• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    System and method for detecting faults to ground or against the chassis in DC systems with inverters powered by batteries. A ground fault detection system is disclosed in DC systems with inverters powered by batteries. The system comprises: an average voltage point (9) of the battery (1); an impedance (6) between the point of medium tension (9) and earth or chassis (7); a measuring device (8) of the current/voltage in the impedance, obtaining a measured signal (22); an analyzer device (10) of the signal. The analyzer device comprises: means of harmonic decomposition (11) of the signal; means for obtaining the amplitude and polarity of the direct current signal (12) and the amplitude of said signal in alternating current (13); comparison means in continuous (14) and in alternate (16) in charge of comparing said amplitude in current with a predetermined value of continuous AFAULT cc (15) and of alterna AFAULT CA (17), and obtain output signals (19 to 21) indicative of the existence or absence of ground fault. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2716482A1
    申请号:ES201831236
    申请日:2018-12-18
    公开日:2019-06-12
    发明作者:Gaona Carlos Antonio Platero
    申请人:Universidad Politecnica de Madrid；
    IPC主号:
    专利说明:

    [0001]
    [0002]
    [0003]
    [0004] OBJECT OF THE INVENTION
    [0005] The present invention is applicable to electrical systems in which inverters are involved, powered from batteries.
    [0006] A clear application are electric vehicles, in which traction motors are powered by inverters from batteries.
    [0007] With the system object of the present invention, short circuits to earth or to the chassis of the vehicle can be detected, both in the direct current zone and in the alternating current zone without the need of any additional source of current or voltage injection and it can be distinguished in which zone the defect has occurred, zone of direct current or zone of alternating current.
    [0008]
    [0009] BACKGROUND OF THE INVENTION
    [0010] All electrical installation must be equipped with protection systems that make it safe against possible short circuits and other defects that may cause damage to both the facilities and people.
    [0011] In the case of electric vehicles, it is common practice that the entire electrical system is isolated from the vehicle's chassis or ground. If a defect occurs to the chassis of the vehicle or to ground can continue to work. But an alarm must be generated to repair this defect and avoid having a double defect and that the system stops working.
    [0012] Therefore, it would be desirable to be able to detect faults in the DC system with inverters supplied by batteries and, more specifically, to differentiate whether the defect is on the DC side or on the AC side. Additionally, it would be desirable to know if, when the defect occurred on the DC side, the defect has occurred at some point of the positive or negative circuit.
    [0013] DESCRIPTION OF THE INVENTION
    [0014] The invention relates to a system for detecting ground or chassis faults in DC systems with inverters powered by batteries.
    [0015] In a first aspect of the invention, a ground fault detection system is disclosed in DC systems with inverters powered by batteries, where said DC systems comprise at least one battery, DC bars and a plurality of inverters that feed a plurality of charges in alternating current. The ground fault detection system in DC systems with inverters powered by batteries comprises:
    [0016]
    [0017] • a point of medium voltage of the battery where half of the battery voltage is obtained;
    [0018]
    [0019] • a grounding impedance between the average voltage point of the battery and the ground or chassis of a vehicle;
    [0020]
    [0021] • a device for measuring the current / voltage in the grounding impedance, obtaining a measured signal;
    [0022]
    [0023] • an analyzer device responsible for analyzing the signal measured and comprising:
    [0024] - means of harmonic decomposition of the measured signal;
    [0025] - means for obtaining the amplitude and polarity of the signal measured in direct current;
    [0026] - means for obtaining the amplitude of the signal measured in alternating current; - continuous comparison means responsible for comparing said amplitude in direct current with a predetermined value AFALLo cc, and obtaining two output signals indicative of the existence or absence of ground fault of a DC part of the DC system with powered inverters by batteries;
    [0027] - alternating comparison means in charge of comparing the amplitude of the alternating current measured signal with a predetermined value Afallo CA, and obtaining at least one output signal indicative of the existence or absence of ground fault of an alternating part of the system of direct current with inverters powered by batteries.
    [0028] At this point it must be remembered that the DC part of the DC system with inverters powered by batteries consists of the battery, the DC bars and the DC part of the inverters. While the alternating part of the DC system with inverters powered by batteries is formed by the alternating part of the inverters and the loads connected to them.
    [0029] In an embodiment of the invention, the DC comparison means additionally comprise means for analyzing the polarity, which generate signals that indicate whether the ground fault has occurred in the positive or in the negative.
    [0030] In another embodiment of the invention, the system additionally comprises a voltage divider so that a voltage equivalent to the middle point of the battery is obtained at a medium voltage point of the voltage divider. The grounding impedance is connected between the midpoint of the voltage divider and ground or chassis of the vehicle.
    [0031] In another embodiment of the invention, the means of obtaining the amplitude of the measured signal comprise:
    [0032] - means for calculating the Fourier transform in order to obtain the spectrum of the measured signal, and
    [0033] - filter media at zero frequency and operating frequency of the inverters.
    [0034] In a second aspect of the invention, a method of detecting ground faults in DC systems with inverters powered by batteries is disclosed, wherein said DC systems comprise a battery, DC bars and a plurality of inverters that they feed a plurality of charges in alternating current. The method comprises the following steps:
    [0035] a) reference to earth the midpoint of the battery by means of a grounding impedance connected between the midpoint of the battery and earth / chassis; b) measure the current / voltage in the grounding impedance, obtaining a measured signal;
    [0036] c) Analyze the measured signal by carrying out the following sub-steps:
    [0037] i) decompose the measured signal into harmonics;
    [0038] ii) obtain the amplitude and polarity of the signal measured in direct current; iii) obtain the amplitude of the signal measured in alternating current; iv) comparing said amplitude in direct current with a predetermined value AFALLo cc, and obtaining two output signals indicative of the existence or not of ground fault / chassis and, in case it has produced, analyze the polarity, and generate signals that indicate if it has been produced in the positive or negative part of a continuous DC system with inverters powered by batteries; v) compare the amplitude of the signal measured in alternating current with a predetermined value AFallo ca, and obtain at least one output signal indicative of the existence or lack of ground fault of an alternating part of the DC system with powered inverters by batteries.
    [0039] In an embodiment of the invention, step a) additionally comprises applying a voltage divider so that a potential equivalent to the midpoint of the battery is obtained at its midpoint.
    [0040]
    [0041] BRIEF DESCRIPTION OF THE FIGURES
    [0042] To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, an assembly of drawings is included as an integral part of said description, in which the illustrative and non-limiting character has been represented. following:
    [0043] Figure 1 shows a scheme of the system in which the present invention has application where a battery with accessible middle point has been represented.
    [0044] Figure 2 shows a scheme of the system in which the present invention has application where a battery with no accessible middle point and a voltage divider has been represented.
    [0045]
    [0046] PREFERRED EMBODIMENT OF THE INVENTION
    [0047] The present invention allows detecting earth faults to the chassis in DC systems with inverters powered by batteries. The method has the advantage that it does not need any additional source and allows distinguishing the faults that occur both in the continuous stage and in the alternate stage, and even detects and identifies if the defect is any of the positive or negative conductors. of the continuous stage.
    [0048] The references used in the figures are the following:
    [0049] 1, the battery.
    [0050] 2, DC bars.
    [0051] 3, an investor.
    [0052] 4, a load in alternating current.
    [0053] 5, voltage divider.
    [0054] 6, impedance grounding or connection to the chassis.
    [0055] 7, ground point or chassis.
    [0056] 8, measuring equipment of the current or voltage in the grounding impedance.
    [0057] 9, middle point of the battery.
    [0058] 10, current or voltage analyzer device in the grounding impedance.
    [0059] 11, means of harmonic decomposition of the signal.
    [0060] 12, means for obtaining the amplitude and polarity of the current or voltage in the impedance of grounding, in direct current.
    [0061] 13, means for obtaining the amplitude and polarity of the current or voltage in the grounding impedance, in alternating current.
    [0062] 14, amplitude comparator device.
    [0063] 15, determined value AFAllo cc, from which it is determined that there is a fault in the DC part.
    [0064] 16, amplitude comparator device.
    [0065] 17, value determined AFAllo cA, from which it is determined that there is a fault in the part of alternating current.
    [0066] 18, analyzer of the polarity of the DC component of the current or voltage signal in the grounding impedance.
    [0067] 19, signal missing to ground on the positive side of the continuous system.
    [0068] 20, signal is missing to ground on the negative side of the continuous side of the system.
    [0069] 21, signal missing to ground on the alternate side of the system.
    [0070] 22, measured signal of the current or voltage in the grounding impedance. Figures 1 and 2 show inverters 3 powered by at least one battery 1 from which the DC busses 2 are fed. The inverters 3 convert the direct current into alternating current of adjustable frequency, for the supply of charges in alternating current 4. Depending on whether the midpoint 9 of battery 1 is accessible or not, we have two embodiments. The midpoint 9 of the battery 1 for the present invention is that point at which a voltage whose value is half the value of the nominal voltage of the battery is obtained. That is, if a battery has 12V of nominal voltage, at the midpoint you would get 6V voltage if measured between this midpoint and either of the two terminals of the battery.
    [0071] The earth fault detection system or the chassis in DC systems with inverters supplied by batteries of the present invention is based on the measurement of the current / voltage in a high ohmic value impedance 6 installed between the midpoint of the battery and earth / chassis (see figures). It is for this reason that before describing the embodiments, the relationship between the defects and the current / voltage measurements in the impedance will be described. It is to be considered that the inverter 3 or inverters are fed through busbars 2 as shown in Figure 1. In this case it has been considered that the midpoint 9 of the battery 1 is accessible. Between the midpoint 9 and ground or chassis, in the case of an electric vehicle, a grounding impedance is connected 6. The measurement of the current through the grounding impedance 6 upon occurrence of a ground fault in the system will be of the following nature:
    [0072]
    [0073] • Ground fault in the alternating stage: a current of greater or lesser amplitude is produced, depending on the impedance of the fault, with a frequency component equal to the frequency of the inverter 3 that feeds the fault.
    [0074]
    [0075] • Fault to ground in the positive of the continuous stage: a direct current (or null frequency) of greater or lesser amplitude is produced, depending on the impedance of the fault and which causes the middle point of the battery to have a potential lower than the ground or chassis.
    [0076]
    [0077] • Ground fault in the negative of the DC stage: a direct current (or null frequency) of greater or lesser amplitude is produced, depending on the impedance of the fault and which causes the midpoint of the battery to have a potential superior to the ground or chassis.
    [0078]
    [0079] • Simultaneous failure in the alternating and continuous stages: a current with harmonic content of the inverter and continuous frequency is produced.
    [0080] Instead of measuring the current by the grounding impedance, alternatively the voltage in the impedance can be measured, the method being analogous.
    [0081] The first embodiment shown in Figure 1 represents the system of the present invention when the middle point of the battery is accessible. On the other hand, Figure 2 represents the system of the present invention when the midpoint of the battery is not accessible. The only difference between the system shown in Figure 1 and the shown in Figure 2, is that the system shown in Figure 2 additionally comprises the voltage divider 5.
    [0082] Therefore, the system for detecting ground faults or the chassis in direct current systems with inverters supplied by batteries of the present invention comprises:
    [0083] - the grounding impedance / chassis 6 which is connected on the one side to ground / chassis 7 and on the other hand to the midpoint of the battery 9, if accessible. In the event that the midpoint of the battery 9 is not accessible, a voltage divider 5 is connected to the battery 1 so that a voltage equivalent to the midpoint of the battery 9 is obtained at the midpoint of the divider 5 for this purpose. two equal impedances can be used in the configuration shown in figure 2.
    [0084] - the measuring device 8 of the current flowing through the grounding impedance 6, or of the voltage existing therein, obtaining the measured signal 22;
    [0085] - the analyzer device 10 responsible for analyzing the measured signal 22 and comprising:
    [0086]
    [0087] • means for harmonic decomposition 11 of the measured signal 22;
    [0088]
    [0089] • means for obtaining the amplitude and polarity of the measured signal 22 in direct current 12;
    [0090]
    [0091] • means for obtaining the amplitude of said measured signal 22 in alternating current 13 at the operating frequency of the inverters 3;
    [0092] • the comparison means 14 responsible for comparing said amplitude in direct current with a predetermined value AF allo cc 15, and obtaining at least one output signal indicative of the existence or not of ground fault / chassis and, in case has produced, the polarity analysis means 18, which generates signals that indicate whether it has occurred in positive 19 or in negative 20 of the electrical system (that is, of the DC system with inverters powered by batteries) in function of the polarity of the signal.
    [0093]
    [0094] • the comparison means 16 responsible for comparing said amplitude in alternating current with a determined value AFAllo cA 17, and obtaining at least one output signal 21 indicative of the existence or not of a ground fault on the alternate side of the electrical system ( that is, the current system continues with inverters powered by batteries).
    [0095] The harmonic decomposition means 11 of the measured signal of the analyzer device preferably comprises:
    [0096] - the means for calculating the Fourier transform 11 responsible for obtaining the spectrum of the measured signal, and
    [0097] - the filtering means 12-13 at the zero frequency and the frequency of the inverters 3 of the signal resulting from said means.
    [0098] Another object of the present invention is a method of detecting ground faults in systems with inverters powered by batteries, comprising:
    [0099] - reference to earth, through a ground / chassis impedance, the midpoint of the battery;
    [0100] - measure the current flowing through the ground / chassis impedance, obtaining a measured signal;
    [0101] - obtain the amplitude of said signal measured at zero frequency and at the frequency of the inverters;
    [0102] - obtain the polarity of said signal measured at zero frequency;
    [0103] - compare said amplitudes to the frequency zero and the frequency of the inverters with a predetermined values AFALLo cc and AFall ac, and obtain at least two output signals that indicate whether the defect in the part of direct current or in the current part alternate;
    [0104] - compare the polarity of the signal to the zero frequency, and obtain at least two output signals that indicate whether the defect is in the positive or negative of the DC system.
    [0105] The step of obtaining the amplitude of the signal measured at zero frequency and the frequency of the converters can comprise in turn:
    [0106] - calculate the Fourier transform to obtain the spectrum of the measured signal, and - filter said resulting signal at the frequency and frequency of the converters.
    权利要求:
    Claims (7)
    [1]
    1. System for detecting ground faults in DC systems with inverters powered by batteries, where said DC systems comprise at least one battery (1), DC bars (2) and a plurality of inverters ( 3) that feed a plurality of loads in alternating current (4); The system is characterized in that it comprises:
    • a half point of the battery (9) where half of the battery voltage (1) is obtained;
    • a grounding impedance (6) between the midpoint of the battery (9) and earth (7);
    • a measuring device (8) of the current / voltage in the grounding impedance (6), obtaining a measured signal (22);
    • an analyzer device (10) responsible for analyzing the measured signal (22) and comprising:
    - harmonic decomposition means (11) of the measured signal (22);
    - means for obtaining the amplitude and polarity of the measured signal (22) in direct current (12);
    - means for obtaining the amplitude of the measured signal (22) in alternating current (13);
    - continuous comparison means (14) in charge of comparing said amplitude in direct current with a predetermined value A FAllo cc (15), and obtaining two indicative output signals (19-20) of the existence or absence of ground fault of the DC part of the DC system with inverters powered by batteries;
    - alternating comparison means (16) in charge of comparing the amplitude of the measured signal (22) in alternating current with a predetermined value A FAllo cA (17), and obtaining at least one output signal (21) indicative of the existence or no earth fault of the AC part of the DC system with inverters powered by batteries.
    [2]
    2. - System for detecting ground faults in DC systems with inverters powered by batteries, according to claim 1, wherein the means of continuous comparison (14) additionally comprise means for analyzing the polarity (18), which they generate signals that indicate if the ground fault has occurred in the positive (19) or in the negative (20).
    [3]
    3. - System for detecting ground faults in DC systems with inverters powered by batteries, according to claim 1 or 2, wherein the system additionally comprises a voltage divider (5) so that it is obtained at the midpoint of said voltage divider, a voltage equivalent to the midpoint of the battery; and where the grounding impedance (6) is connected between the medium voltage point of the voltage divider (5) and earth (7).
    [4]
    4. - System for detecting ground faults in DC systems with inverters powered by batteries, according to any one of the preceding claims, wherein the means for obtaining the amplitude of the measured signal (22) comprise:
    - means for calculating the Fourier transform (11) responsible for obtaining the spectrum of the measured signal (22), and
    - filtering means (12,13) at the zero frequency and operating frequency of the inverters (3).
    [5]
    5. - Ground fault detection system in DC systems with inverters powered by batteries, according to any one of the preceding claims, wherein the earth (7) is made on a chassis of a vehicle.
    [6]
    6. - Method of detection of ground faults in DC systems with inverters powered by batteries, where said DC systems comprise a battery (1), DC bars (2) and a plurality of inverters (3) which feed a plurality of charges in alternating current (4), characterized in that it comprises:
    d) reference to ground the midpoint (9) of the battery (1) by means of a grounding impedance (6) connected between the middle point of the battery (9) and earth / chassis (7);
    e) measuring the current / voltage in the grounding impedance (6), obtaining a measured signal (22);
    f) analyze the measured signal (22) carrying out the following sub-steps:
    i) decompose the measured signal into harmonics (22);
    ii) obtaining the amplitude and polarity of the measured signal (22) in direct current (12);
    iii) obtaining the amplitude of the measured signal (22) in alternating current (13);
    iv) comparing said amplitude in direct current with a predetermined value A cc Failure (15), and obtaining two indicative output signals (19-20) of the existence or absence of earth fault / chassis and, in case it has produced, analyze the polarity (18), and generate signals that indicate if it has occurred in the positive (19) or negative (20) of the DC part of the DC system with inverters powered by batteries;
    v) comparing the amplitude of the measured signal (22) in alternating current with a predetermined value A FAllo cA (17), and obtaining at least one output signal (21) indicative of the existence or not of ground fault of the part in alternating DC system with inverters powered by batteries.
    [7]
    7. Method for detecting ground faults in DC systems with inverters powered by batteries, according to claim 6, wherein step a) additionally comprises applying a voltage divider (5) so that it is obtained at its midpoint a potential equivalent to the midpoint of the battery (1).

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    引用文献:
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    US20040212371A1|2003-04-28|2004-10-28|Yoshikazu Nomoto|Ground fault detection device|
    US20070176604A1|2006-01-30|2007-08-02|Naohisa Morimoto|Ground-fault resistance measurement circuit and ground-fault detection circuit|
    US20160245853A1|2015-02-19|2016-08-25|Nec Energy Solutions, Inc.|Systems and methods of detecting ground faults in energy storage and/or generation systems that employ dc/ac power conversion systems|
    US20170294791A1|2016-04-07|2017-10-12|Toyota Jidosha Kabushiki Kaisha|Electric vehicle|
    法律状态:
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    ES201831236A|ES2716482B2|2018-12-18|2018-12-18|SYSTEM AND METHOD OF DETECTION OF FAULTS TO GROUND OR AGAINST THE CHASSIS IN DIRECT CURRENT SYSTEMS WITH INVERTERS POWERED FROM BATTERIES|ES201831236A| ES2716482B2|2018-12-18|2018-12-18|SYSTEM AND METHOD OF DETECTION OF FAULTS TO GROUND OR AGAINST THE CHASSIS IN DIRECT CURRENT SYSTEMS WITH INVERTERS POWERED FROM BATTERIES|
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