the plurality of power supply conductors intersecting the core; A plurality of drive windings surrounding the core; A drive circuit operable to generate an alternating drive signal through the plurality of drive windings sufficient to drive the core into and out of positive and negative saturation; A sense circuit responsive to the downstream leakage current on the plurality of power supply conductors corresponding to the leakage current to bias at least one of the alternating drive signals and generate a response signal, and A high order current signal filter for removing high frequency components of the response signal to isolate characteristics of the downstream leakage current.
2. 2. The power distribution unit of claim 1, wherein the core is a toroidal ferromagnetic core, and wherein the plurality of drive windings includes a first drive winding wound around a circumference of the toroidal ferromagnetic core, and a second drive winding wound around the circumference of the toroidal ferromagnetic core such that a magnetic flux generated by the first drive winding is opposite a magnetic flux generated by the second drive winding.
3. 3. The power distribution unit of claim 2, wherein each of the plurality of drive windings is wound around the toroidal ferromagnetic core circumference with a selected number of turns.
4. 4. The power distribution unit of claim 2, wherein the power distribution unit includes a test circuit in combination with a third winding.
5. 5. The power distribution unit of claim 1, wherein the power input is a multi-phase input configured as a delta input or a star input.
6. 6. The power distribution unit of claim 1, wherein the power input comprises two phase conductors or one phase conductor and one neutral conductor.
7. 7. The power distribution unit of claim 1, wherein the higher order current signal filter is at least a 3-order filter, including an RC filter.
8. 8. The power distribution unit of claim 1, wherein the higher order current signal filter is at least a 3-order filter, including a SINC filter.
9. 9. The power distribution unit of claim 1, wherein the higher order current signal filter is at least a 3-order filter, including a low pass filter.
10. 10. The power distribution unit of claim 1, wherein the drive circuit comprises a timing circuit for controlling the alternating drive signal.
11. 11. A Power Distribution Unit (PDU), comprising: A housing; at least one power input associated with the housing, the at least one power input comprising a plurality of power conductors; a plurality of power outputs electrically connected to the at least one power input for powering the electrical device, and A Residual Current Monitor (RCM) associated with the at least one power supply input for detecting the presence of a downstream leakage current, the residual current monitor comprising: a sensor, comprising: a magnetizable core, at least some of the plurality of power supply conductors intersecting the core; A plurality of drive windings surrounding the core; A drive circuit operable to generate an alternating drive signal through the plurality of drive windings sufficient to drive the core into and out of positive and negative saturation; A sense circuit responsive to the downstream leakage current on the plurality of power supply conductors corresponding to the leakage current to bias at least one of the alternating drive signals and generate a response signal, and A high order current signal filter for removing high frequency components of the response signal to isolate characteristics of the downstream leakage current.
12. 12. A Power Distribution Unit (PDU), comprising: A housing; A power input comprising a plurality of power conductors for powering components within the power distribution unit; A plurality of outputs for powering the electrical devices, and A Residual Current Monitor (RCM) for detecting the presence of a leakage current, the residual current monitor comprising: A sensor responsive to the leakage current to generate a response signal representative of the leakage current, and A filter operable to isolate characteristics of the leakage current from the response signal.
13. 13. The power distribution unit of claim 12, wherein the response signal has a 50/50 duty cycle in the absence of the leakage current and a non-50/50 duty cycle or amplitude change in the presence of the leakage current.
14. 14. The power distribution unit of claim 12, wherein the sensor includes an annular ferromagnetic core surrounding at least some of the plurality of power conductors and at least one pair of drive windings that generate oppositely directed magnetic flux around the annular ferromagnetic core, wherein the presence of the leakage current corresponds to a net current on the power conductors passing through the annular ferromagnetic core, the response signal being induced on the drive windings, wherein the presence of the leakage current affects a duty cycle of the response signal.
15. 15. The power distribution unit of claim 12, wherein the filter is a high order filter operable to remove high frequency components from the response signal, wherein the high order filter is at least a 3-order filter comprising an RC filter, a SINC filter, and a low pass filter.
16. 16. A residual current monitor, comprising: a sensor, comprising: A magnetizable core; a first drive winding surrounding the core; A second drive winding surrounding the core; A plurality of power conductors intersecting the core, the plurality of power conductors being associated with a system under test; a drive circuit operable to generate drive signals through the first and second drive windings sufficient to alternately drive the core into and out of positive and negative saturation, wherein the presence of leakage current in the system under test biases at least one of the drive signals and generates a response signal, and A high order filter for removing a high frequency component of the response signal to isolate the characteristics of the leakage current.

Description

Residual current monitor Cross Reference to Related Applications The present application claims priority from U.S. patent application Ser. No. 18/466,531, filed on 9/13 of 2023, the entire disclosure of which is incorporated herein by reference. Technical Field The present disclosure relates generally to power distribution units, and more particularly, to power distribution units that provide methods and systems for detecting leakage current. Background A conventional Power Distribution Unit (PDU) is an electrical outlet (also referred to as a receptacle) assembly that receives power from a power source and distributes the power to one or more individual electronic devices. Each such PDU assembly has a power input that receives power from one or more power sources over the PDU's power line. The electrical outlet may be used to power one or more electronic devices plugged into the PDU outlet. PDUs are used in many applications and environments, for example, in or on an electronic equipment rack. Leakage current in the PDU constitutes a safety hazard to personnel. Leakage currents, particularly in high voltage environments, may cause personnel to get shocked, fire and/or equipment to fail. Due to the risk of leakage currents, many countries now require residual current monitoring to detect leakage currents and to issue alarms to protect personnel and equipment. Drawings The nature and advantages of the present technology may be further understood by reference to the following drawings. In the drawings, similar components or features may have the same reference numerals. Fig. 1 is a diagram of an example Power Distribution Unit (PDU). Fig. 2 is a partial block diagram wiring diagram of the PDU of fig. 1 connected to a power supply input and a network. Fig. 3 shows a diagram of a Residual Current Monitor (RCM) circuit including a residual current sensor and a demodulator. Fig. 4A shows a schematic circuit diagram of a residual current sensor for detecting leakage current in a PDU. Fig. 4B shows a diagram of an RCM circuit including a residual current sensor, an RC filter, an ADC, and a chebyshev (Chebychev) low pass filter. Fig. 5A shows a representative sensed voltage response signal based on the presence or absence of leakage current. Fig. 5B shows a representative voltage waveform depicting no leakage current in a PDU. Fig. 5C shows a representative voltage waveform depicting the presence of positive leakage current in a PDU. Fig. 5D shows a representative voltage waveform depicting the presence of negative leakage current in a PDU. Fig. 6 shows a diagram of an RCM circuit depicting a more detailed representation of a demodulator. Fig. 7 shows an example of a filtered residual current signal after passing through an RC low pass filter. Fig. 8 shows an example of a filtered residual current signal after passing through a SINC filter. Fig. 9 shows an example of a filtered residual current signal after passing through a chebyshev low pass filter. Fig. 10 shows an example of a filtered residual current signal after passing through an RC filter followed by a chebyshev low pass filter. Fig. 11 shows an example of a filtered residual current signal after passing through an RC filter followed by a SINC filter and a chebyshev low pass filter. Fig. 12A is a block diagram of one embodiment of a jack module for use in the PDU of fig. 1. Fig. 12B is a block diagram of another embodiment of a receptacle module for use in the PDU of fig. 1. Detailed Description The description provides examples and is not intended to unnecessarily limit the scope, applicability, or configuration of the invention. Rather, the following description will enable any person skilled in the art to practice embodiments of the invention. Various changes may be made in the function and arrangement of elements. Accordingly, various embodiments may omit, replace, and/or add various procedures or components as appropriate. For example, aspects and elements described with respect to certain embodiments may be combined in various other embodiments. It should also be appreciated that the following systems, devices, and components may be components of a larger system, individually or collectively, wherein other processes may take precedence over or otherwise modify their application. Embodiments of the disclosed technology relate to a Power Distribution Unit (PDU) that has the ability to detect the presence of downstream leakage/residual current, such as leakage current associated with components connected to the PDU, or within the PDU itself. The PDU may include a Residual Current Monitor (RCM) to detect the presence of such downstream leakage current. The power conductors from the input power line of the PDU may pass through the center of a core (e.g., a ring ferromagnetic core that is susceptible to magnetization) associated with the RCM. The core may include a pair of drive windings wound around the core circumference such that the magnetic flux genera