System and method for testing capacitors in inverter

Abstract

Systems and methods for testing capacitors in an inverter are disclosed. An example system includes an inverter that converts DC power from a battery to AC power to drive a motor. The inverter includes: a noise filter including a first capacitor connected in series with a second capacitor; and a test circuit configured to test one or more of the first capacitor or the second capacitor. The test circuit includes: a voltage divider including a resistor; a voltage detector configured to measure a voltage at the voltage divider; a switch configured to connect the noise filter with the voltage divider; and one or more controllers configured to control operation of the switch to connect the noise filter with the voltage divider, and configured to determine whether one or more of the first capacitor or the second capacitor is connected with the noise filter based on an output of the voltage detector.

Description

Technical Field

[0001] Various embodiments of this disclosure generally relate to testing capacitors, and more particularly, but not limited to, systems and methods for testing capacitors used in high-voltage circuits such as power inverters for electric vehicles. Background Technology

[0002] Capacitors are widely used in high-voltage applications such as inverters, for various purposes, such as smoothing voltage ripple. Circuits using capacitors may be exposed to environmental factors such as heat, cold, humidity, and shock. Due to these environmental factors, capacitors may detach from the circuit board or fail, which can lead to open circuits in the system and thus degrade system performance.

[0003] This disclosure aims to overcome these challenges. Summary of the Invention

[0004] In some aspects, the technology described herein relates to a system including an inverter that converts DC power from a battery into AC power to drive a motor. The inverter includes: a noise filter comprising a first capacitor connected in series with a second capacitor; and a test circuit configured to test one or more of the first capacitor or the second capacitor, the test circuit including: a voltage divider comprising a resistor; a voltage detector configured to measure the voltage at the voltage divider; a switch configured to connect the noise filter to the voltage divider; and one or more controllers configured to (i) control the operation of the switch to connect the noise filter to the voltage divider, and configured to (ii) determine, based on the output of the voltage detector, whether one or more of the first capacitor or the second capacitor is connected to the noise filter.

[0005] In some respects, the technology described herein relates to a system in which the voltage divider and the noise filter are connected to a positive DC voltage source and a negative DC voltage source.

[0006] In some aspects, the technology described herein relates to a system. The resistor includes a first resistor, a second resistor, a third resistor, and a fourth resistor. The first resistor is connected to a positive DC voltage source. The second resistor is connected to the third resistor, and a voltage detector is connected to the third and fourth resistors.

[0007] In some aspects, the technology described herein relates to a system. The one or more controllers are further configured to: determine that a measured voltage is higher than a first threshold during a time period; and in response to determining that the measured voltage is higher than the first threshold during the time period, determine that the first capacitor and the second capacitor are connected to the noise filter.

[0008] In some aspects, the technology described herein relates to a system. The one or more controllers are further configured to: determine that the measured voltage is below the second threshold for a period of time; and in response to determining that the measured voltage is below the second threshold for a period of time, determine that the first capacitor is disconnected from the noise filter.

[0009] In some aspects, the technology described herein relates to a system. The one or more controllers are further configured to: determine that a measured voltage is higher than a third threshold over a time period. This third threshold is greater than a first threshold used to determine that the first capacitor is disconnected; and in response to determining that the measured voltage is higher than the third threshold, determine that the second capacitor is disconnected from the noise filter.

[0010] In some respects, the technology described herein relates to a system. The one or more controllers are further configured to: determine that the measured voltage is zero volts; and in response to determining that the measured voltage is zero volts, determine that the first capacitor and the second capacitor are disconnected from the noise filter.

[0011] In some aspects, the technology described herein relates to a system. The test circuit further includes: an additional voltage divider comprising an additional resistor; and an additional voltage detector configured to measure an additional voltage at the additional voltage divider. The one or more controllers are further configured to (iii) determine, based on the output of the voltage detector and an additional output of the additional voltage detector, whether one or more of the first capacitor or the second capacitor is operating at a reduced capacitance.

[0012] In some respects, the technology described herein relates to a system. Determining whether one or more of the first capacitor or the second capacitor are operating at a reduced capacitance involves comparing the output with the other output.

[0013] In some respects, the technology described herein relates to a system in which the values ​​of the resistors are 500 KOhm, 500 KOhm, 500 KOhm, and 5 KOhm.

[0014] In some aspects, the technology described herein relates to a system that further includes: a battery configured to supply DC power to an inverter; and a motor configured to receive AC power from the inverter to drive the motor. The system is provided as a vehicle including the inverter, the battery, and the motor.

[0015] In some aspects, the technology described herein relates to a method comprising operating with one or more controllers, the operation including: connecting a first capacitor and a second capacitor of a noise filter to a voltage divider; measuring the voltage at the first capacitor and the second capacitor at a voltage detector connected to the voltage divider; comparing the measured voltage to a threshold voltage; and, in response to the comparison, determining whether one or more of the first capacitor or the second capacitor is connected or disconnected from the noise filter.

[0016] In some respects, the techniques described herein relate to a method. Determining whether one or more of the first capacitor or the second capacitor are connected or disconnected from the noise filter includes determining that the first capacitor and the second capacitor are connected to the noise filter based on a measured voltage greater than a threshold voltage.

[0017] In some respects, the techniques described herein relate to a method. Determining whether one or more of the first capacitor or the second capacitor are connected or disconnected from the noise filter includes determining that the first capacitor is disconnected from the noise filter based on a measured voltage being less than a threshold voltage.

[0018] In some respects, the techniques described herein relate to a method. Determining whether one or more of the first capacitor or the second capacitor are connected or disconnected from the noise filter includes determining that the first capacitor and the second capacitor are connected to the noise filter based on a measured voltage of zero volts.

[0019] In some aspects, the technology described herein relates to a system comprising: a test circuit configured to test one or more capacitors, the test circuit comprising: a voltage divider; a voltage detector configured to measure voltages at a first capacitor and a second capacitor as measured voltages; a switch configured to connect the first capacitor and the second capacitor to the voltage divider; and one or more controllers configured to (i) control the operation of the switch to connect the first capacitor and the second capacitor to the voltage divider, and configured to (ii) determine, based on the output of the voltage detector, whether one or more of the first capacitor or the second capacitor is connected to a main circuit.

[0020] In some aspects, the technology described herein relates to a system. The one or more controllers are further configured to: determine that a measured voltage is higher than a first threshold during a time period; and in response to determining that the measured voltage is higher than the first threshold during the time period, determine that the first capacitor and the second capacitor are connected to the main circuit.

[0021] In some aspects, the technology described herein relates to a system. The one or more controllers are further configured to: determine that the measured voltage is below the second threshold for a period of time; and in response to determining that the measured voltage is below the second threshold for a period of time, determine that the first capacitor is disconnected from the main circuit.

[0022] In some aspects, the technology described herein relates to a system. The one or more controllers are further configured to: determine that a measured voltage is higher than a third threshold over a time period. This third threshold is greater than a first threshold used to determine that the first capacitor is disconnected; and in response to determining that the measured voltage is higher than the third threshold, determine that the second capacitor is disconnected from the main circuit.

[0023] In some respects, the technology described herein relates to a system. The one or more controllers are further configured to: determine that the measured voltage is zero volts; and in response to determining that the measured voltage is zero volts, determine that the first capacitor and the second capacitor are disconnected from the main circuit.

[0024] Further objects and advantages of the disclosed embodiments will be set forth in part in the description which follows, and will be apparent in part from the description, or may be learned by practice of the disclosed embodiments. The objects and advantages of the disclosed embodiments will be realized and achieved by means of the elements and combinations particularly pointed out in the appended claims.

[0025] It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and do not limit the claimed disclosed embodiments. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate various exemplary embodiments and, together with the description, serve to explain the principles of the disclosed embodiments.

[0027] Figure 1 An exemplary system infrastructure for a vehicle including a combination of inverters and converters, according to one or more embodiments, is described.

[0028] Figure 2 A schematic diagram of the electrical power of a three-phase inverter in a connected system according to one or more embodiments is depicted.

[0029] Figure 3 Specific implementations of computer systems capable of performing the techniques presented herein, according to one or more embodiments, are described.

[0030] Figure 4 An exemplary electrical schematic diagram of an inverter is depicted according to one or more embodiments.

[0031] Figure 5 An exemplary electrical schematic diagram of a test circuit for one or more capacitors is depicted according to one or more embodiments.

[0032] Figure 6 An exemplary method for testing one or more capacitors according to one or more embodiments is described.

[0033] Figures 7 to 10 Exemplary graphs depict various signals in a test circuit for testing one or more capacitors, according to one or more embodiments. Detailed Implementation

[0034] Both the foregoing general description and the following detailed description are exemplary and interpretive only, and do not limit the claimed features. As used herein, the terms “comprises,” “comprising,” “has,” “having,” “includes,” “including,” or other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements may include not only those elements but also other elements not expressly listed or inherent to such a process, method, article, or apparatus. In this disclosure, unless otherwise stated, relative terms (such as, for example, “about,” “substantially,” and “approximately”) are used to indicate possible ±10% variation in the stated values. In this disclosure, unless otherwise stated, any numerical value may include possible ±10% variation in the stated values.

[0035] The terminology used below may be interpreted in its broadest and most reasonable manner, although it is used in conjunction with a detailed description of certain specific instances of this disclosure. In fact, some terms may even be emphasized below; however, any term intended to be interpreted in any constrained manner will be explicitly and specifically defined in this Detailed Description section.

[0036] Various embodiments of this disclosure generally relate to testing one or more capacitors, and more particularly, but not limited to, systems and methods for testing capacitors used in high-voltage circuits such as those used in inverters used in electric vehicles. After inverter circuitry is deployed in a vehicle, some test systems lack the ability to test capacitors within the inverter circuitry.

[0037] In contrast, one or more embodiments can be applied to capacitors installed in circuits such as inverters (“main circuits”). A test circuit can determine whether one or more capacitors are disconnected from the main circuit or have experienced other faults by measuring one or more voltages across the capacitors over time.

[0038] Although the examples discussed in this article describe one or more capacitors in a test circuit (such as an inverter), as regarding Figures 1 to 4 This is what has been discussed, but this disclosure is not limited thereto. However, one or more embodiments can be used to test capacitors mounted in any circuit.

[0039] Figure 1 Exemplary system infrastructure for a vehicle including a combined inverter and converter, according to one or more embodiments, is depicted. Alternatively, the inverter may be an inverter without a converter. Within the context of this disclosure, both an inverter without a converter and a combined inverter and converter can be referred to as an inverter. Figure 1 As shown, electric vehicle 100 may include an inverter 110, a motor 190, and a battery 195. Inverter 110 may include components for receiving electrical power from an external source and outputting electrical power to charge the battery 195 of electric vehicle 100. For example, inverter 110 may convert DC power from the battery 195 in electric vehicle 100 into AC power to drive the motor 190 of electric vehicle 100 (e.g., to rotate it), but embodiments are not limited thereto. For example, inverter 110 may be bidirectional and may convert DC power to AC power or AC power to DC power, such as during regenerative braking. Inverter 110 may be a three-phase inverter, a single-phase inverter, or a multi-phase inverter.

[0040] Figure 2 A schematic diagram of the electrical power of a three-phase inverter module according to one or more embodiments is depicted. Figure 1 and Figure 2 As shown, inverter 110 can be connected to battery 195 and motor 190. Battery 195 can be any power supply device, and motor 190 can be any load. Inverter 110 may include a first three-phase switch group 210 and a second three-phase switch group 220. The first phase U may be associated with ΦA, including switches Q1 and Q4; the second phase V may be associated with ΦB, including switches Q3 and Q6; and the third phase W may be associated with ΦC, including switches Q5 and Q2, as shown. Figure 2 As shown. The first three-phase switch group 210 may include a first phase switch Q1, a second phase switch Q3, and a third phase switch Q5. The second three-phase switch group 220 may include a first phase switch Q4, a second phase switch Q6, and a third phase switch Q2. Switches Q1 to Q6 may be metal-oxide-semiconductor field-effect transistors (MOSFETs), for example, but not limited to.

[0041] The first three-phase switch group 210 and the second three-phase switch group 220 can be controlled by the controller 300. Figure 3The PWM signal generated (as shown) is used to drive the motor 190 to convert the DC power delivered via the input terminal group 285 at capacitor 230 into three-phase AC power at the outputs U, V, and W via the output terminal group 295. Additionally, although... Figure 1 and Figure 2 A three-phase inverter is shown, but this disclosure is not limited thereto and may include single-phase or multi-phase inverters.

[0042] Figure 3 Specific implementations of a controller 300, according to one or more embodiments, capable of performing the techniques presented herein are described. For example, the controller 300 can control regarding... Figure 5 The capacitor test circuit is discussed further. In some cases, the controller 300 can operate as a detection circuit for the voltage associated with one or more capacitors. For example, a low-voltage output from a voltage divider can be connected to an input of the controller 300 to determine whether one or more capacitors are connected, as discussed further herein.

[0043] Any suitable system infrastructure can be implemented to achieve control of the inverter. Figure 3 The following discussion provides a brief general description of a suitable computing environment in which this disclosure can be implemented. In one embodiment, any of the disclosed systems, methods, and / or graphical user interfaces can be implemented using... Figure 3 The computing systems depicted herein are implemented or executed by computing systems consistent with or similar to those described herein. While not strictly necessary, embodiments of this disclosure are described within the context of computer-executable instructions, such as routines executed by data processing devices (e.g., server computers, wireless devices, and / or personal computers). Those skilled in the art will understand that embodiments of this disclosure can be implemented in other communication configurations, data processing configurations, or computer system configurations, including network devices, handheld devices (personal digital assistants (“PDAs”), wearable computers, various types of cellular or mobile phones (including Voice over IP (“VoIP”) phones), dumb terminals, media players, gaming devices, virtual reality devices, multiprocessor systems, microprocessor-based or programmable consumer electronics, set-top boxes, network PCs, minicomputers, mainframes, etc. In practice, the terms “computer,” “server,” etc., are generally used interchangeably herein and refer to any of the aforementioned devices and systems, as well as any data processor.

[0044] Embodiments of this disclosure can be embodied in special-purpose computers and / or data processors that are specifically programmed, configured, and / or constructed to execute one or more computer-executable instructions as explained in detail herein. While embodiments of this disclosure (such as certain functions) are described as performing only on a single device, this disclosure can also be practiced in a distributed environment where functions or modules are shared among different processing devices connected via communication networks such as local area networks (“LANs”), wide area networks (“WANs”), and / or the Internet. Similarly, the techniques presented herein involving multiple devices can be implemented in a single device. In a distributed computing environment, program modules can reside in local and / or remote memory storage devices.

[0045] Embodiments of this disclosure may be stored and / or distributed on non-transparent computer-readable media, including magnetically or optically readable computer optical discs, hardware-connected or pre-programmed chips (e.g., EEPROM semiconductor chips), nanotechnology memories, biological memories, or other data storage media. Alternatively, computer-implemented instructions, data structures, screen displays, and other data under embodiments of this disclosure may be distributed via the Internet and / or other networks (including wireless networks); via signals propagating over a time period on a propagation medium (e.g., one or more electromagnetic waves, sound waves, etc.); and / or they may be provided on any analog or digital network (packet switching, circuit switching, or other schemes).

[0046] The controller 300 may include a set of instructions that can be executed to cause the controller 300 to perform any or more of the methods or computer-based functions disclosed herein. The controller 300 may operate as a stand-alone device or may be connected to other computer systems or peripheral devices, for example, via a network.

[0047] In a networked deployment, controller 300 can operate as a server, or as a client in a server-client user network environment, or as a peer-to-peer (or distributed) computer system in a peer-to-peer (or distributed) network environment. Controller 300 can also be implemented as or integrated into various devices, such as personal computers (PCs), tablet PCs, set-top boxes (STBs), personal digital assistants (PDAs), mobile devices, handheld computers, laptop computers, desktop computers, communication equipment, wireless telephones, landline telephones, control systems, cameras, scanners, fax machines, printers, pagers, personal trusted devices, network devices, network routers, switches or bridges, or any other machine capable of executing a set of instructions (sequentially or otherwise) specifying the actions to be taken by that machine. In a particular implementation, controller 300 can be implemented using electronic devices that provide voice, video, or data communication. Furthermore, while controller 300 is exemplified as a single system, the term "system" should also be understood to include any collection of systems or subsystems that individually or jointly execute one or more sets of instructions to perform one or more computer functions.

[0048] like Figure 3 As shown, controller 300 may include processor 302, such as a central processing unit (CPU), graphics processing unit (GPU), or both. Processor 302 can be a component in a variety of systems. For example, processor 302 can be part of a standard computer. Processor 302 can be one or more general-purpose processors, digital signal processors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), servers, networks, digital circuits, analog circuits, combinations thereof, or other devices now known or later developed for analyzing and processing data. Processor 302 can implement software programs, such as manually generated (i.e., programmed) code.

[0049] Controller 300 may include memory 304 communicatable via bus 308. Memory 304 may be main memory, static memory, or dynamic memory. Memory 304 may include, but is not limited to, computer-readable storage media, such as various types of volatile and non-volatile storage media, including but not limited to random access memory, read-only memory, programmable read-only memory, electrically programmable read-only memory, electrically erasable read-only memory, flash memory, magnetic tape or disk, optical media, etc. In one embodiment, memory 304 includes a cache or random access memory for processor 302. In alternative embodiments, memory 304 is decoupled from processor 302, such as processor cache memory, system memory, or other memory. Memory 304 may be an external storage device or database for storing data. Examples include hard disk drives, optical discs (“CDs”), digital video discs (“DVDs”), memory cards, memory sticks, floppy disks, universal serial bus (“USB”) storage devices, or any other device operable for storing data. Memory 304 is operable to store instructions executable by processor 302. The functions, actions, or tasks illustrated in the figures or described herein can be performed by processor 302, which executes instructions stored in memory 304. These functions, actions, or tasks are independent of a specific type of instruction set, storage medium, processor, or processing strategy, and can be performed by software, hardware, integrated circuits, firmware, microcode, etc., operating individually or in combination. Similarly, processing strategies can include multiprocessing, multitasking, parallel processing, etc.

[0050] As depicted, controller 300 may further include display 310, such as a liquid crystal display (LCD), organic light-emitting diode (OLED), flat panel display, solid-state display, cathode ray tube (CRT), projector, printer, or other display device now known or later developed for outputting defined information. Display 310 may serve as an interface for a user to view the functions of processor 302, or specifically as an interface with software stored in memory 304 or drive unit 306.

[0051] Alternatively or additionally, the controller 300 may include an input device 312 configured to allow a user to interact with any component of the controller 300. The input device 312 may be a numeric keypad, keyboard, or cursor control device (such as a mouse or joystick), touchscreen display, remote control, or any other device operable to interact with the controller 300.

[0052] The controller 300 may also, or alternatively, include a drive unit 306 implemented as a disk or optical disc drive. The drive unit 306 may include a computer-readable medium 322 in which one or more sets of instructions 324 (e.g., software) may be embedded. Further, the instructions 324 may embody one or more of the methods or logic described herein. The instructions 324 may reside wholly or partially within memory 304 and / or processor 302 during execution by the controller 300. Memory 304 and processor 302 may also include computer-readable media as discussed above.

[0053] In some systems, computer-readable medium 322 includes instructions 324 or receives and executes instructions 324 in response to a propagated signal, enabling devices connected to network 370 to transmit voice, video, audio, images, or any other data via network 370. Furthermore, instructions 324 may be transmitted or received via communication port or interface 320 through network 370 and / or using bus 308. Communication port or interface 320 may be part of processor 302 or may be a separate component. Communication port or interface 320 may be formed in software or may be a physical connector in hardware. Communication port or interface 320 may be configured to connect to network 370, external media, display 310, or any other component of controller 300, or a combination thereof. Connection to network 370 may be a physical connection (such as a wired Ethernet connection) or may be established wirelessly, as discussed below. Similarly, additional connections to other components of controller 300 may be physical connections or may be established wirelessly. Network 370 may alternatively be directly connected to bus 308.

[0054] Although computer-readable medium 322 is shown as a single medium, the term "computer-readable medium" can include a single medium or multiple media (such as a centralized or distributed database and / or associated caches and servers) storing one or more sets of instructions. The term "computer-readable medium" can also include any medium capable of storing, encoding, or carrying a set of instructions for execution by a processor or causing a computer system to perform any or more of the methods or operations disclosed herein. Computer-readable medium 322 can be non-transitory and can be tangible.

[0055] Computer-readable medium 322 may include solid-state memory, such as a memory card, or other package housing one or more non-volatile read-only memories. Computer-readable medium 322 may be random access memory or other volatile rewritable memory. Additionally or alternatively, computer-readable medium 322 may include magneto-optical or optical media, such as magnetic disks or magnetic tapes, or other storage devices for capturing carrier signals (such as signals transmitted via a transmission medium). Digital file attachments to emails or other self-contained information archives or archive sets can be considered as distribution media as tangible storage media. Therefore, this disclosure is considered to include any one or more of computer-readable media or distribution media in which data or instructions can be stored, as well as other equivalents and successor media.

[0056] In alternative embodiments, specialized hardware implementations (such as application-specific integrated circuits, programmable logic arrays, and other hardware devices) may be configured to implement one or more of the methods described herein. Applications that may include various implementations of the apparatus and systems can broadly encompass a wide range of electronic and computer systems. One or more embodiments described herein may be implemented using two or more specific interconnected hardware modules or devices having associated control and data signals that can be transferred between or through modules, or as part of an application-specific integrated circuit. Therefore, this system encompasses software, firmware, and hardware implementations.

[0057] Controller 300 can be connected to network 370. Network 370 may define one or more networks, including wired or wireless networks. Wireless networks may be cellular telephone networks, 802.11, 802.16, 802.20, or WiMAX networks. Further, such networks may include public networks (such as the Internet), private networks (such as intranets), or combinations thereof, and may utilize a variety of networking protocols now available or developed later, including but not limited to TCP / IP-based networking protocols. Network 370 may include wide area networks (WANs) (such as the Internet), local area networks (LANs), campus area networks, metropolitan area networks, direct connections (such as via a universal serial bus (USB) port), or any other network that allows data communication. Network 370 may be configured to couple one computing device to another to enable data communication between the devices. Typically, network 370 may be able to use any form of machine-readable medium to transfer information from one device to another. Network 370 may include communication methods through which its information can travel between computing devices. Network 370 may be divided into subnets. A subnet can allow access to all other components in other components connected to it, or a subnet can restrict access between components. Network 370 can be viewed as a public or private network connection and can include, for example, virtual private networks or encryption or other security mechanisms employed on the public Internet.

[0058] According to various embodiments of this disclosure, the methods described herein can be implemented by software programs executable by a computer system. Further, in exemplary non-limiting embodiments, the implementation may include distributed processing, component / object distributed processing, and parallel processing. Alternatively, virtual computer system processing may be configured to implement one or more of the methods or functionalities described herein.

[0059] Although this specification describes components and functions that may be implemented in specific implementations with reference to particular standards and protocols, this disclosure is not limited to such standards and protocols. For example, standards for transmission over the Internet and other packet-switched networks (e.g., TCP / IP, UDP / IP, HTML, and HTTP) represent examples of prior art. Such standards are periodically superseded by faster or more efficient equivalents with substantially the same functionality. Therefore, alternative standards and protocols with the same or similar functionality as those disclosed herein are considered their equivalents.

[0060] It will be understood that, in one embodiment, the steps of the method discussed are performed by a suitable processor (or processors) of a processing (i.e., computer) system that executes instructions (computer-readable code) stored in a storage device. It will also be understood that this disclosure is not limited to any particular specific implementation or programming technique, and that any suitable technique used to implement the functionality described herein may be used to implement this disclosure. This disclosure is not limited to any particular programming language or operating system.

[0061] Figure 4 An exemplary electrical schematic diagram of an inverter 400 according to one or more embodiments is depicted. Inverter 400 is a multiphase inverter configured to receive direct current (DC) power, convert the DC power to multiphase alternating current (AC) power using one or more phase switches, and supply the AC power to one or more motor windings of an electric motor. As further discussed herein, inverter 400 may include, for example, components that can be used with respect to… Figure 5 The techniques discussed are used to test one or more capacitors.

[0062] Inverter 400 includes a positive DC voltage source 402, a negative DC voltage source 404, a large-capacity capacitor 406, a noise filter (Y-cap) 410, an inductor 408, a large-capacity capacitor 416, a noise filter (Y-cap) 418, a discharge circuit 420, a voltage measurement circuit 422, a phase switch group 450a-f, a current measurement device 426, and an electric motor 428. In the depicted example, inverter 400 receives power via the positive DC voltage source 402 and the negative DC voltage source 404 (e.g., via battery 140); reduces ripple and noise in the power via one or more of the large-capacity capacitor 406, the noise filter 410, the inductor 408, the large-capacity capacitor 416, or the noise filter 418; converts the power to AC power via the phase switch group 450a-f; and provides the converted power to one or more windings in electric motor 428.

[0063] Noise can be introduced into the system and carried on the positive DC voltage source 402 and / or the negative DC voltage source 404. Noise filters 410 and 418 can be used to remove such noise. Noise filters 410 and 418 each may include two capacitors connected in series, which filter noise on the positive DC voltage source 402 and / or the negative DC voltage source 404. As depicted, noise filter 410 includes capacitors 430 and 432. Capacitor 430 is connected to the positive DC voltage source 402, ground 436, and capacitor 432. Noise filter 418 includes capacitors 440 and 442. Capacitor 440 is connected to the positive DC voltage source 402, ground 446, and capacitor 442.

[0064] Capacitors 430, 432, 440, and 442 can filter high-frequency noise that may couple with the high voltage on the positive DC voltage source 402 and / or the low voltage on the negative DC voltage source 404, thereby reducing EMI / RFI noise and related side effects. In some cases, capacitors 430, 432, 440, and 442 may be safety-certified capacitors. Such capacitors are useful when high voltage is used in the circuit, such as in battery charging circuits.

[0065] The reliability of components within inverter 400 can be a concern, especially in harsh environments such as those in electric vehicles. For example, one or more of capacitors 430, 432, 440, or 442 may be disconnected from inverter 400 (e.g., one or more of positive DC voltage source 402, negative DC voltage source 404, or ground 436) due to shock or vibration. Such disconnection may cause inverter 400 to malfunction as designed.

[0066] Faulty or disconnected capacitors can be tested at the factory (e.g., before the inverter circuitry is placed in the vehicle or before the vehicle is transported). However, such tests may not be able to account for faults occurring in the field.

[0067] In contrast, one or more embodiments can automatically test the capacitors in the inverter circuitry without user intervention after the capacitors have been installed in the electric vehicle. In some cases, capacitor testing may be performed during or after targeted shock or vibration testing. For example, shock and vibration testing can be performed using a system that includes circuitry such as inverter 400, as such systems may be designed to be highly resistant to the effects of shock and vibration. Therefore, one or more embodiments can test one or more of capacitors 430, 432, 440, or 442.

[0068] Inverter 400 may also include one or more large-capacity capacitors 406 and 416. These large-capacity capacitors may prevent the output voltage from dropping too low during periods when current is unavailable. In some cases, one or more embodiments may be used to test whether large-capacity capacitors 406 and 416 are connected to inverter 400.

[0069] Discharge circuit 420 can be used to release unused power or discharge power in the event of a fault. Voltage measurement circuit 422 can be used to detect high voltage on inverter 400. Measures can be taken, for example, via controller 300, to disable the circuit when a high voltage is detected.

[0070] Phase switch groups 450a-f perform DC-to-AC conversion. As depicted, each phase switch group 450a-f includes a phase switch (e.g., a transistor), a current sensor, and a temperature sensor. The current sensor measures the current flowing through each corresponding phase switch. The temperature sensor measures the temperature at one or more locations within the corresponding phase switch. The current and temperature measurements are provided to controller 300. If the temperature exceeds the acceptable range, action can be taken via controller 300.

[0071] The current flowing to the windings of the electric motor 428 can be measured using a current measuring device 426. The current measurement result can be provided to the controller 300, which in turn can adjust the operation of the electric motor 428.

[0072] Figure 5An exemplary electrical schematic diagram of a test circuit 500 for one or more capacitors is depicted according to one or more embodiments. In the depicted example, switch 540 is turned on and / or off, and one or more voltages detected by voltage detectors 560 and 580 are analyzed to determine whether capacitors 530 and / or 532 are disconnected or non-operational.

[0073] The test circuit 500 includes a battery 140, a ground 534, a capacitor 530, a capacitor 532, a switch 540, a control signal 544, a voltage divider 550, a voltage detector 560, a voltage divider 570, a voltage detector 580, and a controller 300. Capacitor 530 may correspond to capacitor 430 or capacitor 440 in inverter 400. Capacitor 532 may correspond to capacitor 432 or capacitor 442 in inverter 400.

[0074] Controller 300 can control the operation of switch 540. As further explained below, test circuit 500 can be operated by controller 300 to cause control signal 544 to open or close switch 540, and to measure one or more voltages detected at voltage detectors 560 and / or 580 when switch 540 is closed. Switch 540 can be any type of switch. In one example, switch 540 can be a relay due to its handling of high voltage and current. In other cases, switch 540 may be a MOSFET switch.

[0075] Each of voltage dividers 550 and 570 may include multiple resistors. For example, as depicted, voltage divider 550 includes resistors 552, 554, 556, and 558, and voltage divider 570 includes resistors 572, 574, 576, and 578. However, any number of resistors is possible. Voltage divider 550 may include capacitor 562, and voltage divider 570 may include capacitor 582. Voltage dividers 550 and 570 are each connected to voltage detectors 560 and 580, respectively. Voltage divider 570 and voltage detector 580 may not always be used, and in some cases, they can be used to provide redundancy in the event of a failure. However, in some cases, voltage dividers 550 and 570 operate together, for example, to detect drift of capacitor 530 or capacitor 532.

[0076] Signals received from voltage detectors 560 and 580 may indicate whether capacitors 530 and / or 532 are connected or disconnected from circuit 500, as per [reference to...]. Figure 6 Further discussion follows. Voltage detectors 560 and 580 may each output a corresponding signal to controller 300 indicating the detected voltage.

[0077] When switch 540 is open, the voltage detected at voltage detector 560 is a scaled voltage based on the DC positive source voltage, depending on the values ​​of specific resistors 556 and 558 in voltage divider 550. In contrast, when switch 540 is closed, the voltage detected at voltage detector 560 varies depending on whether capacitors 530 and 532 are connected to the circuit and operating normally, for example, as per [reference to...]. Figures 6 to 10 The subject of discussion.

[0078] In this example, the values ​​of resistors 552, 554, 556, and 558 might be 500KOhm, 500KOhm, 500KOhm, and 5KOhm, respectively. The resistor values ​​can be adjusted to make the voltage divider's output compatible with voltage sensing devices; in some cases, this may involve the controller. In some cases, additional resistors can be used if the power rating necessitates that the load be shared through an additional number of resistors.

[0079] The voltage detector 560 can be implemented via a comparator and / or a controller. For example, the comparator can receive the input of the voltage detector 560 and compare the voltages. In other cases, the controller 300 may include an input configured to perform detection. In higher voltage applications, an additional buffer circuit system can be used.

[0080] The output of voltage divider 570 is based on the value of resistor 578, compared to the values ​​of resistors 572, 574, and 576. In this example, the values ​​of resistors 572, 574, 576, and 578 may be 500KOhm, 500KOhm, 500KOhm, and 5KOhm, respectively.

[0081] Figure 6 An exemplary method 600 for testing one or more capacitors according to one or more embodiments is depicted. For illustrative purposes, method 600 is discussed with respect to test circuitry 500 controlled by controller 300. However, method 600 can be applied to other capacitor test circuits and / or implemented by different controllers. Furthermore, while method 600 depicts various operations, not all of the listed operations can be performed and / or some operations can be repeated where appropriate.

[0082] At block 605, method 600 may involve connecting one or more capacitors of the noise filter to a voltage divider. For example, returning to... Figure 5 The controller 300 causes the switch 540 to close, thereby connecting capacitors 530 and 532 to the voltage divider 550.

[0083] At block 610, method 600 may involve measuring the voltage at one or more capacitors at a voltage detector connected to a voltage divider. Continuing the example, voltage detector 560 receives the voltage at the capacitors. The received voltage can be transmitted to controller 300.

[0084] The voltage output from voltage divider 550 is scaled based on the characteristic resistors used in voltage divider 550 (e.g., resistors 552, 554, 556, and 558). On one hand, voltage measurements may be taken over a period of time or within a window. In this example, a 200-millisecond (ms) window is used. Multiple samples can be obtained, and the sampling frequency can be adjusted.

[0085] At block 615, method 600 may involve comparing the measured voltage with a threshold voltage. Controller 300 compares the measured voltage received at block 610 with one or more threshold voltages. As discussed herein, the measured voltage can determine whether each of capacitors 530 and 532 is functioning properly and connected to the circuit, or is faulty or disconnected. Multiple different thresholds may be used, as discussed below.

[0086] At block 620, method 600 may involve responding to a comparison to determine whether one or more of the capacitors are disconnected from the noise filter. Different scenarios may exist, such as capacitors 530 and 532 both connected, capacitor 530 being disconnected, capacitor 532 being disconnected, and both capacitors 530 and 532 being disconnected.

[0087] In one instance, at block 620, method 600 might involve determining whether capacitors 530 and 532 are connected. For example, if capacitors 530 and 532 are connected, the detected voltage might increase above a first threshold when switch 540 is closed. (See also: [link to relevant documentation]). Figure 7 As further demonstrated, a detected voltage higher than the first threshold during this time period may indicate that capacitors 530 and 532 are connected to the circuit.

[0088] In another instance, at block 620, method 600 might involve determining that capacitor 530 is disconnected. For example, if capacitor 530 is disconnected, the detected voltage might drop below or less than a second threshold. (See also: Regarding...) Figure 8 As further demonstrated, a detected voltage below the second threshold during this time period may indicate that capacitor 530 is disconnected from circuit 500.

[0089] In yet another instance, at block 620, method 600 might involve determining that capacitor 532 is disconnected. For example, if capacitor 532 is disconnected, the voltage detected when switch 540 is turned off might increase. (See also: ...) Figure 9 As further demonstrated, a detected voltage exceeding the third threshold during this time period may indicate that capacitor 532 is disconnected from circuit 500. The third threshold may be greater than the first threshold discussed above.

[0090] In yet another instance, method 600 might involve determining that neither capacitor 530 nor capacitor 532 is connected. For example, if the detected voltage is zero volts, then neither capacitor 530 nor 532 is connected.

[0091] In yet another instance, method 600 may involve determining that one or more of capacitors 530 or 532 are connected but operating with reduced capacitance, or have “drift.” One or both of capacitors 530 and 532 may have “drift.” In this case, a voltage divider 570 and a voltage detector 580 are used to determine an additional voltage. This additional voltage is then compared to the voltage measured via a voltage divider 550 and a voltage detector 560.

[0092] Continuing with the example, if one or more of the first capacitor or the second capacitor are operating with reduced capacitance, the voltage measured at voltage detector 560 will be different from the voltage measured at voltage detector 580.

[0093] Figure 7 Exemplary graph 700 depicts various signals in a test circuit for testing one or more capacitors, according to one or more embodiments. In the depicted example, capacitors 530 and 532 are operative and connected.

[0094] Graph 700 includes graphs 730 and 740, each representing the measurement result of voltage 710 over time 720. The signal represented by graph 730 represents the output of the voltage detector, and the signal represented by graph 740 represents the control signal of switch 540.

[0095] In the depicted example, zero voltage on graph 740 indicates that switch 540 is open, while a non-zero (e.g., 1 volt) voltage on graph 740 indicates that switch 540 is closed. Graph 740 shows that the control signal for switch 540 is initially open and remains so until approximately 2 seconds, at which point switch 540 is closed.

[0096] The signal represented by Figure 730 indicates that the voltage detected by the voltage detector initially rises from 0 volts to approximately 1.3 volts. This value can be determined from a positive DC voltage, which in this example is 400 volts across voltage divider 550. For example, if the given value of each of resistors 552, 554, and 556 is 500 ohms, and the value of resistor 558 is 5 ohms, the measured voltage when switch 540 is open is approximately 1.3 volts.

[0097] Then, in this example, when switch 540 is turned off after approximately 2 seconds, the voltage rises further to a peak of approximately 2 volts. This value can be determined by considering that when capacitors 530 and 532 are both connected, operational, and have equal values, a positive DC voltage of 400 volts is evenly distributed between capacitors 530 and 532. Therefore, a value of 200 volts is provided to voltage divider 550, and the voltage is divided according to the resistance values ​​of resistors 556 and 558 (500 KOhm and 5 KOhm, respectively).

[0098] As depicted, switch 540 remains open for a period of approximately 200 ms. During this period, the signal, as shown in graph 730, decreases as capacitors 530 and 532 discharge through the resistors of the voltage divider.

[0099] To detect this rise in the signal represented by graph 730, a threshold can be used. Above this threshold, capacitors 530 and 532 are determined to be operational. The exact threshold may vary depending on the configuration of circuit 500, but in the depicted example, the threshold may be approximately 1.6 to 1.7 volts.

[0100] Figure 8 An exemplary graph 800 depicts various signals in a test circuit for one or more capacitors according to one or more embodiments. In the depicted example, capacitor 530 is neither operational nor disconnected.

[0101] Graph 800 includes graphs 830 and 840, each representing the measurement result of voltage 810 over time 820. The signal represented by graph 830 represents the output of the voltage detector, and the signal represented by graph 840 represents the control signal of switch 540.

[0102] In the depicted example, zero voltage on graph 840 indicates that switch 540 is open, while a non-zero (e.g., 1 volt) voltage on graph 840 indicates that switch 540 is closed. Graph 840 shows that the control signal for switch 540 is initially open and remains so until approximately 2 seconds, at which point switch 540 is closed.

[0103] The signal represented by Figure 830 indicates that the voltage detected by the voltage detector initially rises from 0 volts to approximately 1.3 volts. Then, in this example, when switch 540 is turned off after approximately 2 seconds, the voltage drops back to approximately 0 volts.

[0104] If capacitor 530 is open, the value delivered to voltage divider 550 is zero volts. Therefore, resistors 556 and 558 are short-circuited. As depicted, switch 540 remains open for a period of approximately 200 ms. During this period, the signal represented by graph 830 increases as current flows through the resistors of the voltage divider charging capacitor 532. If the period is long enough, capacitor 532 will be fully charged and the voltage will increase to approximately 1.3 volts.

[0105] To detect a decrease in the signal represented by graph 830, a threshold can be used. Below this threshold, it is determined that capacitor 530 is non-operational or disconnected. The exact threshold may vary depending on the configuration of circuit 500, but in the depicted example, the threshold may be approximately 0.1–0.2 volts.

[0106] Figure 9 An exemplary graph 900 depicts various signals in a test circuit for one or more capacitors according to one or more embodiments. In the depicted example, capacitor 532 is neither operational nor disconnected.

[0107] Graph 900 includes graphs 930 and 940, each representing the measurement result of voltage 910 over time 920. The signal represented by graph 930 represents the output of the voltage detector, and the signal represented by graph 940 represents the control signal of switch 540.

[0108] In the depicted example, zero voltage on graph 940 indicates that switch 540 is open, while a non-zero (e.g., 1 volt) voltage on graph 940 indicates that switch 540 is closed. Graph 940 shows that the control signal for switch 540 is initially open and remains so until approximately 2 seconds, at which point switch 540 is closed.

[0109] The signal represented by Figure 930 indicates that the voltage detected by the voltage detector initially rises from 0 volts to approximately 1.3 volts. Then, in this example, when switch 540 is turned off after approximately 2 seconds, the voltage rises further to a peak of approximately 4 volts.

[0110] The value of this 4 volt can be determined by considering the following: when capacitors 530 and 532 are both connected and operational, a positive DC voltage of 400 volts is supplied to voltage divider 550 and distributed according to the resistance values ​​of resistors 556 and 558 (500 KOhm and 5 KOhm, respectively).

[0111] As depicted, switch 540 remains open for a period of approximately 200 ms. During this period, the signal, as shown in graph 730, decreases as capacitor 530 discharges through the resistor of the voltage divider.

[0112] To detect this rise in the signal represented by graph 730, a threshold can be used. Above this threshold, capacitors 530 and 532 are determined to be operational. The exact threshold may vary depending on the configuration of circuit 500, but in the depicted example, the threshold may be approximately 3.4 to 3.6 volts.

[0113] Figure 10 An exemplary graph 1000 depicts various signals in a test circuit for one or more capacitors according to one or more embodiments, each representing a measurement of voltage 1010 over time 1020. In the depicted example, capacitor 530 is partially operational with a 50% drift, indicating that 50% of the specified capacitance is available.

[0114] Graph 1000 includes graphs 1030 and 1040. The signal represented by graph 1030 represents the output of the voltage detector measurement, and the signal represented by graph 1040 represents the control signal of switch 540.

[0115] In the depicted example, zero voltage on graph 1040 indicates that switch 540 is open, while a non-zero (e.g., 1 volt) voltage on graph 1040 indicates that switch 540 is closed. Graph 1040 shows that the control signal for switch 540 is initially open and remains so until approximately 2 seconds, at which point switch 540 is closed.

[0116] The signal represented by Figure 1030 indicates that the voltage detected by the voltage detector initially rises from 0 volts to approximately 1.3 volts. Then, in this example, when switch 540 is turned off after approximately 2 seconds, the voltage drops to approximately 1.25 volts. In some cases, drift can be identified when the voltage drops below a fourth threshold. This fourth threshold may be higher than the second threshold discussed above.

[0117] In this example, voltage divider 550, voltage divider 570, voltage detector 560, and voltage detector 580 are used. For example, when the difference between the voltage detected by voltage detector 560 and the voltage detected by voltage detector 580 is higher than a threshold, it can be determined that there is drift on one or more of capacitors 530 or 532.

[0118] A 50% drift in capacitor 530 means that the voltage drop in capacitor 530 is one-third of the total voltage drop, while the voltage drop in capacitor 532 is two-thirds of the total voltage drop. In contrast, without drift, the voltage drops in the capacitors are approximately equal.

[0119] For example, one or more embodiments can be applied to capacitors installed in circuits such as inverters (“main circuit”). One or more embodiments can provide a test circuit that allows the main circuit to operate independently of the test circuit. One or more embodiments can determine whether one or more capacitors have been disconnected from the main circuit or have experienced other faults.

[0120] Other embodiments of this disclosure will be apparent to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. The specification and examples are intended to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

Claims

1. A system comprising: An inverter that converts DC power from a battery into AC power to drive a motor, wherein the inverter includes: A noise filter, comprising a first capacitor connected in series with a second capacitor; and A test circuit configured to test one or more of the first capacitor or the second capacitor, the test circuit comprising: A voltage divider, which includes multiple resistors; A voltage detector configured to measure the voltage at the voltage divider; A switch configured to connect the noise filter to the voltage divider; and One or more controllers are configured to (i) control the operation of the switch to connect the noise filter to the voltage divider, and are configured to (ii) determine, based on the output of the voltage detector, whether one or more of the first capacitor or the second capacitor is connected to the noise filter.

2. The system according to claim 1, wherein the voltage divider and the noise filter are connected to a positive DC voltage source and a negative DC voltage source.

3. The system of claim 1, wherein the plurality of resistors includes a first resistor, a second resistor, a third resistor and a fourth resistor, wherein the first resistor is connected to a positive DC voltage source and the second resistor, wherein the second resistor is connected to the third resistor, and wherein the voltage detector is connected to the third resistor and the fourth resistor.

4. The system of claim 1, wherein the one or more controllers are further configured to: Determine that the measured voltage is higher than a first threshold for a certain period of time; and In response to determining that the measured voltage is higher than the first threshold during the time period, it is determined that the first capacitor and the second capacitor are connected to the noise filter.

5. The system of claim 1, wherein the one or more controllers are further configured to: Determine that the measured voltage is below a second threshold for a certain period of time; and In response to determining that the measured voltage is below the second threshold for a period of time, it is determined that the first capacitor is disconnected from the noise filter.

6. The system of claim 1, wherein the one or more controllers are further configured to: Determining that the measured voltage is higher than a third threshold for a period of time, wherein the third threshold is greater than a first threshold used to determine that the first capacitor is disconnected; and In response to determining that the measured voltage is higher than the third threshold, it is determined that the second capacitor is disconnected from the noise filter.

7. The system of claim 1, wherein the one or more controllers are further configured to: Confirm that the measured voltage is zero volts; and In response to determining that the measured voltage is zero volts, it is determined that the first capacitor and the second capacitor are disconnected from the noise filter.

8. The system of claim 1, wherein the test circuit further comprises: The additional voltage divider includes multiple additional resistors; as well as An additional voltage detector is configured to measure an additional voltage at the additional voltage divider, wherein the one or more controllers are further configured to (iii) determine, based on the output of the voltage detector and the additional output of the additional voltage detector, whether one or more of the first capacitor or the second capacitor is operating at a reduced capacity.

9. The system of claim 8, wherein determining whether one or more of the first capacitor or the second capacitor is operating at a reduced capacitance includes comparing the output with the other output.

10. The system of claim 1, wherein the values ​​of the plurality of resistors are 500KOhm, 500KOhm, 500KOhm and 5KOhm, respectively.

11. The system according to claim 1, further comprising: A battery configured to supply the DC power to the inverter; as well as A motor, configured to receive AC power from the inverter to drive the motor. The system is provided as a vehicle comprising the inverter, the battery, and the motor.

12. A method comprising operating with one or more controllers, the operation including: Connect the first capacitor and the second capacitor of the noise filter to the voltage divider; The voltages at the first capacitor and the second capacitor are measured at a voltage detector connected to the voltage divider. The measured voltage is compared with the threshold voltage; as well as In response to the comparison, it is determined whether one or more of the first capacitor or the second capacitor are connected or disconnected from the noise filter.

13. The method of claim 12, wherein determining whether one or more of the first capacitor or the second capacitor is connected or disconnected from the noise filter comprises determining that the first capacitor and the second capacitor are connected to the noise filter based on a measured voltage greater than the threshold voltage.

14. The method of claim 12, wherein determining whether one or more of the first capacitor or the second capacitor is connected or disconnected from the noise filter includes determining that the first capacitor is disconnected from the noise filter based on a measured voltage being less than the threshold voltage.

15. The method of claim 12, wherein determining whether one or more of the first capacitor or the second capacitor is connected or disconnected from the noise filter comprises determining that the first capacitor and the second capacitor are connected to the noise filter based on a measured voltage of zero volts.

16. A system comprising: A test circuit configured to test one or more capacitors, the test circuit comprising: Voltage divider; A voltage detector is configured to measure the voltage at the first capacitor and the second capacitor as the measured voltage; A switch configured to connect the first capacitor and the second capacitor to the voltage divider; and One or more controllers are configured to (i) control the operation of the switch to connect the first capacitor and the second capacitor to the voltage divider, and are configured to (ii) determine, based on the output of the voltage detector, whether one or more of the first capacitor or the second capacitor is connected to the main circuit.

17. The system of claim 16, wherein the one or more controllers are further configured to: Determine that the measured voltage is higher than a first threshold for a certain period of time; and In response to determining that the measured voltage is higher than the first threshold during the time period, it is determined that the first capacitor and the second capacitor are connected to the main circuit.

18. The system of claim 16, wherein the one or more controllers are further configured to: Determine that the measured voltage is below a second threshold for a certain period of time; and In response to determining that the measured voltage is below the second threshold for a period of time, it is determined that the first capacitor is disconnected from the main circuit.

19. The system of claim 16, wherein the one or more controllers are further configured to: Determining that the measured voltage is higher than a third threshold for a period of time, wherein the third threshold is greater than a first threshold used to determine that the first capacitor is disconnected; and In response to determining that the measured voltage is higher than the third threshold, the second capacitor is disconnected from the main circuit.

20. The system of claim 16, wherein the one or more controllers are further configured to: Confirm that the measured voltage is zero volts; and In response to determining that the measured voltage is zero volts, it is determined that the first capacitor and the second capacitor are disconnected from the main circuit.

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