Test device for testing a test object, in particular an impedance-bearing test object with complete self-diagnostic capability

Abstract

Testing equipment (1) for testing at least one test object (2) - with an input (3) for applying a test signal, - with an output (4) for tapping a response signal, - with a transformer (5) having a primary (6) and a secondary winding (7), - with at least one first connection contact (8) and with at least one second connection contact (9) for electrically connecting the test device (1) to the at least one test object (2), wherein - the input (3) is connected to a first winding terminal of the primary winding (6), - the output (4) is connected to a second winding terminal of the primary winding (6), - the first terminal contact (8) is electrically connected to a first winding terminal of the secondary winding (7) and - the second terminal contact (9) is electrically connected to a second winding terminal of the secondary winding (7), characterized by the fact that a first switch (10) is connected between the first winding terminal of the secondary winding (7) and the first terminal contact (8) and / or a second switch (11) is connected between the second winding terminal of the secondary winding (7) and the second terminal contact (9), and the test device (1) has a self-diagnostic circuit, wherein the self-diagnostic circuit has a signal input (16), a voltage divider (17) and at least one result transfer point (18), wherein the self-diagnostic circuit has a third switch (19) and / or a fourth switch (20) and at least one signal adaptation, for example an impedance converter (21, 22), and wherein the voltage divider (17) is constructed from resistors (23, 24, 25), preferably three resistors, where - the first resistor (23) is connected between the first and the second switch (10, 11), - the second resistor (24) is connected with a first terminal contact to a first terminal contact of the first resistor (23), - the third resistor (25) is connected with a first terminal contact to a second terminal contact of the first resistor (23).

Description

[0001] The invention relates to an improved test device for testing a test object, in particular an impedance-related test object. The test device has an input for applying a test signal and an output for tapping a response signal, a transformer with a primary and a secondary winding, and at least one first connection contact and one second connection contact for electrically connecting the test device to the test object, wherein the input is connected to a first winding terminal of the primary winding, the output is connected to a second winding terminal of the primary winding, the first connection contact is electrically connected to a first winding terminal of the secondary winding, and the second connection contact is electrically connected to a second winding terminal of the secondary winding.

[0002] Typically, such test equipment is used to examine test objects required, for example, for the operation of electrical energy storage devices. These energy storage devices could be, for instance, the batteries of an electrically powered vehicle, such as an electric vehicle, hybrid vehicle, and / or the like. In principle, various impedance-related (electrically conductive) test objects can be examined. Therefore, the test equipment is also suitable for monitoring stationary test objects.

[0003] A test device for an electrical connection point of an electrical energy storage device of a motor vehicle is known from the prior art (DE 10 2016 007 947 A1).

[0004] The prior art discloses a test device comprising a pulse generator for generating a test signal, which is a voltage pulse, and a transformer having a primary and a secondary winding, wherein the pulse generator is connected to a first winding terminal of the primary winding and a measuring unit is connected to a second winding terminal of the primary winding. At least one winding terminal of the secondary winding is connected to a terminal contact of the electrical connection point, and at least one of the connections has an electrical capacitor between the respective winding terminal of the secondary winding and the terminal contact.

[0005] The current state of the art dictates that the test device is supplied with a voltage pulse via the input for applying a test signal, and a so-called impulse response is recorded via the output for tapping the response signal and evaluated by the measuring unit. This allows the signaling equipment required for the measurement to be galvanically isolated from the electrical connection point.

[0006] This galvanic isolation of the signaling equipment is advantageous when the electrical connection point is part of an electrical system in which high voltages occur, since the test device does not need to be designed for the high voltages due to the galvanic isolation.

[0007] Current technology makes it possible to detect faults at the electrical connection point. These faults can include, for example, impedance changes.

[0008] The inclusion of at least one capacitor is intended to ensure that no parallel branch is formed, which would carry a current flow parallel to the electrical connection point, potentially causing the test device to be subjected to an unacceptably high current. This applies to direct current and must be adapted for alternating current by selecting appropriate components.

[0009] The test device disclosed in the prior art makes it possible to examine the functionality of an electrical connection point of a live component, the test object. However, a real-world setup, for example within a vehicle, consists of numerous components, or test objects, about which a statement needs to be made. In the known prior art, it is not possible to distinguish which component on the secondary side of the transformer has failed, unless a test device is provided for each test object. This would be very complex and therefore very expensive.

[0010] The aforementioned at least one capacitor is intended to allow the electrical connection to be tested even during normal operation without introducing a current flow parallel to the connection. While this capacitor serves to decouple voltage, it provides insufficient protection against voltage spikes that may originate from the electrical connection.

[0011] This is where the invention comes in.

[0012] The object of the present invention is to propose a testing device that eliminates the disadvantages of the prior art and at the same time ensures improved reliability of the proposed testing device.

[0013] The problem is solved by the independent claims and their dependent subclaims.

[0014] In addition to the features mentioned above, a test device according to the invention has a first switch between the first winding terminal of the secondary winding and the first terminal contact and / or a second switch between the second winding terminal of the secondary winding and the second terminal contact.

[0015] The switches are integrated between the winding terminals of the secondary winding and the electrical connection contacts for connecting to the test object.

[0016] The test device has a self-diagnostic circuit, wherein the self-diagnostic circuit has a signal input, a voltage divider and at least one result transfer point.

[0017] The self-diagnostic circuit has a third and / or a fourth switch. These can be changeover switches with a common center terminal and at least two further terminals, for example four further terminals, in particular quadruple analog switches.

[0018] The self-diagnostic circuit features at least one signal adaptation.

[0019] The voltage divider is constructed from resistors, preferably three resistors, wherein the first resistor is connected between the first and the second switch, the second resistor is connected with a first terminal contact to a first terminal contact of the first resistor, and the third resistor is connected with a first terminal contact to a second terminal contact of the first resistor.

[0020] A small current flows through the resistors when the resistance values ​​are high. This results in a predictable voltage level at defined measuring points within the self-diagnostic circuit.

[0021] Advantageously, the switches can be designed as changeover switches with a common center terminal and additional terminals, for example, four further terminals, particularly quadruple analog switches. It is also perfectly conceivable that the switches are not analog. For example, relays could be used.

[0022] The switch with four additional terminals allows a single input signal to control four different outputs of the switch. These outputs are in turn connected to the terminals through which the test objects are accessed.

[0023] This makes it possible to examine four different test objects using a changeover switch with four additional connections.

[0024] By using a larger number of additional connections on the changeover switch, the number of test objects can be increased.

[0025] The test device for testing a test object has a first choke between the first winding terminal of the secondary winding and the first terminal contact and / or a second choke between the second winding terminal of the secondary winding and the second terminal contact.

[0026] The choke ensures that voltage spikes in a high frequency range are suppressed and cannot affect the transformer.

[0027] The test device also has a first protection diode between the first winding terminal of the secondary winding and a ground terminal, and / or a second protection diode between the second winding terminal of the secondary winding and the ground terminal.

[0028] It may be advantageous here to provide that one protective diode blocks in the direction of the first winding terminal of the secondary winding and the other protective diode blocks in the direction of the second winding terminal of the secondary winding.

[0029] The protective diode enables voltage spikes exceeding a permissible voltage to be dissipated with high power via the ground connection. The permissible voltage is determined according to the requirements of the test equipment. If the test equipment according to the invention is located in a vehicle, it may be advantageous for the permissible voltage to be in the range of 10V to 24V.

[0030] Furthermore, it may be provided that a second terminal of the second resistor is connected to the voltage source and / or a second terminal of the third resistor is connected to the ground connection.

[0031] Furthermore, it may be provided that an input of the at least one impedance converter is connected to a second terminal contact of the third and / or fourth multiple analog switch and / or an output of the at least one impedance converter is connected to the measurement result transfer point.

[0032] The signal conditioning unit can include an impedance converter for loadless measurement coupling, split the measurement signal, pre-filter it according to specific requirements, and provide it at the result transfer point. At this point, the signal can be transferred to an evaluation unit, which can be programmed so that the transmitted measurement results are comparable with defined target values.

[0033] If components fail within the testing equipment, the voltage level at the measuring points changes. Consequently, altered measured values ​​are transmitted to the measurement result transfer point. With appropriate programming of the evaluation unit, it may then be possible to locate the faulty component.

[0034] The aim of the self-diagnostic circuit is to monitor the components required for the safe operation of the test equipment in such a way that the proper functioning of the test equipment can be guaranteed.

[0035] It can prove particularly advantageous that the self-diagnostic capability hardly affects the transmission behavior of the testing device.

[0036] The invention is explained in more detail below with reference to the accompanying drawings. These show: Fig. 1 Block diagram for a test device according to the invention Fig. 2 Block diagram of a section of a basic test device according to the invention, assuming that the switches used are quadruple analog switches

[0037] In the figures, identical components are labelled with the same reference symbols.

[0038] In Fig. Figure 1 shows a block diagram of a test device 1 according to the invention.

[0039] The test device 1 has an input 3 as an input for applying a test signal and an output 4 as an output for tapping a response signal, a transformer 5 with a primary 6 and a secondary winding 7, as well as at least one first connection contact 8 and at least one second connection contact 9 for electrically connecting the test device 1 to a test object 2.

[0040] Here, input 3 is connected to a first winding terminal of the primary winding 6, output 4 is connected to a second winding terminal of the primary winding 6, the first terminal 8 is connected to a first winding terminal of the secondary winding 7, and the second terminal 9 is connected to a second winding terminal of the secondary winding 7.

[0041] At least one of the connections, but in the example shown both connections, has an electrical capacitor 30, 31 between the respective winding terminal of the secondary winding 7 and the terminal contact 8, 9. The aforementioned capacitor 30, 31 is intended to achieve decoupling between the test object 2 and the test device 1.

[0042] The test object 1 is an electrical component, such as a contactor or a fuse, whose functionality is to be assessed. In the present embodiment, these are components required for the operation of electrical energy storage devices. Such energy storage devices can be, for example, the batteries of an electrically powered vehicle, such as an electric vehicle, hybrid vehicle, and / or the like.

[0043] It is entirely conceivable that the test device 1 according to the invention could be used to test electrical components 2 that are needed for other technical purposes.

[0044] In the present embodiment, the test device 1 comprises a pulse voltage source 32, which enables the generation or shaping of a voltage pulse intended as a test pulse. The pulse voltage source 32 essentially consists of a driver / amplifier and a filter. The voltage amplitude and pulse power are set by the driver / amplifier. Subsequently, the voltage pulse is bandwidth-limited by the filter to achieve minimal line coupling. Setting the correct pulse width depends on the sensitivity of the filter unit 33.

[0045] In this case, the primary winding 6 of the transformer 5, which is connected to the input 3, is supplied with a voltage pulse by means of the pulse voltage source 32.

[0046] The voltage pulse is transferred to the secondary winding 7 of the transformer 5 by means of the transformer 5 and transmitted via the winding terminals and the connections to the connection contacts 8, 9, to which the test object 2 is connected.

[0047] Depending on the functional state of the test object 2, current flows are established which act back on the primary winding 6 of the transformer 5 via the secondary winding 7.

[0048] This response signal is transmitted via output 4 to the filter unit 33 provided in the present embodiment. From this filter unit 33, the response signal can be provided to an evaluation unit 29.

[0049] To supply power to various components, a DC voltage source 16 is necessary. In the present embodiment, a DC voltage source 16 with an output voltage of 13V...15V DC is used.

[0050] A first switch 10 and a second switch 11 are connected between the first winding terminal of the secondary winding 7 and the first terminal 8 and between the second winding terminal of the secondary winding 7 and the second terminal 9.

[0051] Switches 10 and 11 can be implemented as multiple analog switches with n outputs. For a basic understanding of the test device 1 according to the invention, the case of n=1 is initially considered for the entire circuit. For this initial consideration, the switch is therefore conceptually replaced by a bridge.

[0052] Switches 10 and 11 are supplied via the DC voltage source.

[0053] It is readily conceivable that only one switch 10, 11 is connected between the first winding terminal of the secondary winding 7 and the first terminal 8 or the second winding terminal of the secondary winding 7 and the second terminal 9.

[0054] To protect the test device 1 against voltage spikes, a choke 12, 13 is connected between the first winding terminal of the secondary winding 7 and the first terminal 8, and between the second winding terminal of the secondary winding 7 and the second terminal 9. A protective diode 14, 15 is connected between the first winding terminal of the secondary winding 7 and a ground terminal 26, and between the second winding terminal of the secondary winding 7 and ground terminal 26. In the event of a voltage surge corresponding to the voltage of the protective diodes, the protective diodes 14, 15 become low-resistance, thus preventing the switches 10, 11 from being overloaded. The chokes 12, 13 counteract rapid voltage changes. In this case, the combination of the chokes 12, 13 and the protective diodes 14, 15 provides extensive protection that hardly affects the actual function of the test device 1.

[0055] The test device 1 according to the invention has a self-diagnostic circuit, wherein the self-diagnostic circuit has a voltage source 16, a voltage divider 17 and at least one measurement result transfer point 18.

[0056] The voltage divider 17 is made up of three resistors 23, 24, 25, wherein the first resistor 23 is connected between the first switch 10 and the second switch 11, the second resistor 24 is connected with a first terminal contact to a first terminal contact of the first resistor 23 and the third resistor 25 is connected with a first terminal contact to a second terminal contact of the first resistor 23.

[0057] A second terminal of the second resistor 24 is connected to the DC voltage source 16 and a second terminal of the third resistor 25 is connected to the ground terminal 26.

[0058] The circuit design establishes a defined voltage value at two specific measuring points 34 and 35, which are connected to two measuring resistors. In the present case, where the DC voltage source 16 provides a 12V DC voltage, a voltage of 8V is established at the first measuring point 34 and a voltage of 4V at the second measuring point 35 during normal operation of the circuit.

[0059] In the event that components within the test device 1 are faulty and fail, the voltage level at the two measuring points 34, 35 shifts in a predictable manner.

[0060] As an example, let's assume the first choke 12 fails. In this case, no test current can flow and both measuring points 34 and 35 will assume a voltage value of 0V.

[0061] If the first switch 10 is defective and no longer provides a switching capability, the voltage value will not be divided between the two measuring points 34 and 35. The first measuring point 34 will then show a voltage of 12V and the second measuring point 35 a voltage of 0V.

[0062] If both switches 10, 11 are closed, the voltage value will be divided symmetrically and both measuring points 34, 35 will show a voltage of 6V.

[0063] If the protection diodes 14 and 15 are defective, they may create a conductive connection. The voltage will then drop to 0V.

[0064] To evaluate the voltages that occur, measuring points 34 and 35 are connected to a measurement result transfer point 18 via a signal conditioning unit 21 and 22. From this point, the signal can be transferred to a filter unit 27 and 28 and an evaluation unit 29. The evaluation unit 29 can be programmed appropriately to evaluate detectable signal states.

[0065] In Fig. 2 shows a section of the test device 1 according to the invention. Fig. 1 shown, in the case where quad analog switches are used.

[0066] Starting from the in Fig. 1 described functioning of the test device 1, considered Fig. 2. The case in which a first and second multiple analog switch 10, 11 is connected between the first winding terminal of the secondary winding 7 and the first terminal 8, and between the second winding terminal of the secondary winding 7 and the second terminal 9. In the present embodiment, this is a first and second quadruple analog switch 10, 11.

[0067] In Fig. Section 2 particularly clarifies the integration of the quadruple analog switches 10 and 11. For this reason, some in Fig. 1. The components of the test equipment described are not shown.

[0068] The quad analog switches 10, 11 are supplied via the 12V DC voltage source 16.

[0069] It is perfectly conceivable that only a four-way analog switch 10, 11 is connected.

[0070] By using quadruple analog switches 10, 11, it is possible to transmit the voltage pulse, which is transferred to the secondary winding 7 of the transformer 5, via different connections to different connection contacts, to which different test objects 2a, 2b, 2c, 2d are connected.

[0071] It is evident that the multiple analog switch has n inputs and n outputs, which can be implemented as bidirectional paths. In the illustrated case of a quad analog switch, n=4. Starting from the n=4 outputs of the first multiple analog switch 10, n=4 first connection contacts can be connected.

[0072] It is also possible to consider the second multiple analog switch 11. This also has n=4 outputs, which can be connected to n=4 second connection contacts.

[0073] n=4 test objects 2a, 2b, 2c, 2d can be connected to the n=4 first and second connection contacts.

[0074] With the test device 1 according to the invention it is therefore possible to examine different test objects 2a, 2b, 2c, 2d for their functionality.

[0075] Furthermore, it is conceivable to perform a higher-order logical investigation if several test objects 2 are connected in series. For example, a fuse followed by a high-voltage contactor is possible. Accordingly, test objects 2 can be examined together if a first capacitor 30 or a second capacitor 31 between the aforementioned test objects 2 should fail. Reference symbol list 1 Testing device 2a, 2b, 2c, 2d Test objects 3 Input for applying a test signal 4 Output for tapping a response signal 5 Transformer 6 Primary winding of the transformer 7 Secondary winding of the transformer 8 first connection contact 9 second connection contact 10 first switch 11 second switch 12 first throttle 13 second throttle 14 first protection diode 15 second protection diode 16 Signal input 17 voltage dividers 18 Measurement result transfer point 19 third switch 20 fourth switch 21 first signal adjustment 22 second signal adjustment 23 first resistance 24 second resistor 25 third resistance 26 Ground connection 27, 28 Filter unit 29 evaluation unit 30 first capacitor 31 second capacitor 32 Pulse voltage source 33 filter unit 34 first measuring point 35 second measuring point

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