System for checking electrical insulation in a converter of an electric vehicle

Abstract

The present invention relates to a system (S) for checking the electrical insulation of a converter of an electric vehicle, the system (S) comprising at least one voltage generator (G, G1, G2) and at least one current detection unit (U, U1, U2), the voltage generator (G, G1, G2) being connected to at least one line (L1-Ln) to be monitored of a high-voltage converter (CNV) of the electric vehicle and to the ground terminal (C) of the converter (CNV), the current detection unit (U, U1, U2) being operatively connected to the voltage generator (G, G1, G2) and configured to detect any current that may be present on the voltage generator (G, G1, G2) and configured to generate at least one warning signal in the event that a current is detected.

Description

Technical Field

[0001] The present invention relates to a system for checking the electrical insulation of a converter for an electric vehicle. Background Art

[0002] Particularly with reference to the field of motor vehicles, it is known to use power electrical equipment generally integrated inside an electric vehicle, such as a battery charger or a DC / DC converter.

[0003] These devices can be connected at the input end to a high-voltage AC power line, are provided with one or more AC / DC and DC / DC converters, and are connected at the output end to the battery or other devices of the electric vehicle.

[0004] Generally, these devices are provided with insulation between the AC input end and the DC output end through a suitable transformer.

[0005] In particular, with respect to AC, the absence or reduction of ground insulation or the vehicle body is detected through the standard differential systems legally existing in all power supply networks. With respect to AC, the absence or reduction of ground insulation is generally monitored on a vehicle by complex dedicated systems that are connected to the high-voltage battery of the vehicle.

[0006] However, such devices do not always have dedicated electrical insulation between the AC input end and the DC output end, or in any case, such devices do not always ensure sufficient insulation.

[0007] Therefore, it is considered necessary to monitor the electrical insulation of known devices to signal and intervene in a timely manner in the case of the absence or reduction of insulation. Summary of the Invention

[0008] The main object of the present invention is to design a system for checking the electrical ground insulation of a converter for an electric vehicle, which system allows for the effective detection and reporting of the absence or partial reduction of electrical insulation.

[0009] Another object of the present invention is to design a system for checking the electrical insulation of a converter for an electric vehicle, which system allows for overcoming the above-mentioned drawbacks of the prior art with a simple, reasonable, easy-to-use, effective, and low-cost solution.

[0010] The foregoing object is achieved by the present system for checking the electrical insulation of a converter for an electric vehicle according to claim 1. Brief Description of the Drawings

[0011] Other features and advantages of the present invention will be more apparent according to two preferred but non-exclusive system embodiments for checking the electrical insulation in a converter for an electric vehicle, shown by way of indication in the attached drawings but not limited thereto, wherein:

[0012] Figure 1 Overall block diagram of a first possible embodiment of the system according to the present invention;

[0013] Figure 2 Overall block diagram of a second possible embodiment of the system according to the present invention. Detailed implementation

[0014] Specifically referring to these drawings, the reference letter S globally designates a system for checking electrical insulation, which can be particularly used in the converters of electric vehicles.

[0015] Specifically, the system S can be used on a converter device CNV generally integrated inside an electric vehicle, such as a battery charger or a DC / DC converter.

[0016] Advantageously, the system S includes at least one voltage generator G1, G2, G connected to at least one line L1 - Ln to be monitored of a high - voltage converter CNV of an electric vehicle.

[0017] Furthermore, the voltage generators G1, G2, G are connected to the ground terminal (ground, PE) of the converter CNV.

[0018] The connection of the voltage generators G, G1, G2 to the lines L1 - Ln and to the ground terminal of the converter CNV allows the detection of the absence of electrical insulation of the converter itself between the lines L1 - Ln and the ground.

[0019] In fact, if one or more of the lines L1 - Ln of the converter CNV are not electrically insulated, then the application of the corresponding voltage between the line L1 - Ln and the ground terminal of the converter itself causes the generation of a current. Then, this current can be detected and measured to check for the absence of electrical insulation and to signal it.

[0020] According to a possible embodiment, the voltage generators G, G1, G2 are DC voltage generators.

[0021] Specifically, according to this possible embodiment, the voltage generators G, G1, G2 include DC voltage generators with limited insulation.

[0022] However, different embodiments are not excluded. For example, according to another possible embodiment, the voltage generators G1 to Gn can include square - wave AC voltage generators.

[0023] Conveniently, the current limitation has a dual purpose: to avoid damage to the generator itself and to avoid the circulation of high currents between L1 - Ln and the ground.

[0024] Specifically, referring to Figure 1In the first possible embodiment shown, the converter CNV includes a battery charger provided with a power factor correction unit PFC connected to an external power line AC via an input terminal AC IN, a DC / DC conversion unit connected to the unit PFC, and two output lines L1 and L2 connected to an external load, particularly including a battery B of an electric vehicle.

[0025] Referring to this specific application, the system S includes a plurality of voltage generators G1 and G2, particularly connected to both of the lines L1 and L2 of the converter CNV respectively.

[0026] Furthermore, each of the voltage generators G1 and G2 is connected to the external metal housing C of the converter CNV itself.

[0027] Alternatively, since the housing C is generally connected to the ground terminal of the vehicle, each of the voltage generators G1, G2 can be connected to this ground terminal. On the other hand, referring to Figure 2 In the second possible embodiment shown, the system S includes a single voltage generator G configured to generate a plurality of voltages, provided with a plurality of connections that can be respectively connected to a plurality of lines L1-Ln to be monitored and to the ground terminal.

[0028] According to Figure 2 In the present possible embodiment shown, the voltage generator includes a plurality of voltage generators G1 to Gn connected to the corresponding lines L1-Ln to be monitored.

[0029] According to another possible embodiment, the voltage generator can be connected between the midpoint of the voltage line and the ground terminal. In this way, the presence of current at this midpoint allows the detection of the absence of insulation on other lines as well.

[0030] Advantageously, the system S includes at least one current detection unit U, U1, U2, which is operatively connected to at least one voltage generator G, G1, G2 and configured to:

[0031] -- Detect any current present on the voltage generators G, G1, G2, and

[0032] -- Generate at least one warning signal in the case of detection of such current.

[0033] Particularly, referring to Figure 1 In the embodiment shown, the system includes a plurality of current detection units U1, U2, particularly operatively connected to both of the corresponding voltage generators G and G2.

[0034] In this configuration, each of the detection units U1 and U2 is capable of detecting the possible current generated by the corresponding voltage generators G1 and G2.

[0035] Thus, each of the detection units U1 and U2 is able to emit a signal regarding the absence of electrical insulation of the respective lines L1 and L2.

[0036] On the other hand, referring Figure 2 to the alternative embodiment shown, the system S includes a single current detection unit U, which is operatively connected to a single voltage generator G.

[0037] In this configuration, the current detection unit U is configured to detect the general current.

[0038] Thus, referring to this particular configuration, the current detection unit U is able to detect the absence of general insulation, regardless of the individual specific monitored lines with missing insulation.

[0039] According to a possible embodiment, the detection units U, U1, U2 include at least one ammeter M, which is operatively connected to the voltage generators G, G1, G2.

[0040] Preferably, the ammeter M is an absorption ammeter, which is configured to measure the current absorbed by the voltage generators G, G1, G2.

[0041] Furthermore, the detection units U, U1, U2 include at least one comparison and signaling unit A, which is operatively connected to the ammeter M and is configured to:

[0042] -- compare the current value detected by the ammeter M with at least one predetermined threshold,

[0043] -- send a warning signal in the case where the value of the detected current is greater than the predetermined threshold.

[0044] Conveniently, the threshold is programmable.

[0045] In particular, the comparison and signaling unit A includes a programmable storage unit configured to store the predetermined threshold.

[0046] However, alternative embodiments cannot be excluded, in which the detection units U, U1, U2 measure values different from the current ones but technically equivalent.

[0047] For example, the detection units U, U1, U2 may make voltage measurements or measurements of the resistance values detected between the lines to be monitored.

[0048] Thus, the detection units U, U1, U2 include at least one of the following: an ammeter, a voltmeter, or an ohmmeter.

[0049] Conveniently, as referred to in the first possible embodiment Figure 1As shown, the system S may include corresponding isolation transformers T1 and T2, which are operatively disposed between each voltage generator G1 and G2 and each detection unit U1 and U2.

[0050] In addition, as shown in reference to the second embodiment Figure 2 As shown, the system S includes an isolation transformer T, which is connected to each of the voltage generators G1 to Gn of a general voltage generator G.

[0051] In particular, the use of the isolation transformers T, T1, and T2 is desirable because the system S actually applies voltage between lines L1 - Ln that must be insulated from each other.

[0052] Referring to Figure 1 the first embodiment, the ammeters M of the detection units U1 and U2 may be arranged both upstream and downstream of the corresponding transformers T1 and T2.

[0053] Referring to Figure 2 the second embodiment, the ammeter M of only the general detection unit U must necessarily be placed upstream of the transformer T. The converter CNV is particularly applicable to the field of motor vehicles and includes power electronics installed in electric or hybrid vehicles.

[0054] For example, the converter CNV may include an OBC (on - board charger) battery charger or a DC - DC converter.

[0055] In particular, the converter CNV includes at least one AC IN input terminal connectable to an external power line, at least one DC / DC voltage conversion unit, and at least one output line L1 - Ln connectable to a load B on the electric vehicle.

[0056] Advantageously, the converter CNV includes the system S for checking electrical insulation described above.

[0057] In fact, it has been found that the described invention achieves the intended objectives.

[0058] In particular, it should be emphasized that the system for checking electrical insulation according to the present invention allows for detecting and effectively signaling the absence of electrical insulation in the converter of an electric vehicle.

Claims

1. A system (S) for checking the electrical insulation in a converter of an electric vehicle, characterized in that, The system (S) includes a plurality of voltage generators (G1-Gn, G1, G2) and at least one current detection unit (U, U1, U2). The voltage generators (G1-Gn, G1, G2) are connected to respective lines (L1-Ln) to be monitored of a high-voltage converter (CNV) of an electric vehicle and are connected to a ground terminal (C) of the converter (CNV). The current detection unit (U, U1, U2) is operatively connected to the plurality of voltage generators (G1-Gn, G1, G2) and is configured to detect any current that may be present on the plurality of voltage generators (G1-Gn, G1, G2) and is configured to generate at least one warning signal in the event of detecting the current, and at least one insulation transformer (T1, T2, T) between the plurality of voltage generators (G1-Gn, G1, G2) and the detection unit (U, U1, U2).

2. The system (S) according to claim 1, characterized in that Each of the plurality of voltage generators (G1-Gn, G1, G2) is a DC voltage generator.

3. The system (S) according to claim 2, characterized in that, Each of the plurality of voltage generators (G1-Gn, G1, G2) is an insulated and limited DC voltage generator.

4. The system (S) according to claim 1, characterized in that, Each of the plurality of voltage generators (G1-Gn, G1, G2) is a square-wave AC voltage generator.

5. The system (S) according to claim 1, characterized in that, The detection unit (U, U1, U2) includes at least one of the following: an ammeter (M), a voltmeter, and an ohmmeter.

6. The system (S) according to claim 5, characterized in that, The ammeter (M) is an absorption ammeter configured to measure the current absorbed by the plurality of voltage generators (G1-Gn, G1, G2).

7. The system (S) according to claim 6, characterized in that, The detection unit (U, U1, U2) includes at least one comparison and signaling unit (A). The comparison and signaling unit (A) is operatively connected to the ammeter (M) and is configured to compare the value of the detected current with at least one predetermined threshold. The comparison and signaling unit (A) is configured to send the warning signal when the current value is greater than the threshold.

8. The system (S) according to claim 7, characterized in that, The comparison and signaling unit (A) includes a programmable storage unit configured to store the threshold.

9. A converter (CNV) for an electric vehicle, the converter (CNV) including at least one input terminal, at least one voltage conversion unit (DC / DC), and at least one output line (L1-Ln). The input terminal is connectable to an external power line (L1-Ln), and the output line (L1-Ln) is connectable to a load on the electric vehicle. The converter (CNV) is characterized in that it includes a system (S) for detecting electrical insulation according to one of the preceding claims.

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