Drive systems, vehicles and methods

Abstract

This device detects short-circuit faults between the contactor and the drive motor. [Solution] A drive system comprising a main power supply 03, a converter 04 configured to receive power from the main power supply and provide a multiphase drive current, and a plurality of permanent magnet motors configured to receive the multiphase drive current, further comprising one or more contactors 06a, 06b disposed between the converter and the permanent magnet motors and configured to selectively isolate the permanent magnet motors from the converter, and a controller 05 comprising voltage sensors 07a, 07b located between the contactors and the permanent magnet motors and configured to sense the voltage between one or more positions of the multiphase drive current, and configured to detect a short-circuit fault of the permanent magnet motors based on one or more sensed voltages from the voltage sensors while the one or more contactors are open.

Description

Technical Field

[0001] The present disclosure relates to a drive system, a vehicle, and a method.

Background Art

[0002] The traction motor is used in variable speed drive systems such as electric vehicles and railway vehicles (e.g., locomotives). Mainly, these traction motors are implemented as either induction motors or synchronous motors. Conventionally, induction motors have been used. However, in order to further improve efficiency and reduce energy consumption, synchronous motors, particularly permanent magnet synchronous motors (PMSMs), have also been introduced.

[0003] Since a PMSM includes permanent magnets, an induced voltage is generated during rotation. Therefore, a contactor is implemented in the circuit to electrically isolate the motor when necessary to protect the components from this induced voltage.

[0004] However, the inventors have identified a problem that when a short circuit occurs downstream of the contactor (i.e., between the contactor and the traction motor), a short-circuit current continues to flow because the motor generates an induced voltage even when the contactor is open.

[0005] The present disclosure has been made in view of the above considerations.

Summary of the Invention

[0006] Thus, in a first aspect, embodiments of the present invention provide a drive system, the drive system comprising: a main power supply; a converter configured to receive power from the main power supply and provide a polyphase drive current; a permanent magnet motor configured to receive the polyphase drive current; one or more contactors arranged between the converter and the permanent magnet motor and configured to selectively isolate the permanent magnet motor from the converter; A voltage sensor configured to sense the voltage between one or more positions of the multiphase drive current at a position between the one or more contactors and the permanent magnet motor, The system includes a controller configured to receive a sensing voltage from the voltage sensor and to detect a short-circuit fault of the permanent magnet motor based on the received sensing voltage while one or more contactors are open.

[0007] Such a drive system can detect a short-circuit fault in a permanent magnet motor even when the contactor is open.

[0008] The controller may be configured to detect the short-circuit fault by comparing the waveform of the sensed voltage received for each of the aforementioned or relative positions with a predetermined normal waveform. The predetermined normal waveform may be a waveform that can be observed when no short-circuit fault occurs between the aforementioned or relative positions, and may be stored in the controller's memory. Comparing the waveforms of the sensed voltage received for each of the aforementioned or relative positions may include calculating the distortion rate of each waveform and comparing the said distortion rate with a threshold corresponding to the predetermined normal waveform. Any calculation method can be applied as long as it is a calculation method that can be used to determine how much the shape of the waveform at the sensed voltage differs from the shape of a predetermined normal waveform (e.g., distortion rate). The said distortion rate may be calculated using the following formula.

number

[0009] Here, THD (Total Harmonic Distortion) represents the distortion rate, V1 is the fundamental frequency coefficient of the voltage, and V k V1 is the kth-order coefficient of the voltage (k≧2) (e.g., the effective voltage of harmonic components that are integer multiples of the fundamental frequency). For example, if a motor is driven at 50Hz, this forms the fundamental frequency. If there is a short-circuit fault, term V1 is expected to decrease for the corresponding phase, and therefore the THD will increase. In contrast, if the waveform is a normal waveform, the THD value will be low. Term V kThese coefficients (from 1 to the kth order coefficient, for example, the 30th order) may be derived by applying a Fast Fourier Transform to the measured voltage. In some cases, THD exceeding 10% may indicate an abnormal waveform and thus a short-circuit fault.

[0010] The distortion rate may be calculated for each relative position, and then, in order to determine whether there is a short-circuit fault between those relative positions, the calculated distortion rates are compared to a predetermined threshold, such as 10%.

[0011] The drive system may include a plurality of permanent magnet motors, each permanent magnet motor isolated from the converter by one or more contactors. The contactors may be shared among the plurality of permanent magnet motors, or each permanent magnet motor may have its own contactor. In such a drive system, there may be one voltage sensor for each permanent magnet motor, i.e., a plurality of voltage sensors, so configured to sense the voltage between one or more pairs of multilayer drive currents at a position between one or more contactors and each permanent magnet motor. Accordingly, the controller may receive the sensed voltage(s) from each of the plurality of voltage sensors and detect each short-circuit fault in each of the plurality of permanent magnet motors.

[0012] The drive system may further include a temperature sensor configured to sense the temperature of a permanent magnet motor, and the controller may be configured to receive the sensed temperature from the temperature sensor and to detect or verify a short-circuit fault in the permanent magnet motor based on the sensed temperature. The controller may be configured to detect or verify a short-circuit fault in the permanent magnet motor by deriving a rate of temperature change over time and comparing said rate of temperature change to a predetermined ratio indicating the absence of any short-circuit faults.

[0013] The controller may further be configured to detect the motor rotor position and / or rotor speed based on the received sensing voltage(s). For example, the received sensing voltage may be divided into dq coordinates (generally referred to as dq coordinate transformation). The controller may further be configured to monitor the motor current and thus calculate each d / q axis induced voltage using the current, monitored impedance, and inductance values ​​(which are known in advance and stored in the controller). The controller can then compare the predicted dq voltage with the received sensing voltage and use the phase gap to detect the rotor position and / or speed.

[0014] The controller may be configured to repeatedly receive one or more sensing voltages from a voltage sensor and to detect whether a short-circuit fault is detected from each received sensing voltage. The controller may be directly connected to the voltage sensor and may continuously receive sensing voltages if the voltage sensor provides an analog signal. This detection may be performed periodically, for example, at a rate of 100 Hz (or every 10 milliseconds).

[0015] The controller further states that while one or more contactors are closed, The system receives the sensed voltage (one or more) from the voltage sensor and detects a short-circuit fault based on the received sensed voltage. In response to the detection of the short-circuit fault while the contactor is closed, one or more contactors are opened, and After one or more of the contactors have opened, an attempt is made to re-detect the short-circuit fault, and In response to the re-detection of the aforementioned short-circuit fault, it is detected that the permanent magnet motor has the aforementioned short-circuit fault, or In response to the inability to re-detect the aforementioned short-circuit fault, the controller may be configured to detect the presence of the short-circuit fault between the converter and one or more contactors. In response to the determination that the presence of the short-circuit fault between the converter and one or more contactors, the controller may be configured to disconnect the main power supply from the power source. For example, if the drive system is incorporated into a train, the controller may disconnect the main transformer (which provides the main power supply) from the overhead catenary (which provides the power supply) by lowering the pantograph.

[0016] The controller may be configured to issue an alert when a short-circuit fault is detected. This alert may be directed to a driver assistance system, such as a driver console in a railway vehicle.

[0017] The converter may be configured to provide three-phase drive currents such as V, U, and W phases, the voltage sensor may be configured to sense the relative voltages between each of the three-phase drive currents, and one or more contactors may be three-phase contactors configured to operate simultaneously on all three phases. The sensing may be direct or indirect. For example, the voltage sensor may directly sense the VU, VW, and UW voltages. Alternatively, the sensing may be at least partially indirect. For example, the voltage sensor may directly sense the VU and VW voltages and infer the UW voltage from them. This inferred voltage can be obtained by subtracting the absolute value of one of the measured voltages from the absolute value of the other of the measured voltages (e.g., |UW| = |VU| - |VW|).

[0018] In a second aspect, embodiments of the present invention provide a vehicle comprising the drive system of the first aspect and, optionally, any one or any combination thereof, insofar as it is compatible with the optional features of the first aspect.

[0019] The vehicle may further include wheels, a mechanical brake, and a brake controller. The brake controller is configured to operate the mechanical brake to apply braking force to the vehicle based on a signal received from the controller when the short-circuit fault is detected. The braking force applicable by the mechanical brake may be independent of the permanent magnet motor, such as an air brake.

[0020] The vehicle may be a railway vehicle. The railway vehicle may form part of a train and may be a locomotive. The vehicle may be an automobile (such as an electric vehicle, bus, or truck) having a drive system consisting of a permanent magnet motor for driving.

[0021] In a third aspect, an embodiment of the present invention provides a method for detecting a short-circuit fault in a permanent magnet motor for a drive system, the method comprising: Receiving a sensed voltage between one or more phases of a polyphase drive current at a position between one or more contactors and the permanent magnet motor, the contactor(s) being between a converter and the permanent magnet motor, and the converter receiving power from a main power source and providing the polyphase drive current, Detecting a short-circuit fault of the permanent magnet motor from the sensed voltage(s) while the one or more contactors are open.

[0022] The method may be computer-implemented and may be performed by a controller (e.g., the controller of the first aspect). The method may be repeated to repeatedly receive the sensed voltage(s) from a voltage sensor and detect whether a short-circuit fault is detected from each received sensed voltage. When directly connected to the voltage sensor and the voltage sensor provides an analog signal, the sensed voltage may be continuously received. This detection may be performed periodically, for example, at a rate of 100 Hz (or every 10 milliseconds).

[0023] The method described above may be carried out using or on a drive system of the first embodiment and optionally includes any one or any combination thereof, insofar as it is compatible with the optional functions described by reference thereto.

[0024] In a fourth aspect, an embodiment of the present invention provides a drive system comprising: a main power supply; a converter configured to receive power from the main power supply and to provide a multiphase drive current; a permanent magnet motor configured to receive the multiphase drive current; one or more contactors disposed between the converter and the permanent magnet motor and configured to selectively isolate the permanent magnet motor from the converter; a temperature sensor configured to sense the temperature of the permanent magnet motor; and a controller configured to receive the sensed temperature and to detect a short-circuit fault of the permanent magnet motor based on the received sensed temperature.

[0025] The controller may be configured to detect or verify the short-circuit failure of the permanent magnet motor by deriving the rate of temperature change over time and comparing the rate of temperature change with respect to health values.

[0026] A drive system of the fourth embodiment may further include a voltage sensor configured to sense the voltage between one or more positions of the multiphase drive current at a position between one or more contactors and the permanent magnet motor.

[0027] A controller in a fourth embodiment may be configured to receive the sensed voltage(s) from the voltage sensor, detect the presence of a short-circuit fault in the permanent magnet motor based on the sensed temperature, and then further detect or verify the short-circuit fault based on the received sensed voltage(s). This further detection or verification may include identifying which phase of the multilayer drive current is short-circuited.

[0028] In a fifth aspect, an embodiment of the present invention provides a method for detecting a short-circuit fault in a permanent magnet motor, the method comprising receiving a sensing temperature of the permanent magnet motor and detecting a short-circuit fault in the permanent magnet motor from the sensing temperature.

[0029] The present invention includes combinations of the described embodiments and preferred features, except where such combinations are clearly unacceptable or expressly avoidable. For example, a controller of the fourth embodiment may be configured to detect a short-circuit fault based on a received sensing voltage(s) using any of the features described with reference to the controller of the first embodiment.

[0030] A further aspect of the present invention provides a computer program that, when running on a computer, causes the computer to perform the method of the third or fourth aspect; a computer-readable medium that stores the computer program that, when running on the computer, causes the computer to perform the method of the third or fourth aspect; and a computer system programmed to perform the method of the third or fifth aspect. [Brief explanation of the drawing]

[0031] [Figure 1] This indicates a vehicle including its drive system. [Figure 2] This shows a partial drive system. [Figure 3] The graph shows a plot of voltage against time. [Figure 4] Figure 2 shows the partial drive system in a UV short-circuit state. [Figure 5] The sensed voltage for the state shown in Figure 4 is indicated. [Figure 6] Figure 2 shows the partial drive system in a VW short-circuit state. [Figure 7] The sensed voltage for the state shown in Figure 6 is indicated. [Figure 8] Figure 2 shows the partial drive system in a UW short-circuit state. [Figure 9]The sensed voltage for the state shown in Figure 8 is indicated. [Figure 10] A flowchart is shown. [Figure 11] This shows a deformation-part drive system. [Figure 12] The graph shows a plot of temperature against time. [Figure 13] Figure 11 shows the deformation part drive system in a UV short-circuit state. [Figure 14] Figure 13 shows a plot of temperature against time in the UV short-circuit state. [Figure 15] A flowchart is shown. [Modes for carrying out the invention]

[0032] Aspects and embodiments of the present invention will be described below with reference to the accompanying drawings. Further aspects and embodiments will be apparent to those skilled in the art.

[0033] Figure 1 shows a vehicle 12, which is a railway vehicle moving on a track 13 in this embodiment, and the vehicle 12 includes a drive system 100 consisting of traction functions or components for converting electrical power into mechanical power or kinetic energy. In this embodiment, the railway vehicle uses a pantograph 02 to obtain power from an overhead catenary 01, but in other examples, power may be obtained from an onboard energy storage system (e.g., a battery or capacitor) or generated using a generator (e.g., a diesel generator set). The received power is supplied to high-voltage equipment 03. In examples where the railway vehicle is driven by a catenary, the high-voltage equipment may include a high-speed circuit breaker (if the catenary provides DC) or a vacuum circuit breaker and a main transformer (if the catenary provides AC).

[0034] This main power is then supplied to a traction converter unit 04, such as an inverter (if the main power is AC power). In some examples, the traction converter unit may include an AC / AC converter or a DC / AC converter. Included as part of the traction converter unit 04 is a control logic unit 05 (also called a controller) that controls the operation of the traction converter unit. The traction converter unit supplies a multiphase output current to (four in this embodiment) PMSMs (permanent magnet synchronous motors) 08a-08d. These motors use the drive current to rotate their respective wheels 10a-10d located on one or more bogies 11a, 11b. These wheels may include mechanical brakes, such as pneumatic brakes (not shown), which can apply braking force to the wheels according to signals from a brake controller (not shown). The brake controller is configured to operate the mechanical brakes through the control logic unit and a train system (not shown) connectable to the brake controller. Between the PMSMs and the traction converter unit are contactor boxes 06a and 06b, which include several contactors for selectively isolating the PMSMs from the traction converter unit. In this embodiment, one contactor box includes contactors for two PMSMs.

[0035] The drive system also includes voltage sensors 07a, 07b (where ACPT represents an AC instrument transformer). These voltage sensors are configured to sense the voltage of a multiphase drive current (such as a three-phase current consisting of U, V, and W phases) provided by the traction converter unit 04 at a position between the contactor assembly and each PMSM. For example, voltage sensor 07b is positioned between contactors located between the contactor box 06b and PMSMs 08c and 08d. In this embodiment, each voltage sensor is configured to sense the voltage of two of the three relative positions (UV and VW). These sensed voltages are provided to the control logic unit 05. The drive system also includes temperature sensors 09a to 09d, each positioned near each PMSM 08, and thus capable of sensing the temperature of each PMSM 08.

[0036] Figure 2 shows a partial drive system. This partial drive system includes a traction converter unit 04 and a PMSM 08a connected to the traction converter unit via three contactors in a contactor box 06a. Here, since the drive current is three-phase, three contactors or simply a three-phase contactor capable of operating all three phases simultaneously are provided. These phases are conventionally represented as U, V, and W. The voltage sensor consists of two components: 07a-1, which senses the voltage between the U and V phases, and 07a-2, which senses the voltage between the V and W phases. These sensed voltages are provided to the control logic unit 05, which can then estimate the UW phase voltages as described above. Figure 3 shows a plot of voltage against time, showing normal waveforms for each of the three phases that can be observed when no short-circuit faults occur between each relative point. As expected, the voltages for the UV phase (Vuv), WU phase (Vwu), and VW phase (Vvw) are sinusoidal and 90 degrees out of phase with each other. After the contactor opens, this voltage is generated by the rotating motor via an induced voltage.

[0037] Figure 4 shows the partial drive system of Figure 2 in a UV short-circuit condition. This is indicated by the black dots and links between the U and V phases between contactor box 06a and PMSM08a. Figure 5 shows the sensing voltages for the condition in Figure 4. In particular, the VU voltages are zero or nearly zero due to the short-circuit fault, and the VW and WU waveforms are significantly different from normal waveforms (e.g., they no longer cross the x-axis).

[0038] Figure 6 shows the partial drive system of Figure 2 in a VW short-circuit condition. This is indicated by the black dots and links between the V and W phases between contactor box 06a and PMSM08a. Figure 7 shows the sensing voltage for the condition in Figure 6. The VW voltage is zero or nearly zero due to the short-circuit fault, and the UV and WU waveforms are significantly different from normal waveforms (e.g., they no longer cross the x-axis).

[0039] Figure 8 shows the partial drive system of Figure 2 in a WU short-circuit condition. This is indicated by the black dots and links between the U and W phases between the contactor box 07a and PMSM08a. Figure 9 shows the sensing voltage for the condition in Figure 8. The WU voltage is zero or nearly zero due to the short-circuit fault, and the UV and VW waveforms are significantly different from normal waveforms (e.g., they no longer cross the x-axis).

[0040] Figure 10 shows a flowchart of a method for detecting or verifying a short-circuit fault in a PMSM. In the first and optional step S102, a contactor between a given PMSM and the traction converter is opened to isolate the motor from the power supply. Subsequently, the control logic unit calculates the THD[%] in step S104. This calculation is performed by performing a Fast Fourier Transform on the relative sensing voltages (e.g., UV, VW, or WU). The THD[%] is then calculated using the following formula.

number

[0041] Here, THD[%] is the aforementioned distortion rate, V1 is the fundamental frequency coefficient of the voltage, and V kis the k-th coefficient of the voltage. A THD of 5% can be considered to indicate that no short-circuit faults have occurred between each relative point, and a THD of 10% can be considered to indicate that a short-circuit fault has occurred. Therefore, in step S106, the calculated THD[%] can be compared to a predetermined threshold. Applying 5% as the predetermined threshold allows the control logic unit to detect more likely short-circuit faults, while applying 10% allows the control logic unit to focus on a higher probability of a short-circuit fault in the PMSM. If the calculated THD[%] is not higher than the predetermined threshold ("No"), the method proceeds to step S108, where it is determined that the waveform for this relative point is normal (i.e., there are no short-circuit faults). However, if the calculated THD[%] is higher than the predetermined threshold ("Yes"), the method proceeds to step S110, where it is detected or verified that there may be a short-circuit fault on the PMSM side of the contactor. As a result, a short-circuit warning alarm is issued in step S112.

[0042] Steps S104-S108 / S112 may be repeated for each position of the multiphase drive current so that not only can the short circuit itself be identified, but also which position of the multiphase drive current is affected. Steps 104 (optionally including step S102 first)-S108 / S112 may be triggered depending on whether a short-circuit fault exists on the PMSM side of the contactor, as determined according to the method in Figure 15. For example, a temperature-based method may determine the likelihood of a short-circuit fault itself, after which the method in Figure 10 may be used to (i) detect the presence of the fault and / or (ii) detect which position of the multiphase drive current is short-circuited. The entire method may be repeated periodically throughout the use of the train, and may be triggered in particular after the contactor has opened.

[0043] The method shown in Figure 10 may be initiated by an initial determination made while the contactor is closed. In this embodiment, the same steps S104-S106 may be performed while the contactor is closed (i.e., a short circuit may be detected). In response to this detection, the contactor is then opened. Steps S104-S106 are then performed again, and if a short circuit is detected again, the control logic unit reports that a short circuit has been found in the PMSM of the contactor. However, if a short circuit is not detected again, it reports that a short circuit has been found on the other side of the contactor, i.e., between the traction converter section and one or more contactors. If a short circuit is detected on the other side of the contactor, the control logic unit may disconnect converter 04 so that converter 04 stops supplying power to the short-circuit fault location.

[0044] Figure 11 shows a deformable partial drive system. This deformable partial drive system includes a traction converter unit 04 and one PMSM 08a connected to the traction converter unit via three contactors in a contactor box 06a. Here, since the drive current is three-phase, three contactors are provided. These phases are conventionally represented as U, V, and W. Here, a temperature sensor 09a is provided in or near the PMSM to sense the temperature of the PMSM and transmit the sensed temperature to the control logic unit 05. Figure 12 shows a plot of temperature against time under normal conditions, and when the motor is operating, the temperature gradually rises to a stable state and maintains that stable state during operation, which can be observed when there are no short-circuit faults in the PMSM.

[0045] Figure 13 shows the deformed partial drive system of Figure 11 in a UV short-circuit state. This is indicated by the black circles and links between the U and V phases between the contactor box 06a and PMSM08a. Figure 14 shows a plot of temperature against time during the UV short-circuit state in Figure 13. The initial behavior is the same as in the normal state, and in this state, once the motor starts operating, a gradual increase in temperature is observed. This gradual increase is the motor temperature fluctuation rate dT, which can be observed in the normal state when no short-circuit faults occur in the PMSM. emp Provides / dt (or a known health value may be stored in advance). However, after a short-circuit fault occurs (indicated by the arrow), the temperature rises more rapidly. The motor temperature fluctuation rate after this is the same as the motor temperature fluctuation rate dT in a normal state. emp The value is higher than / dt and indicates a short circuit. After rising, the temperature flattens out again, but remains higher than in normal conditions (for example, due to saturation of the temperature sensor / PMSM).

[0046] Figure 15 shows a flowchart of a method for detecting or verifying a short-circuit fault in a PMSM. In the first step S202, the calculated motor temperature fluctuation rate (dT emp The motor temperature fluctuation rate ( / dt) is compared with a predetermined motor temperature fluctuation rate that indicates the absence of any short-circuit faults. If the calculated motor temperature fluctuation rate is the same as or lower than the predetermined motor temperature fluctuation rate ("Yes"), the method proceeds to step S204, where it is determined that the PMSM is normal (meaning that there are no short-circuit faults). However, if the calculated motor temperature fluctuation rate is higher than the predetermined motor temperature fluctuation rate ("No"), the method proceeds to step S206, where it is detected or verified that there may be a short-circuit fault on the PMSM side of the contactor. As a result, a short-circuit warning alarm is issued in step S208.

[0047] The method shown in Figure 15 may be invoked in response to a determination that there may be a short-circuit fault on the PMSM side of the contactor, according to the method shown in Figure 10. For example, the voltage-based method may be used to determine the possibility of a short-circuit fault (and to identify the relatives suspected of being short-circuited), and then the method shown in Figure 15 may be used to verify the presence of the fault.

[0048] The systems and methods of the above embodiments may be implemented in computer systems (particularly in computer hardware or computer software) in addition to the structural components or user interactions described.

[0049] The term "computer system" includes hardware, software, and data storage devices for implementing a system according to the above embodiments or for carrying out methods according to the above embodiments. For example, a computer system may include a central processing unit (CPU), input means, output means, and data storage. A computer system may have a monitor for providing a visual output display. Data storage may include RAM, disk drives, or other computer-readable media. A computer system may include a plurality of computing devices connected by a network and capable of communicating with each other over the network.

[0050] The methods of the above embodiments may be provided as a computer program deployed when operating on a computer to perform the above methods (one or more), or as a computer program product or computer-readable medium carrying the computer program.

[0051] The term “computer-readable medium” includes, but is not limited to, any non-temporary medium that can be read and directly accessed by a computer or computer system. Such medium may include, but is not limited to, magnetic storage mediums such as floppy disks, hard disk storage media and magnetic tape; optical storage mediums such as optical disks or CD-ROMs; electrical storage mediums such as RAM, ROM and flash memory; and hybrids and combinations of the above mediums such as magnetic / optical storage mediums.

[0052] While the present disclosure has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art. Therefore, the exemplary embodiments of the present disclosure described above are illustrative and not limiting. The embodiments described may be modified in various ways without departing from the spirit and scope of the present disclosure.

[0053] In particular, although the methods of the above embodiments have been described as being implemented on the systems of the embodiments described, the methods and systems of this disclosure do not need to be implemented in conjunction with each other and can each be implemented on alternative systems or using alternative methods.

[0054] Features disclosed herein or in the following claims or accompanying drawings, which are expressed in particular forms therein, or in relation to means for performing the disclosed functions, or methods or processes for obtaining the disclosed results (if applicable), may be used individually or in any combination of such features to implement the present disclosure in various forms.

[0055] While this disclosure has been described in relation to the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art. Therefore, the exemplary embodiments of the above disclosure are considered illustrative and not limiting. The embodiments described may be modified in various ways without departing from the spirit and scope of this disclosure.

[0056] To avoid any doubt, the theoretical explanations provided herein are provided for the purpose of improving the reader's understanding. The inventors do not wish to be bound by any of these theoretical explanations.

[0057] The section headings used in this specification are for structural purposes only and should not be construed as limiting the subject matter described herein.

[0058] Throughout this Specification (including the claims that follow), unless the context requires otherwise, the words “comprise” and “include,” as well as variations such as “comprises,” “comprising,” and “including,” are understood to imply that they encompass one integer or step, or a group of integers or steps, as described, but not that they exclude any other integer or step, or a group of integers or steps.

[0059] As used herein and in the appended claims, the singular forms “a,” “an,” and “the” refer to multiple objects unless the context explicitly indicates otherwise. In this specification, ranges may be expressed as “about” a particular value and / or “about” another particular value. Where such ranges are expressed, other embodiments include the one particular value and / or the other particular value. Similarly, where values ​​are expressed as approximations, the use of the preceding word “about” will be understood to mean that a particular value forms another embodiment. “About,” as a numerical term, is optional and can mean, for example, + / - 10%.

Claims

1. A drive system (100), Main power supply (03), A converter (04) configured to receive power from the main power supply and to provide multiphase drive current, A permanent magnet motor (08a, 08b, 08c, 08d) configured to receive the multiphase drive current, One or more contactors (06a, 06b) are disposed between the converter and the permanent magnet motor and configured to selectively isolate the permanent magnet motor from the converter, A voltage sensor (07a, 07b) configured to sense the voltage between one or more positions of the multiphase drive current at a position between the one or more contactors and the permanent magnet motor, While one or more of the contactors are open, the system is configured to receive a sensing voltage from the voltage sensor and to detect a short-circuit fault in the permanent magnet motor based on the received sensing voltage, and while one or more of the contactors are closed, The system receives the sensed voltage (one or more) from the voltage sensor and detects a short-circuit fault based on the received sensed voltage. In response to the detection of the short-circuit fault while the contactor is closed, one or more contactors are opened. After one or more of the contactors have opened, an attempt is made to re-detect the short-circuit fault, and In response to the re-detection of the aforementioned short-circuit fault, it is detected that the permanent magnet motor has the aforementioned short-circuit fault, or In response to the inability to re-detect the aforementioned short-circuit fault, the system detects that the short-circuit fault exists between the converter and one or more contactors. A controller (05) configured as follows and A drive system (100) comprising the above.

2. The drive system according to claim 1, wherein the controller is configured to detect a short-circuit fault by comparing the waveform of the sensed voltage received for the aforementioned or relative to each point with a predetermined normal waveform that can be observed when no short-circuit fault occurs between the aforementioned or relative to each point.

3. The drive system according to claim 2, wherein comparing the waveforms of the sensed voltage received for the aforementioned or relative to each point includes calculating the distortion rate of each waveform and comparing the said distortion rate with a threshold corresponding to a predetermined normal waveform.

4. The aforementioned distortion rate is calculated using the following formula: Here, THD, or total harmonic distortion, is the aforementioned distortion rate, V １ V is the fundamental frequency coefficient of the voltage, ｋ The drive system according to claim 3, wherein is the kth coefficient of the voltage.

5. A drive system further comprising a temperature sensor configured to sense the temperature of the permanent magnet motor, wherein the controller is configured to receive the sensed temperature from the temperature sensor and to detect or verify a short-circuit failure of the permanent magnet motor based on the received sensed temperature, according to claim 1.

6. The drive system according to claim 5, wherein the controller is configured to detect or verify the short-circuit failure of the permanent magnet motor by deriving the rate of temperature change with respect to time and comparing the rate of temperature change with a predetermined ratio indicating that there are no short-circuit failures whatsoever.

7. The drive system according to claim 1, wherein the controller is further configured to detect the motor rotor position and / or rotor speed based on the received sensing voltage.

8. The drive system according to claim 1, wherein the controller is configured to disconnect the main power supply from the power source in response to the detection of the presence of the short-circuit fault between the converter and the one or more contactors.

9. The drive system according to claim 1, wherein the controller is configured to issue an alert when it detects the short-circuit fault.

10. The drive system according to claim 1, wherein the converter is configured to provide a three-phase drive current, and the voltage sensor is configured to sense the voltage between each of the three-phase drive currents.

11. A vehicle comprising the drive system according to any one of claims 1 to 10.

12. A vehicle further comprising wheels, a mechanical brake, and a brake controller, wherein the brake controller is configured to activate the mechanical brake to apply braking force to the vehicle based on a signal from the controller when it detects the short-circuit fault, according to claim 11.

13. The vehicle according to claim 11, wherein the vehicle is a railway vehicle.

14. A method for detecting a short-circuit fault in a permanent magnet motor for a drive system, The system receives a sensing voltage between one or more positions of the multiphase drive current at a position between one or more contactors and the permanent magnet motor, The contactor(s)(s)(s)(s)(s)(s)(s)(s))))))) While one or more of the contactors are open, a short-circuit fault in the permanent magnet motor is detected from the sensed voltage (one or more), While one or more contactors are closed, the system receives the sensed voltage (one or more) from the voltage sensor and detects a short-circuit fault based on the received sensed voltage. In response to detecting the short-circuit fault while the contactor is closed, one or more contactors are opened. After one or more of the contactors have opened, an attempt is made to re-detect the short-circuit fault, and In response to the re-detection of the aforementioned short-circuit fault, it is detected that the aforementioned short-circuit fault exists in the permanent magnet motor, or In response to the inability to re-detect the aforementioned short-circuit fault, it is detected that the short-circuit fault exists between the converter and one or more contactors. Methods that include...

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