Driving device for three-phase AC motor, railway vehicle equipped with the driving device, and driving method of three-phase AC motor

Abstract

The invention comprises a load, an inverter device (1) for driving the load, an MCOK_A_4 connected between the inverter device (1) and the load and electrically connecting or disconnecting the inverter device (1) and the load, a voltage detector (21a) having each terminal connected to a circuit of at least two phases in order to detect a three-phase interphase voltage, and a current detector (11) for detecting a phase current of the three phases. In the connection from the inverter device (1) to the load, the inverter device (1), MCOK_A_4, voltage detector (21a), current detector (11), and load are arranged in this order.

Description

Technical Field

[0001] The present invention relates to a driving device for a three-phase AC motor, a railway vehicle equipped with the driving device, and a driving method for the three-phase AC motor. Background Art

[0002] In the driving devices of electric motors for railway vehicles, three-phase AC motors are widely used. In recent years, in order to miniaturize and improve the efficiency of railway vehicle drive systems, permanent magnet synchronous motors (Permanent Magnet Synchronous Motor: hereinafter also abbreviated as "PMSM") are being applied as three-phase AC motors.

[0003] When the PMSM rotates, the permanent magnet flux generates an induced voltage between the terminals of the motor. Therefore, if the inverter device for driving the PMSM continues to operate in a state where a short-circuit fault occurs, the short-circuit current continues to flow through the inverter device due to the induced voltage of the PMSM, and a braking force is generated in the PMSM.

[0004] When such a state occurs even in one inverter device, the acceleration performance of the train will be reduced, and the short-circuit fault current will continue to flow, which may cause equipment to burn out, etc. Therefore, since the train cannot operate normally due to the failure of one inverter device, a motor cutout switch (Motor Cutout Contacts: hereinafter also referred to as "MCOK") is sometimes provided in a PMSM drive device that drives the PMSM to electrically disconnect the PMSM from the inverter device when the inverter device fails.

[0005] In addition, the inverter device that drives a three-phase AC motor such as a PMSM inputs phase current information from a current detector that detects the three-phase phase current and line voltage information from a voltage detector that detects the three-phase phase-to-phase voltage into a control device, and uses the phase current and line voltage information to perform control operations for inverter-driven three-phase AC motors, or uses it as protection detection information to stop the inverter device, etc., to ensure safety, or to prevent device failure. As an example of this structure, patent documents 1 and 2 disclose circuit structure examples that disconnect the PMSM from the inverter device when a device fails. For technologies related to these circuit structure examples, see Patent Documents 1 and 2. Fig. 9 As Comparative Example 1, Fig.10 It will be described at the end as Comparative Example 2.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2011-78254

[0009] Patent Document 2: Japanese Patent Application Publication No. 2013-192300 Summary of the invention

[0010] Problems to be solved by the invention

[0011] The circuit configurations disclosed in Patent Documents 1 and 2 have, for example, the following two problems.

[0012] First, when a short circuit fault occurs between phases of a voltage detector (Alternating Current Potential Transformer: hereinafter also referred to as "ACPT"), when the motor open circuit switch (MCOK) is released (i.e., open circuit), there is a problem that the phase short circuit current of the voltage detector cannot be detected by the current detector. In contrast, in the case of an inverter device and a PMSM motor, especially when the connection with the motor is cut off, it is desirable to detect the regenerative current generated by the motor by an ammeter attached to or built into the inverter device side.

[0013] Second, in the use of railway vehicles, the inverter device is often installed under the floor of the vehicle. In this case, there is the following problem: it is preferred to configure the current detector and ACPT to be installed at the rear end (i.e., close to the motor) compared to the MCOK from the perspective of the inverter device. The reasons are, for example, the following two points. First, due to the size limitations of drive devices such as inverter devices, it is sometimes impossible to install the current detector and ACPT in the inverter device. On the other hand, when the MCOK is installed in the inverter device by post-installation, from the perspective of the installation position of the current detector of the existing inverter device, it is sometimes preferred to configure the current detector and ACPT to be installed at the rear end of the MCOK.

[0014] For example, the above-mentioned problem may arise in order to ensure compatibility and achieve labor saving and simplification between a drive system using an induction motor for a three-phase AC motor and a drive system using a PMSM. In actual railway vehicles, the existing induction motors are being replaced with PMSMs one after another.

[0015] Means for solving problems

[0016] The present invention for solving the above-mentioned problems is a driving device for a three-phase AC motor for driving a load, comprising: an inverter device having a plurality of current control units combining current control elements and rectifying elements, and converting DC power supplied from a power supply into three-phase AC power to drive the load, wherein the current control element conducts or cuts off current flowing in one direction, and the rectifying element is connected in parallel with the current control element and conducts current in a direction opposite to the one direction; a motor opening switch that electrically connects or cuts off the inverter device and the load; a voltage detector that connects each terminal to a circuit of at least two phases in order to detect a phase-to-phase voltage of the three phases; and a current detector that detects the phase current of the three phases, wherein the inverter device, the motor opening switch, the voltage detector, the current detector and the load are arranged in the order of the inverter device, the motor opening switch, the voltage detector, the current detector and the load.

[0017] Effects of the Invention

[0018] The three-phase AC motor drive device of the present invention releases the motor circuit breaker when a short-circuit fault occurs in the voltage detector. The inverter device and the AC motor are electrically disconnected by releasing the motor circuit breaker. Even in such a state, the short-circuit current flowing in the path between the load and the voltage detector can be detected by the current detector.

[0019] As a case where the motor circuit breaker is released, for example, when the load of the three-phase AC motor drive device applied to a railway vehicle is a permanent magnet synchronous motor, in addition to the short-circuit fault of the voltage detector, the output reduction of the inverter device also meets the above situation. In this case, there is also the best safety response by the driver, etc., which is to eliminate the regenerative braking effect of the permanent magnet synchronous motor and continue the operation with other surplus power.

[0020] In addition, when the load is replaced from an induction motor to a permanent magnet synchronous motor, the basic design is to arrange the motor circuit breaker and voltage detector required to avoid the regenerative braking effect generated during the above-mentioned fault in this order near the inverter device. In order to ensure space for the motor circuit breaker, the current detector is arranged near the load to avoid the space. In other words, even if the motor circuit breaker is not required in the inverter device originally designed, if the corresponding space is ensured, there will be no problem in installing it later even if it is needed. That is, regardless of whether there is a motor circuit breaker, it is easy to ensure the interchangeability of the structure and equipment configuration on the inverter device. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1It is a configuration diagram showing an example of a three-phase AC motor drive device (this device) according to an embodiment of the present invention.

[0022] Figure 2 It is a structural diagram showing a modified example of the connection method of the voltage detector.

[0023] Figure 3 (a) is a structural diagram showing an example of an inverter unit structure. Figure 3 (b) is a structural diagram showing another example of the inverter unit structure.

[0024] Figure 4 (a) is a configuration diagram showing a first comparative example of inverter unit configuration. Figure 4 (b) is a structural diagram showing a second comparative example (comparison device 61b) of the inverter unit configuration. Figure 4 (c) is a structural diagram showing the inverter unit configuration of Example 1 (the present device 61c).

[0025] Figure 5 This is a structural diagram of the device of Example 2.

[0026] Figure 6 This is a structural diagram of the device of Example 3.

[0027] Figure 7 This is a structural diagram of the device of Example 4.

[0028] Figure 8 This is a structural diagram of the device of Example 5.

[0029] Fig. 9 It is a configuration diagram of a three-phase AC motor drive device according to Comparative Example 1 (comparative device 7A).

[0030] Fig.10 is a structural diagram of the comparison device 72. DETAILED DESCRIPTION

[0031] Hereinafter, Example 1 as an embodiment of the present invention will be described using the drawings. In the three-phase AC motor drive device, the three-phase AC motor drive device involved in the embodiment of the present invention is simply referred to as the present device, and the three-phase AC motor drive device involved in the comparative example is simply referred to as the comparative device.

[0032] Example 1

[0033] Figure 1 1 is a structural diagram showing an example of the present device 61 of Embodiment 1. The inverter device 1 is composed of a current control element capable of conducting or interrupting a current flowing from a high voltage side to a low voltage side and a diode capable of conducting a current in the opposite direction.

[0034] As a general current control element, a power semiconductor element such as an IGBT (Insulated Gate Bipolar Transistor) or a power MOSFET (Metal Oxide Semiconductor Field Effect) is used.

[0035] Most of these power semiconductor elements use silicon as a material, but in recent years, power semiconductor elements using SiC (silicon carbide) and GaN (gallium nitride) have also increased, which helps to reduce system losses. Therefore, the current control element used in the inverter device 1 of the present invention can also be a current control element using SiC or GaN.

[0036] The inverter device 1 converts DC power output from a DC power source (not shown) into three-phase AC power to drive an AC motor 2. The DC power input to the inverter device 1 connects a smoothing capacitor 3 in parallel with the inverter device 1 at a DC power source input portion of the inverter device, and is connected to a higher-level DC power source via the smoothing capacitor 3. The AC motor 2 is sometimes described as a load.

[0037] The AC motor 2 uses an induction motor or PMSM_2'. Figure 1 2 shows a configuration in which the inverter device 1 drives one AC motor 2, but the inverter device 1 may also drive a plurality of AC motors 2. In the figure, PMSM_2' is distinguished by being denoted by reference numeral 2'.

[0038] ACPT_11a~11c and MCOK_A_4a~4c for detecting the current value of each phase are provided on the AC output side of the inverter device 1. MCOK_A_4a~4c are collectively referred to as MCOK_A_4, and ACPT_11a~11c are collectively referred to as ACPT_11. The control device 31 takes in the detection output of ACPT_11, and operates the switching action of each current control element of the inverter device 1 based on the detection output, so that the AC motor 2 becomes the desired torque output.

[0039] When the current value detected by ACPT_11 becomes abnormally high, the inverter device 1 is stopped to protect equipment and ensure safety, and the release operation of MCOK_A_4 is performed to electrically disconnect the inverter device 1 from the AC motor 2 .

[0040] MCOK_A_4 connects and disconnects the main circuit contacts that electrically connect the inverter device 1 to each of the three phases of the AC motor 2 according to the release command output from the control device 31. In addition, it may be a structure that connects and releases each phase individually, or it may be a structure that connects and releases a plurality of phases in a linked manner.

[0041] In addition, ACPT_11 may be configured to configure ACPT_11a and ACPT_11c for only two phases. That is, it is not necessary to detect the currents of all three phases, and the configuration may be configured to detect any two of the three phases, assume that the three-phase currents are in a balanced state, and calculate the current of the remaining phase.

[0042] On the AC output side of the inverter device 1, an interphase ACPT_21a is also provided on the AC motor 2 side (at Figure 1 In the example, between the U phase and the V phase), the voltage between the phases, that is, the voltage between the terminals of the AC motor, is detected. The control device 31 etc. takes in the detection value of ACPT_21a, and in the case where the AC motor 2 is PMSM_2' etc., the output of the inverter device 1 is controlled after confirming the terminal voltage, thereby being able to stably start the operation as an inverter.

[0043] Here, the connection order of the inverter device 1 , the AC motor 2 , MCOK_A_4 , the current detector 11 , and ACPT_21 a is in the order of the inverter device 1 , MCOK_A_4 , ACPT_21 a , the current detectors 11 a to 11 c , and the AC motor 2 .

[0044] The device 61 is configured as a connection structure as described above. Even when MCOK_A_4 is released and the inverter device 1 and the AC motor 2 are electrically disconnected, when ACPT_21a is short-circuited (in Figure 1 In the case where the U phase and the V phase are short-circuited), the short-circuit current flowing in the path from the AC motor 2 to ACPT_21a can also be detected by the current detectors 11a and 11b.

[0045] In addition, in this device 61, the driver can detect not only the short-circuit fault of ACPT_21a, but also the phase-to-phase short-circuit caused by the burnout of the coil of the AC motor 2 or the wiring or the insulation degradation. This device 61 is suitable for use in applications such as drive devices for railway vehicles. In this application, when such a short-circuit current is detected, even if all MCOK_A_4 are released, the information of the short-circuit current flowing can be sent to the upper device such as the driving console. If the information reaches the driving console, the driver and others can take safe measures based on the information. Specifically, the driving of the corresponding vehicle can be stopped to prevent the damage caused by the equipment failure from expanding.

[0046] Relative to Figure 1 The present device 61, Figure 2 62 is a diagram showing a modified example of the connection method of ACPT_21a. Figure 1 The example in which ACPT_21a is connected between phase U and phase V is shown. Figure 2 As shown in FIG. 1 (control device 31 is not shown), a voltage detector may be connected between two or more phases, such as between the U phase and the V phase (ACPT_21a) and between the added V phase and the W phase (ACPT_21b).

[0047] Figure 3 In order to explain the present device 61 of the first embodiment, the structure diagrams of different inverter units 6 are illustrated. Figure 3 (a) In each phase, only the current detector 11 is inserted (connected), Figure 3 In (b), in addition to inserting (connecting) current detector 11 and MCOK in each phase, ACPT_21a is also provided between phases. Figure 3 (a) shows an example of a unit structure of a general drive device for a railway vehicle, in which a smoothing capacitor 3, an inverter device 1, and a current detector 11 are built into an inverter unit 6 through a housing or the like. In a conventional drive device for a railway vehicle, a three-phase induction motor is used for the AC motor 2, and thus the main components are Figure 3 The portion surrounded by the dotted-line frame in (a) constitutes the inverter unit 6. Insertion means connection with a circuit.

[0048] In recent years, in order to realize the miniaturization and high efficiency of the above-mentioned drive system, there is a railway vehicle using PMSM_2' for the AC motor 2. In this case, Figure 3 As shown in (b) of FIG. 1 , the inverter unit 6 is configured to include a smoothing capacitor 3 , an inverter device 1 , a current detector 11 c , and an ACPT_21 a .

[0049] In particular, in existing vehicles that use an induction motor for the AC motor 2, the AC motor 2 is sometimes replaced with a PMSM_2' while maintaining the housing size and shape of the inverter unit 6 to ensure interchangeability. For example, when the drive device of a railway vehicle is updated, MCOK_A_4 and ACPT_21a are added as built-in devices in the inverter unit 6. In this case, there are the following issues in terms of installation.

[0050] Figure 4 This is a schematic diagram of configuring an inverter unit for a railway vehicle. Figure 4 (a) is a comparative example, Figure 4 (b) is a comparison device 61b after adding MCOK to (a). Figure 4 (c) through Figure 1 , Figure 2 and Figure 3 (b) The device 61 simplifies the drying of clothes. Figure 4 (a) shows an example of an outline of the inverter unit 6 installed in a railway vehicle, and shows an example of the device arrangement inside the conventional inverter unit 6.

[0051] In existing vehicles, such as Figure 4 As shown below (a), due to the limitation of the device installation space in the inverter unit 6, the current detector 11 is sometimes arranged near the external output terminal in the inverter unit 6. As mentioned above, when the AC motor 2 is replaced with PMSM_2', MOCK_4 and voltage detector 21a are added. At this time, if the connection order of the devices is the same as before, Fig.10 The order shown in FIG. 1 is the order of inverter device 1, current detector 11, and MOCK_4. As a result, Figure 4 As shown in the comparison device 61b of (b), the installation inside the inverter unit 6 becomes complicated.

[0052] On the other hand, Figure 1 As in the present device 61 of the first embodiment shown in FIG. 1 , if the order of the inverter device 1, MOCK_4, and the current detector 11 is set, then Figure 4 (c) shows the present device 61c, which can simplify the installation in the inverter unit 6. Thus, in a conventional vehicle using an induction motor for the AC motor 2, when the AC motor 2 is replaced with a PMSM_2' while maintaining the housing size and shape of the inverter unit 6 to maintain interchangeability, the effect of simplification and labor saving can be achieved.

[0053] Example 2

[0054] Next, use Figure 5 Embodiment 2 of the present invention will be described. Figure 5 It is a structural diagram of the device 62 of Example 2. Figure 5 The present device 62 of the second embodiment shown is different from the present device 61 of the first embodiment in that one connection terminal of ACPT_21a is connected between the inverter device 1 and MCOK_A_4a in the U-phase circuit.

[0055] Through this structure, Figure 5The device 62 of the second embodiment shown can cut off the above short-circuit current. In contrast, even if the device 62 is configured to insert one MCOK_A for each of all phases, when a short-circuit fault occurs in ACPT_21a, a short-circuit current flows between ACPT_21a and the AC motor 2. The short-circuit current is detected by the current detectors 11a and 11b and input to the control device 31.

[0056] If the short-circuit current is input to the control device 31, for example, the driver can manually take safety measures at the cab of the train, or the control device 31 can automatically take safety measures. That is, when the short-circuit current becomes equal to or greater than a predetermined current value, the control device 31 controls MCOK_A_4a to 4c (in Figure 5 In particular, the release command is output to 4a and 4b. Figure 5 When 4a and 4b are in particular released, the short-circuit current can be cut off.

[0057] Figure 5 This is merely an example of the structure of the present device 62. That is, one connection point (terminal) of the voltage detector 21 is connected between the inverter device 1 and MCOK_A_4a of the U phase circuit. Also, another connection point (terminal) of ACPT_21a is connected between MCOK_A_4b and the current detector 11b of the V phase circuit.

[0058] In this configuration example, the connection relationship between the U phase and the V phase can be reversed. That is, one connection point of ACPT_21a connected to two of the three phases is connected between the inverter device 1 and MCOK_A, and the other connection point is connected between MCOK_A and the current detector.

[0059] Example 3

[0060] Next, use Figure 6 Embodiment 3 of the present invention will be described. Figure 6 It is a structural diagram of the device 63 of Example 3. Figure 6 The device 63 of the embodiment 3 shown is Figure 5 Compared with the present device 62 of the second embodiment shown, the present device 62 is different in that the first MCOK_A_4b and the second MCOK_B_5b are provided only in the V phase and a two-stage switch structure is formed in series.

[0061] The second MCOK_B_5b is inserted between the connection point of ACPT_21a and the current detector 11b. That is, the connection point on the V-phase side of ACPT_21a is connected to coincide with the connection point of the first MCOK_A_4b and the second MCOK_B_5b.

[0062] Figure 6 The present device 63 of the third embodiment shows an example in which a voltage detector 21b is further provided between the phases V and W. In the present device 63, the connection point on the V phase side of the voltage detector 21b is connected to coincide with the connection point of the first MCOK_A_4b and the second MCOK_B_5b.

[0063] This device 63 can cut off a ground circuit (ie, a ground current). In this device 63 , for example, when a ground occurs on the side of ACPT_21a connected to the V phase, the ground current is detected by the current detector 11b and input to the control device 31 .

[0064] If the ground fault current detected by the control device 31 becomes equal to or greater than a predetermined value, the control device 31 outputs a release command to the second MCOK_B_5b, thereby causing the second MCOK_B_5b to perform a release operation to cut off the ground circuit (ie, the ground fault current).

[0065] Example 4

[0066] Next, use Figure 7 Embodiment 4 of the present invention will be described. Figure 7 This is a structural diagram of the device 64 of Example 4. Figure 7 The device 64 of the fourth embodiment shown is different from the device 61 of the first embodiment in that second MCOK_B_5a~5c are inserted between the current detectors 11a~11c and the AC motor 2, and all three phases U, V, and W are configured as two-stage switches in series.

[0067] In the application Figure 7 In the railway vehicle etc. of the present device 64 of the fourth embodiment shown in FIG. 1 , the effect of continuing the operation by cutting off the short-circuit current is more reliable. Figure 1 , Figure 2 and Figure 3 (b) will be used to compare the present devices 61 and 62 of the first embodiment. In the present devices 61 and 62, when a short-circuit fault occurs in ACPT_21a, a short-circuit current flows between ACPT_21a and the AC motor 2, and the short-circuit current detected by the current detectors 1a and 1b is input to the control device 31.

[0068] If the short-circuit current can be cut off, the railway vehicle etc. to which the device 64 is applied can continue to operate. That is, in the railway vehicle drive device etc., a plurality of identical circuits are formed, so by disconnecting only the drive device in which a fault has occurred, the operation can be continued by the remaining drive devices.

[0069] The control device 31 outputs a release command to the second MCOK_B_5a-5c. Figure 7In the present device 64, the effect of releasing 5a and 5b to cut off the short-circuit current caused by the short-circuit fault of ACPT_21a is particularly good.

[0070] exist Figure 7 In the present device 64, by taking such measures when a fault occurs in ACPT_21a, etc., it is possible to prevent the generation of braking force in the AC motor due to the continuous flow of short-circuit current, which is generated by the regenerative power of ACPT_21a and AC motor 2 (especially when the AC motor is PMSM_2').

[0071] In addition, if Figure 7 As shown, two motor opening switches are provided for each phase, and thus, when the inverter device 1 is started, the first MCOK_A_4 is turned on after the second MCOK_B_5 provided on the AC motor 2 (PMSM_2') side is turned on (closed).

[0072] More specifically, first, the second MCOK_B_5 is turned on, and the phase-to-phase voltage (terminal-to-terminal voltage) of the AC motor 2 is detected by ACPT_21a to estimate the rotor position and speed of the motor.

[0073] Then, based on the estimated position and speed information, the first MCOK_A is turned on in a state where the inverter device 1 is started by the control device 31. This prevents operations such as overcurrent and torque vibration, and enables stable operation as an inverter to be started.

[0074] Example 5

[0075] Figure 8 This is a structural diagram of the device 65 of Example 5. Figure 8 The device 65 of the embodiment 5 shown is Figure 7 The present device 64 of the fourth embodiment shown is different from the present device 65 in the following points: That is, the present device 65 is provided with current detectors 11a to 11c on the side closer to the AC motor 2' with respect to the second MCOK_B_5a to 5c.

[0076] In addition, the device 65 is connected to one side of the two phases of ACPT_21a (in Figure 8 In the U phase side, ACPT_21a is connected between the first MCOK_A_4a and the second MCOK_B_5a. In addition, the device 65 is connected to one phase on the other side (in Figure 8 In the embodiment of the present invention, ACPT_21a is connected between the second MCOK_B_5b and the current detector 11b.

[0077] This structure of the present device 65 can be as Figure 7The device 65 can stably start the operation as an inverter and improve safety as in the present device 64 of the fourth embodiment shown. That is, the present device 65 can prevent the operation such as overcurrent and torque vibration by the order of turning on the first MCOK_A_4a-4c and the second MCOK_B_5a-5c.

[0078] As a result, the inverter can start operating stably. In addition, in the present device 65, the current detectors 11a to 11c are arranged near the AC motor 2 (2'), so that the short-circuit current caused by the short-circuit fault on the AC motor side can be further detected, thereby improving safety.

[0079] The following instructions are Fig. 9 The comparison device 71 and Fig.10 In the comparison device 72, when a fault occurs, the permanent magnet synchronous motor (PMSM_2') 2' performs a regenerative operation. Figures 1 to 8 The AC motor 2 of the devices 61 to 65 shown in the figure is any one of an induction motor or a PMSM_2'. Fig. 9 , Fig.10 In the comparison devices 71 and 72, the description is limited to PMSM_2', so the symbol of the motor is set to 2' for distinction.

[0080] [Comparative Example 1]

[0081] Fig. 9 FIG. 7 is a structural diagram of a three-phase AC motor drive device (comparison device 71) of Comparison Example 1. Fig. 9 The comparison device 71 shown as the comparative example 1 in FIG. 1 has current detectors 11a and 11b and MCOK_A_4a to 4c of different phases inserted in the connection wiring between the inverter device 1 and the PMSM_2'. In addition, the comparison device 71 has ACPT_21a disposed between the phases.

[0082] Regarding the connection order of these devices, between the inverter device 1 and the PMSM_2', the current detectors 11a and 11b are inserted closer to the inverter device 1 and farther from the PMSM_2' with MCOK_A_4a to 4c as the boundary. Therefore, when MCOK_A_4a to 4c are in the released state, the regenerative current of MCOK_B_4 cannot be measured.

[0083] ACPT_21a is arranged on the side close to PMSM_2' with MCOK_A_4a~4c as the boundary. Therefore, when MCOK_A_4a~4c are in the released state, the regenerative voltage of PMSM_2' can be measured, but when ACPT_21a has a short circuit fault, it is difficult to cut off the fault part only by operation from the driver's console. As a result, it is necessary to give up the other healthy power to keep the train running.

[0084] [Comparative Example 2]

[0085] Fig.10 is a structural diagram of the comparison device 72. Fig.10 The comparison device 72 shown as Comparative Example 2 is used in a general DC electric train as a railway vehicle. In the case of a DC electric train, the comparison device 72 is configured to be connected to the DC electric train line on one side and to be connected to a grounded portion such as a wheel on the other side. With respect to the DC electric train line, the DC power supply upper side of the smoothing capacitor 3 is connected to the smoothing reactor 51 via a pantograph 52 as a power collector.

[0086] In addition, there are known structures for obtaining DC power by rectifying AC power from AC overhead wires, or structures for obtaining DC power by a third rail method. Also, structures for obtaining AC power by contactless power transmission and converting it into DC power by a rectifier may be used.

[0087] Fig.10 The comparison device 72 includes current detectors 11a and 11b and MCOK_A_4a to 4c of different phases inserted into the connection wiring between the inverter device 1 and the PMSM_2', and ACPT_21a is provided between the phases.

[0088] Fig.10 The comparison means 72 and Fig. 9 The comparison device 71 of both is similar in that the current detectors 11a and 11b are provided between the inverter device 1 and MCOK_A_4a to 4c or ACPT_21a. Therefore, when MCOK_A_4a to 4c are in the released state, the regenerative current of PMSM_2' cannot be measured by the current detectors 11a and 11b.

[0089] on the other hand, Fig.10 The comparison device 72 and Fig. 9The comparison device 71 of the two has the following differences. That is, the comparison device 72 is a circuit structure in which only one MCOK_A_4b among the three MCOK_A_4a to 4c is inserted between ACPT_21a and PMSM_2'. In addition, with MCOK_A_4b as the boundary, the current detectors 11a and 11b are arranged on the side close to the inverter device 1 and away from PMSM_2'.

[0090] Fig.10 The comparison device 72 of the above circuit structure cannot measure the regenerative voltage and regenerative current of PMSM_2' when MCOK_A_4a~4c are in the released state. However, when ACPT_21a has a short circuit fault, the fault part can be cut off only by operation from the driver's console. As a result, the electric train can continue to operate with other healthy power.

[0091] The present devices 61 to 65 can be summarized as follows. In particular, Figure 1 , 2 , Figure 3 The devices 61 and 62 of the first embodiment shown in (b) are representative examples.

[0092] (1) The present devices 61 and 62 are three-phase AC motor drive devices that drive a three-phase AC motor 2 as a load through an inverter device 1. The inverter device 1 used here has a plurality of current control units, and converts DC power supplied from a power source into three-phase AC power of U, V, and W phases to drive the load.

[0093] The current control unit is a combination of a current control element and a rectifier element. The current control element conducts or cuts off the current flowing in one direction. The rectifier element is connected in parallel with the current control element to conduct the current in the direction opposite to the one direction.

[0094] In the present devices 61 and 62 , a motor opening switch MCOK_A_4 is connected between the inverter device 1 and the load, and the state in which the inverter device 1 and the load are electrically connected or disconnected can be distinguished by the MCOK_A_4 .

[0095] In addition, the three-phase AC power of the U, V, and W phases generated by the inverter device 1 is supplied to the load. In contrast, each terminal of the voltage detector ACPT_21a having a pair of terminals, i.e., two terminals, is connected to at least two phase circuits such as the U phase and the V phase. In order to detect the interphase voltage of the U, V, and W phases, Figure 1 1 ACPT_21a or Figure 2 The two ACPT_21a and 21b shown are sufficient.

[0096] In addition, the current detector 11 for detecting the phase current of the three phases supplied from the inverter device 1 to the load is connected to each of the U, V, and W phases. Here, the circuit configuration from the inverter device 1 to the load is as follows. That is, the connection order of the inverter device 1, the load, MCOK_A_4, the current detector 11, and ACPT_21a is connected in the order of MCOK_A_4 near the inverter device 1, then ACPT_21a, then the current detector 11, and then the load.

[0097] The devices 61 and 62 of such a connection structure have a short circuit fault in ACPT_21a (for example, Figure 1 In the case of a short circuit between the U phase and the V phase of the inverter 1, MCOK_A_4 is released. By releasing MCOK_A_4, the inverter device 1 and the AC motor 2 are electrically disconnected. Even in such a state, the short-circuit current flowing through the path between the AC motor 2 and ACPT_21a can be detected by the current detectors 11a and 11b. This information can be sent to the driver's station in real time. As a result, the driver can easily take the best safety measures.

[0098] As a case where MCOK_A_4 is released, when the load of the present device 61, 62 is PMSM_2', for example, when used in a railway vehicle, in addition to the short-circuit fault of ACPT_21a, the output reduction of the inverter device 1 also meets the above situation. In this case, there is also the best safety response by the driver, etc., which is to eliminate the regenerative braking effect of PMSM_2' and continue the operation with other surplus power.

[0099] The following convenience can also be obtained by the structure of the present devices 61 and 62. That is, if the load originally designed is an induction motor, MCOK is not required because there is no regenerative braking effect and is not provided in the inverter device 1, but the basic design is that MCOK and ACPT_21a required as the load is changed from an induction motor to a PMSM_2' are arranged in this order near the inverter device 1.

[0100] That is, in order to ensure the space for MCOK and ACPT_21a, the current detector 11 is arranged near the load avoiding the space. In other words, even if MCOK and ACPT_21a are not required in the inverter device 1 designed originally, as long as the corresponding space is ensured, there will be no trouble even if they are installed later when they are needed. That is, the interchangeability of the structure and device arrangement in the installation of the inverter device 1 can be easily ensured regardless of whether MCOK and ACPT_21a are present or not.

[0101] (2) Figure 1 , 2 , Figure 3 In the present devices 61 and 62 of the first embodiment shown in (b), MCOK_A_4 is preferably connected between the connection point between the inverter device 1 and the voltage detector ACPT_21a. Thus, the advantages of arranging MCOK_A_4 near the inverter device 1 are as described above.

[0102] (3) Figure 5 In the present device 62 of the second embodiment shown, the connection method of the two-phase circuit connected to ACPT_21a is as follows. In the circuit of one phase (for example, U phase) of the two-phase circuit, MCOK_A_4a is connected between the connection point of ACPT_21a and the current detector 11a. In addition, in the circuit of the other phase (for example, V phase), MCOK_A_4b is connected between the inverter device 1 and the connection point of ACPT_21a.

[0103] Figure 5 The control device 31 shown detects the phase voltage. Even if ACPT_21a fails, the current detectors 11a to 11c are kept capable of detecting the current values ​​of the respective phases. Therefore, it is easy to perform corresponding safety measures.

[0104] (4) Figure 6 In the device 63 of the third embodiment shown, MCOK_A_4b as a first motor opening switch is connected between the connection point of the inverter device 1 and ACPT_21a in the V phase. MCOK_A_5b as a second motor opening switch is connected between the connection point of ACPT_21a and the current detector 11b in the V phase.

[0105] according to Figure 6 In the illustrated embodiment 31, even if a V-phase ground fault occurs due to a ground fault in ACPT_21a, for example, the current detector 11b is kept capable of detecting the V-phase ground fault current, so that corresponding safety measures can be easily taken.

[0106] (5) Figure 7 The device 64 of the fourth embodiment shown includes MCOK_B_5 as a second motor opening switch between the current detector 1 and the load. Thus, MCOK_B_5 as the second motor opening switch forms a two-stage switch in series with MCOK_A_4 as the first motor opening switch.

[0107] Figure 7The control device 31 shown maintains the state in which the current detectors 11a and 11b can detect the regenerative current even if the regenerative braking state is generated due to a short-circuit fault of ACPT_21a in a vehicle equipped with PMSM_2'. At this time, if the control device 31 releases MCOK_B_5, it is easy to take corresponding safety measures.

[0108] In addition, when the inverter device 1 is started, only the second MCOK_B_5 provided on the PMSM_2' side is turned on (closed), and when the phase voltage (terminal voltage) of the PMSM_2' is detected by ACPT_21a, the rotor position and speed of the motor are estimated. Then, based on the estimated position and speed information, the first MCOK_A is turned on in a state where the inverter device 1 is started by the control device 31. In this way, it is possible to prevent actions such as overcurrent and torque vibration, and start the operation as an inverter stably.

[0109] (6) Figure 8 The device 65 of the fifth embodiment shown has a two-stage switch composed of a first MCOK_A_4 and a second MCOK_B_5 connected in series in each phase between the inverter device 1 and the current detectors 11a to 11c. In addition, in the circuit of one U phase of the two phases connected to the voltage detector ACPT_21a, ACPT_21a is connected between the first MCOK_A_4a and the second MCOK_B_5a. In addition, in the circuit of the other V phase, ACPT_21a is connected between the second MCOK_B_5b and the current detector 11b.

[0110] This structure of the device 65 and Figure 7 Compared with the present device 64 of the fourth embodiment shown in FIG. 1 , the operation as an inverter can be started more stably, and the safety is improved. That is, the present device 65 can prevent the operation of overcurrent and torque vibration by the connection sequence of the first MCOK_A_4a~4c and the second MCOK_B_5a~5c. In addition, in the present device 65, the current detectors 11a~11c are arranged near the AC motor 2, so the short-circuit current caused by the short-circuit fault on the AC motor side can be further detected, and the safety is improved.

[0111] Description of Reference Numerals

[0112] 1: inverter device, 2: three-phase AC motor (as load), 2': permanent magnet synchronous motor (PMSM as load), 4, 4a~4c: first motor open-circuit switch (MCOK_A), 5, 5a~5c: second motor open-circuit switch (MCOK_B), 11, 11a~11c: current detector, 21a, 21b: voltage detector (ACPT), 31: control device, 61~65: drive device for three-phase AC motor (this device).

Claims

1. A driving device for a three-phase AC motor driving a load, characterized in that: have: An inverter device having a plurality of current control units combining current control elements and rectifying elements, converting DC power supplied from a power source into three-phase AC power to drive the load, wherein the current control element conducts or cuts off current flowing in one direction, and the rectifying element is connected in parallel with the current control element and conducts current in a direction opposite to the one direction; A motor circuit breaker, which electrically connects or disconnects the inverter device and the load; a voltage detector having each terminal connected to a circuit of at least two phases in order to detect a phase-to-phase voltage of the three phases; and Current detectors, which detect the phase currents of the three phases, In connection from the inverter device to the load, the inverter device, the motor opening switch, the voltage detector, the current detector, and the load are arranged in this order. In one phase of the two-phase circuit connected to the voltage detector, the motor opening switch is connected to a connection point between the voltage detector and the current detector, and in the other phase of the circuit, the motor opening switch is connected to a connection point between the inverter device and the voltage detector. In the phase including the first motor disconnecting switch between the connection point of the inverter device and the voltage detector, a second motor disconnecting switch is connected to the connection point of the voltage detector and the current detector.

2. The three-phase AC motor drive device according to claim 1, characterized in that: The motor opening switch is connected between a connection point between the inverter device and the voltage detector.

3. A driving device for a three-phase AC motor driving a load, characterized in that: have: An inverter device having a plurality of current control units combining current control elements and rectifying elements, converting DC power supplied from a power source into three-phase AC power to drive the load, wherein the current control element conducts or cuts off current flowing in one direction, and the rectifying element is connected in parallel with the current control element and conducts current in a direction opposite to the one direction; A motor circuit breaker, which electrically connects or disconnects the inverter device and the load; a voltage detector having each terminal connected to a circuit of at least two phases in order to detect a phase-to-phase voltage of the three phases; and Current detectors, which detect the phase currents of the three phases, In connection from the inverter device to the load, the inverter device, the motor opening switch, the voltage detector, the current detector, and the load are arranged in this order. Between the inverter device and the current detector, each phase is provided with a two-stage switch connected in series consisting of a first motor opening switch and a second motor opening switch, a circuit of one phase of the two phases connected to the voltage detector is connected between the first motor opening switch and the second motor opening switch, and a circuit of the other phase is connected between the second motor opening switch and the current detector.

4. A railway vehicle, characterized in that: A three-phase AC motor drive device according to any one of claims 1 to 3 is provided.

5. A method for driving a three-phase AC motor, the method comprising: driving the three-phase AC motor as a load by an inverter device, the inverter device converting DC power supplied from a power source into three-phase AC power, It is characterized in that The inverter device has a plurality of current control units that are a combination of current control elements and rectifying elements, wherein the current control elements conduct or cut off current flowing in one direction, and the rectifying elements are connected in parallel with the current control elements and conduct current in a direction opposite to the one direction. In a circuit structure in which the inverter device, the motor circuit breaker, the voltage detector, the current detector, and the load are connected in this order from the inverter device to the load, the voltage detector, each terminal of which is connected to a circuit of at least two phases, detects the phase-to-phase voltage of the three phases. The current detector detects the phase current of the three phases, Based on the detected phase-to-phase voltage or the phase current, the inverter device and the load are electrically connected or disconnected by a motor disconnecting switch connected between the inverter device and the load; In one phase of the two-phase circuit connected to the voltage detector, the motor opening switch is connected to a connection point between the voltage detector and the current detector, and in the other phase of the circuit, the motor opening switch is connected to a connection point between the inverter device and the voltage detector. In the phase including the first motor disconnecting switch between the inverter device and the connection point of the voltage detector, a second motor disconnecting switch is connected to the connection point of the voltage detector and the current detector.

6. The driving method of a three-phase AC motor according to claim 5, characterized in that: The motor disconnecting switch is connected between a connection point between the inverter device and the voltage detector.

7. A method for driving a three-phase AC motor, the method comprising: driving the three-phase AC motor as a load by an inverter device, the inverter device converting DC power supplied from a power source into three-phase AC power, It is characterized in that The inverter device has a plurality of current control units that are a combination of current control elements and rectifying elements, wherein the current control elements conduct or cut off current flowing in one direction, and the rectifying elements are connected in parallel with the current control elements and conduct current in a direction opposite to the one direction. In a circuit structure in which the inverter device, the motor circuit breaker, the voltage detector, the current detector, and the load are connected in this order from the inverter device to the load, the voltage detector, each terminal of which is connected to a circuit of at least two phases, detects the phase-to-phase voltage of the three phases. The current detector detects the phase current of the three phases, Based on the detected phase-to-phase voltage or the phase current, the inverter device and the load are electrically connected or disconnected by a motor disconnecting switch connected between the inverter device and the load; Between the inverter device and the current detector, a two-stage series switch consisting of a first motor opening switch and a second motor opening switch is provided in each phase, a circuit of one phase of the two phases connected to the voltage detector is connected between the first motor opening switch and the second motor opening switch, and a circuit of the other phase is connected between the second motor opening switch and the current detector.

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