Power conversion device for an electric vehicle

Abstract

Power conversion device (1) for an electric vehicle, comprising: an inverter (2) for driving a motor (55) installed in an electric vehicle; and a controller (3) for controlling the inverter (2) based on an operating command, where the control (3) a sensorless control unit (30) and corrects an initial resistance value set in the controller (3), based on temperature information from a temperature sensor (5a) provided in the power conversion device (1) or from temperature information transmitted from outside the power conversion device (1), sets a resistance value of the motor (55) to the corrected initial resistance value and causes the sensorless control unit (30) to operate based on the set resistance value of the motor (55), wherein the control (3) has: a resistance estimation unit (33) for calculating a resistance estimate value, which is an estimate of the resistance value of the motor (55), using a current flowing to the motor (55); a resistance value setting unit (34) to maintain the corrected initial resistance value, to output the initial resistance value to the sensorless control unit (30) until the resistance estimate is received from the resistance estimation unit (33), and to output the resistance estimate to the sensorless control unit (30) after the resistance estimate has been received from the resistance estimation unit (33); and a resistance estimation execution determination unit (31) to generate a flag (Flg1) to perform the resistance estimation when the operating command (PB) is received as input, and to supply the flag to the resistance estimation unit (33) and the resistance value setting unit (34), wherein the resistance estimation unit (33) calculates the resistance estimation value (Rs) using a current flowing into the motor (55) when the flag (Flg1) to perform the resistance estimation is received as input, and the resistance value setting unit (34) outputs the initial resistance value (R1Cs) to the sensorless control unit (30) when the flag (Flg1) to perform the resistance estimation is received as input, and wherein the resistance value setting unit (34) has: an initial resistance value calculation unit (341) for correcting the initial resistance value (R1Cs) based on the temperature information (Td); a first signal switch (342) which is to be switched depending on whether the flag (Flg1) is output to perform the resistance estimation or not; a second signal switch (343) which is to be switched depending on whether a device start flag (Flg2) is issued or not; and a previous value preservation unit (344) to maintain a resistance setpoint (R1C) which is an output value to be output by the second signal switch (343) to the sensorless control unit (30), wherein The first signal switch (342) receives the resistance estimate (Rs) and an output from the previous value maintenance unit (344) as inputs and, if the flag (Flg1) to perform the resistance estimate is not issued, outputs an output from the previous value maintenance unit (344) to the second signal switch (343), and if the flag (Flg1) to perform the resistance estimate is issued, outputs the resistance estimate (Rs) to the second signal switch (343), and The second signal switch (343) receives an output from the first signal switch (342) and the initial resistance value (R1Cs) corrected by the initial resistance value calculation unit (341) as inputs, and when the device start flag (Flg2) is issued, it outputs the initial resistance value (R1Cs) corrected by the initial resistance value calculation unit (341) as the resistance setpoint (R1C) to the sensorless control unit (30), and when the device start flag (Flg2) is not issued, it outputs an output from the first signal switch (342) as the resistance setpoint (R1C) to the sensorless control unit (30).

Description

Technical field

[0001] The present invention relates to a power conversion device for an electric vehicle that can start a rotating AC machine without the use of a speed sensor, and in particular to a power conversion device for an electric vehicle that estimates a resistance value of a rotating AC machine. background

[0002] The control system for starting a rotating AC machine without using a speed sensor is called "sensorless control." In recent years, sensorless control has become common for induction machines and position sensorless control for synchronous machines. With sensorless control, it is crucial to know the resistance value of an induction or synchronous machine. The resistance of a motor, such as a rotating AC machine for an electric vehicle, varies depending on the temperature. Therefore, if there is a discrepancy between the resistance value set by the control system and the actual resistance value in the motor, the desired output torque may not be achieved in some cases. Particularly with a large discrepancy, an electric vehicle may, in some instances, fail to start.

[0003] As a known technique for overcoming these problems, the patent literature cited below describes 1 a method for detecting a voltage applied to an induction machine for driving an electric vehicle and a current fed into the induction machine from the start of the electric vehicle until a point in time when the speed of the electric vehicle is in a low rotational speed range, and for subsequently estimating a primary and a secondary resistance of the induction machine. Furthermore, the patent literature cited below describes 2 a method for temporarily applying a DC voltage or a pulsating voltage to an induction machine for a specific period of time immediately after increasing an operating command from zero and subsequently estimating a primary resistance and a secondary resistance of the induction machine.

[0004] Both the methods described above in patent literature 1 and patent literature 2 relate to a method for measuring the resistance of a motor when the speed of an electric vehicle is in a low rotational speed range, where it is difficult to accurately estimate the primary and secondary resistances of a rotating motor. The reason for this difficulty is that as the motor rotates, mutual inductance, a primary leakage inductance, and a secondary leakage inductance are generated, so that the resulting value contains an impedance other than the primary and secondary resistances.

[0005] The patent literature 3 listed below describes a method carried out with a speed determination unit that determines that the speed of an AC lathe is zero, in which a primary resistance and a secondary resistance of the AC lathe are calculated based on an orthogonal axis current, a voltage command and a power run command, when the speed determination unit determines that the speed of the AC lathe is zero and an operating command is changed from a braking command to a power run command.

[0006] While the techniques described above in patent literature 1 and 2 have difficulties in obtaining accurate resistance values ​​due to an inductance component caused by the rotation of an AC lathe controlled in the speed sensorless control system, one of the operating modes described above in patent literature 3 can achieve more accurate resistance values ​​than the techniques described above in patent literature 1 and 2 because this operating mode estimates a primary resistance and a secondary resistance after inputting a power run command before the rotation of a rotating AC machine, i.e., when a voltage command of the d-axis and a current sensing value of the d-axis are obtained and an angular frequency is zero.

[0007] US 2011 / 0140646A1 relates to a method for controlling an induction machine with a rotor, wherein the method comprises the steps of obtaining a torque command, calculating an estimated squared value of a resistance of the rotor using the torque command, determining an offset for the resistance of the rotor, and generating an updated measure of the rotor resistance using the estimated squared value and the offset.

[0008] DE 10 2010 041 944 A1 concerns methods, systems and devices supplied for the sensorless control of a vector-controlled motor drive system which includes an electric motor used to drive an auxiliary or supplementary oil pump.

[0009] JP 2010 / 068 628 A concerns a motor control system with a resistance compensation function for a winding, whereby resistance fluctuations at low speeds are quickly detected in sensorless position or speed control to prevent performance degradation. For this purpose, a resistance index is determined from a current response under applied voltage and used to adapt the control system.

[0010] JP H09 - 233 900 A concerns a sensorless control method for a permanent magnet synchronous motor, in which the rotor position angle and speed are calculated from the phase current and voltage command vector in each control cycle. If the magnitude of the voltage command vector falls below a lower limit, a correction period is defined and a pulse voltage vector is added, the average value of which during the correction period is approximately 0. List of citations from patent literature Patent Literature 1: Japanese Patent Application Publication No. JP H04 - 8 192 A Patent Literature 2: Japanese Patent Application Publication No. JP H04 - 364 384 A Patent Literature 3: Japanese Patent No. JP 5 777 814 B2 Summary Technical Problem

[0011] All the aforementioned disclosures in patent literature 1 to 3 employ a method for starting a control system that estimates the resistance value of a motor. However, a condition must be met to start the control. If the condition is not met, it is common practice to use a default value as the resistance estimate. Since the resistance value of a motor is highly dependent on the ambient temperature or the temperature of the motor itself, there can be a large difference between the default value and the actual resistance value of the motor, thus significantly impairing the motor's control.

[0012] The present invention was made in view of the problems mentioned above, and one objective of the present invention is to provide a power conversion device for an electric vehicle which can improve the accuracy of estimating a resistance value of a motor even during a period in which a control system for estimating the resistance value of the motor cannot be started. Solution to the problem

[0013] To solve the aforementioned problems and achieve the objective, a power conversion device according to claim 1 is presented. Advantageous embodiments are described in the dependent claims. Advantageous effects of the invention

[0014] According to the present invention, this has the advantage that the accuracy of the estimation of a motor's resistance value can also be improved during a time when a control system for estimating the motor's resistance value cannot be started. Brief description of the drawings Fig. Figure 1 is a diagram illustrating an embodiment of a drive system for electric vehicles, which includes a power conversion device for an electric vehicle according to a first embodiment. Fig. Figure 2 is a block diagram that represents an example of a control system in the first embodiment. Fig. Figure 3 is a block diagram showing a detailed embodiment of a resistance value setting unit in the first embodiment. Fig. Figure 4 is a time diagram illustrating a situation of a change in a resistance setpoint specified by the resistance value setting unit of the first embodiment. Fig. Figure 5 is a flowchart illustrating the operating sequence of a resistance estimation unit and the resistance value setting unit in the first embodiment. Fig. Figure 6 is a block diagram that shows an example of a hardware configuration that implements the control in the first embodiment. Fig. Figure 7 is a block diagram that shows another example of the hardware configuration that implements the control in the first embodiment. Fig. Figure 8 is a diagram illustrating an embodiment of a vehicle drive system that includes a power conversion device according to a second embodiment. Fig. Figure 9 is a block diagram showing a detailed embodiment of a resistance value setting unit in the second embodiment. Fig. Figure 10 is a block diagram that represents an embodiment example of a control 3A in a third embodiment. Fig. Figure 11 is an explanatory diagram for an advantageous effect of a power conversion device according to the third embodiment. Description of the embodiments

[0015] A power conversion device for an electric vehicle according to the embodiments of the present invention (hereinafter simply referred to as "power conversion device") is described in detail below with reference to the drawings. The present invention is not necessarily limited by the following embodiments. First embodiment.

[0016] Fig. Figure 1 is a diagram illustrating an embodiment of a vehicle drive system that includes a power conversion device 1 according to a first embodiment. The power conversion device 1 according to the first embodiment includes an inverter 2, which converts direct current into alternating current and supplies the AC power obtained by the conversion to a motor 55 to drive the motor 55; a controller 3, which generates a voltage command V* to perform PWM control on the inverter 2 and outputs the generated command to the inverter 2; and current detectors 6a, 6b, and 6c, which are arranged on the AC side of the inverter 2 to detect phase currents flowing to the respective phases of the motor 55. An example of the motor 55 installed in an electric vehicle is an induction motor or a synchronous motor.A typical electric vehicle uses either an asynchronous motor or a synchronous motor.

[0017] One end on the DC side of inverter 2 is connected to an overhead line 51 via a pantograph 52, and another end on the DC side of inverter 2 is connected to a rail 54, which provides an electrical ground potential via a wheel 53. The DC power supplied from the overhead line 51 is fed to inverter 2 via the pantograph 52.

[0018] In the controller 3, an operating command PB is supplied from an external device 56, a temperature measurement value Td is supplied from a temperature sensor 5a, and the measured current values ​​iu, iv, and iw are supplied from the current detectors 6a, 6b, and 6c. In the example of Fig. In Figure 1, the temperature sensor 5a is mounted on a cooler 4. The cooler 4 is designed to cool switching elements (not shown) in the inverter 2. An example of the external device 56 is a driver's cab of an electric vehicle. In an electric vehicle with a general configuration, the cab is located in a control vehicle.

[0019] Although Fig. Figure 1 illustrates a case of using a current transformer (CT) for the current detectors 6a, 6b and 6c as an example; however, the current detectors 6a, 6b and 6c are not limited to current transformers and can be configured to detect phase currents using other publicly known techniques. Fig. Figure 1 illustrates an embodiment with three current detectors 6a, 6b and 6c as an example; however, the invention is not limited to such an embodiment. Each of the three current detectors 6a, 6b and 6c can be omitted if a relationship iu+iv+iw=0 is used, which is a three-phase equilibrium condition.

[0020] Fig. Figure 2 is a block diagram illustrating an embodiment of the control unit 3 according to the first embodiment. The control unit 3 comprises a sensorless control unit 30, a resistance estimation implementation and determination unit 31, a resistance estimation current control unit 32, a resistance estimation unit 33, a resistance value setting unit 34, and a signal switch 35, as shown in Figure 2. Fig. 2 shown.

[0021] An operating command PB from the external device 56, the current detection values ​​iu, iv, and iw detected by the current detectors 6a, 6b, and 6c, and a resistance value R1C set by the resistance value setting unit 34 are supplied to the sensorless control unit 30. A resistance value specified by the resistance value setting unit 34 is referred to as the "resistance setpoint." The sensorless control unit 30 generates a first voltage command V*1 using the operating command PB, the detected current values ​​iu, iv, and iw, and the resistance setpoint R1C. The first voltage command V*1 generated by the sensorless control unit 30 is supplied to the signal switch 35.

[0022] The design of the sensorless control unit 30 is publicly known, so a detailed description is omitted. The specific design is disclosed in Japanese patent no. 4459301, and reference can be made to the content of the patent publication.

[0023] The operating command PB is also fed to the resistance estimation implementation unit 31. At the time of input of the operating command PB, the resistance estimation implementation unit 31 generates a flag Flg1 to perform the resistance estimation. The flag Flg1 generated by the resistance estimation implementation unit 31 is fed to the resistance estimation current control unit 32, the resistance estimation unit 33, the resistance value setting unit 34, and the signal switch 35. The flag Flg1 is a timing signal for starting a control system to estimate a resistance value; that is, a trigger signal to start the control system to estimate a resistance value.

[0024] When the flag Flg1 is set to perform the resistance estimation, the resistance estimation current control unit 32 generates a second voltage command V*2, which is suitable for estimating a resistance value of the motor 55 using the detected current values ​​iu, iv, and iw. The second voltage command V*2 generated by the resistance estimation current control unit 32 is supplied to the signal switch 35.

[0025] When the resistance estimation flag Flg1 is applied, the resistance estimation unit 33 performs a calculation to estimate a resistance value Rs using the second voltage command V*2, generated by the resistance estimation current control unit 32, and the detected current values ​​iu, iv, and iw. The resistance value Rs estimated by the resistance estimation unit 33 is then sent to the resistance value setting unit 34.

[0026] When the flag Flg1 is entered for resistance estimation, the resistance value setting unit 34 outputs the resistance setpoint R1C held in the resistance value setting unit 34 to the sensorless control unit 30. The resistance value setting unit 34 is described in detail later.

[0027] The designs of the resistance estimation unit 31, the resistance estimation current control unit 32, and the resistance estimation unit 33 are publicly known, so their detailed description is omitted here. The specific designs of the units are disclosed in the patent literature 3 cited above (Japanese Patent No. 5777814), so reference can be made to the content of that patent publication. Furthermore, the design of the resistance estimation unit 33 is also disclosed in Japanese Patent No. 3771239 and Japanese Patent No. 4738549, which are referred to as prior art in patent literature 3, and the techniques disclosed in these prior art documents can also be used for the resistance estimation unit 33.

[0028] With reference to Fig. 2. Signal switch 35 selects either the first voltage command V*1, generated by the sensorless control unit 30, or the second voltage command V*2, generated by the resistance estimation current control unit 32 according to flag Flg1 for performing resistance estimation, and outputs the selected command outside the controller 3. More precisely, while flag Flg1 for performing resistance estimation is output, a switching contact of signal switch 35 is connected to side b, so that the second voltage command V*2 generated by the resistance estimation current control unit 32 is output outside the controller 3. Conversely, if flag Flg1 for performing resistance estimation is not output, the switching contact of signal switch 35 is connected to side a, so that the first voltage command V*1 generated by the sensorless control unit 30 is output outside the controller 3.The operation of control unit 3 is as described above.

[0029] Next, a detailed operation of the control unit 3 in the first embodiment will be described with reference to the Fig. 2 to 5 described. Fig. Figure 3 is a block diagram showing a detailed embodiment of the resistance value setting unit 34 in the first embodiment. Fig. Figure 4 is a time diagram illustrating a situation of a change in a resistance setpoint R1C set by the resistance value setting unit 34 of the first embodiment. Fig. Figure 5 is a flowchart illustrating the operating sequence of the resistance estimation unit 33 and the resistance value setting unit 34 in the first embodiment.

[0030] The resistance value setting unit 34 has an initial resistance value calculation unit 341, signal switches 342 and 343, and a previous value maintenance unit 344, as shown in Fig. Figure 3 illustrates this. A temperature sensing value Td is input into the initial resistance value calculation unit 341. Using the temperature sensing value Td, the initial resistance value calculation unit 341 generates an initial resistance value R1Cs. The initial resistance value R1Cs generated by the initial resistance value calculation unit 341 is input into the signal switch 343.

[0031] The function of the initial resistance value calculation unit 341 can be implemented by a table or by the following expression. R1Cs=R0{1+α(Td−T0)}

[0032] In the above expression (1) R1Cs is an initial resistance, R0 is a reference resistance, α is a temperature coefficient and T0 is a reference temperature.

[0033] Furthermore, in a case where the motor windings are made of copper, the following expression can be used to implement the function. R1Cs=R0{(234.5+Td) / (234.5+T0)}

[0034] The previous value maintenance unit 344 retains an output value of the signal switch 343, i.e., the resistance setpoint R1C, which is an output value of the resistance value setting unit 34. An output of the previous value maintenance unit 344 is fed to the signal switch 342.

[0035] Signal switch 342 selects either the resistance estimate Rs or the output of the previous value retention unit 344, depending on the resistance estimation method Flg1, and outputs the selected value to signal switch 343. More precisely, if the flag Flg1 for performing the resistance estimation is not output, a switching contact of signal switch 342 is connected to the b1 side, so that the output of the previous value retention unit 344 is selected and output to signal switch 343. When the flag Flg1 for performing the resistance estimation is output, the switching contact of signal switch 342 is connected to the a1 side, so that the resistance estimate Rs is selected and output to signal switch 343.

[0036] Furthermore, during the output of a device start flag Flg2, a switching contact of signal switch 343 is connected to the b2 side, so that the initial resistance value R1Cs generated by the initial resistance value calculation unit 341 is selected and output as the resistance setpoint R1C. Whereas, if the device start flag Flg2 is not output, the switching contact of signal switch 343 is connected to the a2 side, so that an output of signal switch 342 is selected and output as the resistance setpoint R1C.

[0037] Fig. Figure 4 illustrates a situation where the resistance setpoint R1C changes. When a device is started at time t1, the device start flag Flg2 is generated and an ON pulse is output until time t2, as shown in Figure 4. Fig. Figure 4 shows that when the device's start flag Flg2 falls at time t2, the switching contact of signal switch 343 is opened. Fig. 3 is connected to the a2 side. During this process, the signal switch 342, the signal switch 343, and the previous value maintenance unit 344 form a loop. Therefore, immediately before the contact of the signal switch 343 switches to the a2 side, the initial resistance value R1Cs generated by the initial resistance value calculation unit 341 is retained and locked by the previous value maintenance unit 344.

[0038] Furthermore, in Fig. 4. A waveform, marked with a thick dashed line, represents the initial resistance R1Cs generated by the initial resistance value calculation unit 341. The initial resistance value R1Cs at time t2, marked with a circle, is set as the resistance setpoint R1C and maintained until the resistance estimation.

[0039] When the flag Flg1 is output at time t3 to perform the resistance estimation, the switching contact of signal switch 342 is in Fig. 3 is connected to the a1 side, so that the resistance estimate Rs is used as the resistance setpoint R1C, and a value at time t4, when the flag Flg1 drops to perform the resistance estimate, is held and locked. If the resistance estimate is performed again at time t5, a value at time t6, when the flag Flg1 drops for the resistance estimate, is held and locked.

[0040] Fig. Figure 3 illustrates an embodiment in which the function of the resistance value setting unit 34 is implemented in hardware. If the function of the resistance value setting unit 34, including the resistance estimation unit 33, is implemented in software, this can be described in Fig. The 5 flowcharts shown can be used.

[0041] As in Fig. As shown in Figure 4, the device start flag Flg2 is output before the flag Flg1 for performing the resistance estimation is output. Therefore, a resistance value is initially set to a starting value, which is then corrected using a temperature sensing value, as described in step S101 of Figure 4. Fig. Figure 5 illustrates this. In step S102, it is determined whether a condition for performing the resistance estimation is met. If the condition for performing the resistance estimation is not met (NO in step S102), the resistance estimation is not performed, and the process from step S102 is repeated. On the other hand, if the condition for performing the resistance estimation is met (YES in step S102), the resistance estimation is performed in step S103, and the resistance value is set to an estimated resistance value in step S104.

[0042] As described above, the power conversion device according to the first embodiment corrects an initial resistance value using a detected temperature value and sets the resistance value of a motor to the corrected initial resistance value before the motor's resistance value is estimated. Therefore, it is possible to improve the accuracy of estimating a motor's resistance value even during a period when a control system for estimating the motor's resistance value cannot be started.

[0043] Furthermore, the power conversion device according to the first embodiment is configured such that a corrected initial resistance value is maintained in a resistance value setting unit, and the resistance value setting unit outputs the initial resistance value to a sensorless control unit until it receives a resistance estimate from a resistance estimation unit, and outputs the resistance estimate to the sensorless control unit after receiving the resistance estimate from the resistance estimation unit. Therefore, it is possible to smoothly perform control for estimating the resistance value of a motor both before and after the start of a control system for estimating the resistance value of the motor.

[0044] Although the temperature sensor 5a in Fig. Since the cooling element 1 is mounted in the cooler 4, it is possible that the temperature sensor 5a in the power conversion device 1 is mounted in a different area than the cooling element 4. Mounting the temperature sensor 5a in the power conversion device 1 has the advantage that a wiring line for transmitting the measured temperature value Td to the controller 3 can be run more easily than if the temperature sensor were mounted in the motor 55.

[0045] Furthermore, in a case where a train consisting of multiple electric vehicles has a train information management device, the power conversion device can be configured to receive temperature information managed by the train information management device without requiring the temperature sensor 5a. The train information management device manages information about the outside air temperature or temperature information from an air conditioning system and can improve the accuracy of estimating a resistance value of the motor 55 by receiving this temperature information and correcting the initial resistance value accordingly.

[0046] To conclude the description of the first embodiment, a hardware configuration that implements the function of the controller 3 in the first embodiment is described with reference to the Fig. 6 and Fig. 7 described. Fig. Figure 6 is a block diagram that shows an example of a hardware design that implements the control 3 in the first embodiment. Fig. Figure 7 is a block diagram that provides another example of the hardware design that implements the controller 3 according to the first embodiment.

[0047] To implement the function of the controller 3 described above, an embodiment can be used which includes a CPU (Central Processing Unit, main processor) 200, which performs the calculation, a memory 202, which stores a program to be read by the CPU 200, and an interface 204, which inputs and outputs signals, as shown in Fig. Figure 6 illustrates this. The CPU 200 can be a computing device such as a microprocessor, a microcomputer, a processor, a DSP (Digital Signal Processor), or the like. The memory 202 corresponds to a non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), Flash memory, EPROM (Erasable Programmable ROM), EEPROM (Electrically EPROM), or the like.

[0048] In particular, memory 202 stores a program for implementing the functions of the controller 3. The CPU 200 sends and receives the necessary information via interface 204 to perform various types of computational processing, which are explained in the first embodiment.

[0049] The CPU 200 and the one in Fig. The six depicted memory units 202 can be replaced by a processing circuit 203, as shown in Fig. Figure 7 shows the processing circuit 203. For example, it corresponds to a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or any combination thereof. Second embodiment.

[0050] Fig. Figure 8 is a diagram illustrating an embodiment of a vehicle drive system comprising a power conversion device 1A according to a second embodiment. The power conversion device 1A according to the second embodiment is configured by integrating a temperature sensor 5b, which is a second temperature sensor in addition to the temperature sensor 5a, into the power conversion device 1 according to the diagram in Figure 8. Fig. The first embodiment shown in Figure 1 is included. Other embodiments of the second embodiment are identical or equivalent to the embodiments of the first embodiment shown in Figure 1. Fig. 1 are shown, and thus similar or equivalent components are marked by similar reference symbols and redundant explanations of them are omitted.

[0051] Fig. Figure 9 is a block diagram showing a detailed embodiment of a resistance value setting unit 34A in the second embodiment. The resistance value setting unit 34A in the second embodiment corresponds to the resistance value setting unit 34 in the Fig. 3 first embodiment, wherein a minimum value calculation unit 345 is additionally provided on an input side of the initial resistance value calculation unit 341. Three detected temperature values ​​Td1, Td2 and Td3 are supplied to the minimum value calculation unit 345. The design of Fig. 9 is based on the assumption that the detected temperature value Td1 is temperature information from temperature sensor 5a, the detected temperature value Td2 is temperature information from temperature sensor 5b, and the detected temperature value Td3 is temperature information from a third temperature sensor located in Fig. 9 is not shown. Other configurations of the resistance value setting unit 34A are identical or equivalent to the one shown in Fig. 3 depicted design of the resistance value setting unit 34, so that similar or equivalent components are identified by similar reference symbols and redundant explanations are omitted.

[0052] Next, the operation of the resistance value setting unit 34A according to the second embodiment is described. As described above, the three detected temperature values ​​Td1, Td2, and Td3 are input into the minimum value calculation unit 345. The minimum value calculation unit 345 selects the smallest of the three detected temperature values ​​Td1, Td2, and Td3 and outputs the selected value to the initial resistance value calculation unit 341. The initial resistance value calculation unit 341 calculates the initial resistance value R1Cs using the expression (1) or (2) above, based on the temperature information transmitted by the minimum value calculation unit 345. The subsequent operations of the resistance value setting unit 34A are identical to those of the first embodiment.

[0053] Next, the significance of providing the minimum value calculation unit 345 is described. The second embodiment corrects information about an initial resistance value managed by the power conversion device 1A using information from a temperature sensor mounted in a section other than the motor 55, or from temperature information received from outside the power conversion device 1A. In such an embodiment, since the pattern of temperature increase of the motor 55 differs from the pattern of temperature increase of the power conversion device 1A or the ambient air, the use of unsuitable temperature information reduces the accuracy of the resistance value estimation of the motor 55.Furthermore, in a case where there is a variation in the estimated resistance value, it is possible to reduce the impact of a decrease in controllability more effectively when the estimated resistance value deviates to a smaller value than when it deviates to a larger value. Therefore, the second embodiment, which uses a plurality of detected temperature values, employs a configuration that selects the smaller of two or more temperature values.

[0054] In the design of Fig. 9. Temperature information from a train information management device can be added to the temperature information to be entered into the minimum value calculation unit 345. However, it is likely that the temperature information from the train information management device will differ significantly from the information from the other temperature sensors. In this case, it is conceivable that the differing temperature information is selected to estimate a resistance value of the motor 55. Therefore, in an embodiment that uses temperature information other than information from a temperature sensor, an average value can be calculated from the multitude of temperature information and an initial resistance value can be corrected using the average value.Furthermore, in a case where there is a variation in the estimated resistance value, it is possible to reduce the impact of a decrease in controllability more effectively when the estimated resistance value deviates to a smaller value than when it deviates to a larger value. Therefore, when using temperature information from the train information management device, a configuration can be employed in which, as in the example above, the minimum value is selected from the multitude of temperature information. Third embodiment.

[0055] Fig. Figure 10 is a block diagram illustrating an embodiment of a control unit 3A in a third embodiment. The control unit 3 in the first embodiment in Fig. The embodiment shown in Figure 2 is configured such that the resistance estimation unit 33 calculates the estimated resistance value Rs and the resistance value setting unit 34 outputs the setpoint resistance R1C remaining in the resistance value setting unit 34. In a case where the motor 55 is an induction machine, the estimated resistance value Rs is an estimated value of a primary resistance and the setpoint resistance R1C is a setpoint of the primary resistance, although descriptions of this are omitted in the first embodiment.Meanwhile, in the third embodiment, the control unit 3A is configured such that a resistance estimation unit 33a calculates the resistance estimate Rs, which is an estimate of a primary resistance, and a resistance estimate Rr, which is an estimate of a secondary resistance, and a resistance value setting unit 34a outputs the resistance setpoint R1C, which is a setpoint of the primary resistance, and a resistance setpoint R2C, which is a setpoint of the secondary resistance. In the third embodiment, Rs is referred to as the "primary resistance estimate," Rr as the "secondary resistance estimate," R1C as the "primary resistance setpoint," and R2C as the "secondary resistance setpoint." Other embodiments of the third embodiment are identical or equivalent to the embodiments of the first embodiment, which are described in [reference]. Fig. 2 are shown, and thus similar or equivalent components are marked by similar reference symbols and redundant explanations of them are omitted.

[0056] The resistance value setting unit 34a has a functional unit which, as in the design of the first embodiment, Fig. 3. An initial resistance value is calculated. The function for calculating the initial resistance can be implemented using a table or by using the following expressions. Rsc=Rs0{1+αs(Td−T0)} Rrc=Rr0{1+αr(Td−T0)}

[0057] In the above expressions (3) and (4), Rsc is an initial primary resistance value, Rs0 is a reference value for the primary resistance, αs is a temperature coefficient of a primary winding, Rrc is an initial secondary resistance value, Rr0 is a reference value for the secondary resistance, αr is a temperature coefficient of a secondary winding, and T0 is a reference temperature.

[0058] Furthermore, in a case where the motor windings are made of copper, the following expressions can be used to implement the function. Rsc=Rs0{(234.5+Td) / (234.5+T0)} Rrc=Rr0{(234.5+Td) / (234.5+T0)}

[0059] Next, advantageous effects achieved by estimating a secondary resistance of motor 55 will be discussed with reference to Fig. 11 described. Fig. Figure 11 is an explanatory diagram for an advantageous effect of a power conversion device according to the third embodiment.

[0060] In Fig. Figure 11 shows a waveform, indicated by a dashed line, representing the change in a torque command given by an upper control unit over time, and a waveform, indicated by a thick solid line, representing the change in an output torque over time. Assuming that Rr is a true value of a secondary resistance of an induction machine, the time required to follow the given torque command will be long if R2C > Rr for the secondary resistance setpoint R2C. Whereas if R2C <Rr für den sekundären Widerstandssollwert R2C erfüllt ist, ein Ausgangsdrehmoment erzeugt wird, das größer ist als der vorgegebene Drehmomentbefehl, und es benötigt viel Zeit, bis das Ausgangsdrehmoment auf den gegebenen Drehmomentbefehl zurückkehrt, und somit wird in diesem Fall auch die Zeit, die benötigt wird, um ihm zu folgen, lang.

[0061] Both the primary and secondary resistances of an induction machine vary with temperature. The primary resistance contributes to the stability of sensorless control, and the secondary resistance contributes to the transient response of torque control. As shown in the waveform in Fig. As shown in Figure 11, the accuracy of the estimation of a secondary resistance influences the transient behavior of the torque control.

[0062] In the power conversion device according to the third embodiment, a secondary resistance is set in addition to a primary resistance with a secondary resistance estimate value. This has the advantageous effect of improving the transient response performance of the torque control, in addition to ensuring good stability of the sensorless control.

[0063] The embodiments described above are only examples of the content of the present invention. These embodiments can be combined with other publicly known techniques and partially omitted and / or modified without deviating from the scope of the present invention. Reference character list

[0064] 1, 1A Power conversion device; 2 Inverter; 3, 3A Controller; 4 Cooler; 5a, 5b Temperature sensor; 6a, 6b, 6c Current detector; 30 Sensorless control unit; 31 Resistance estimation implementation determination unit; 32 Resistance estimation current control unit; 33, 33a Resistance estimation unit; 34, 34A, 34a Resistance value setting unit; 35, 342, 343 Signal switch; 51 Overhead line; 52 Pantograph; 53 Wheel; 54 Rail; 55 Motor; 56 External device; 200 CPU; 202 Memory; 203 Processing circuit; 204 Interface; 341 Initial resistance value calculation unit; 344 Previous value maintenance unit; 345 Minimum value calculation unit.

Claims

[1] Power conversion device (1) for an electric vehicle, comprising: an inverter (2) for driving a motor (55) installed in an electric vehicle; and a controller (3) for controlling the inverter (2) based on an operating command, where the control (3) a sensorless control unit (30) and corrects an initial resistance value set in the controller (3), based on temperature information from a temperature sensor (5a) provided in the power conversion device (1) or from temperature information transmitted from outside the power conversion device (1), sets a resistance value of the motor (55) to the corrected initial resistance value and causes the sensorless control unit (30) to operate based on the set resistance value of the motor (55), wherein the control (3) has: a resistance estimation unit (33) for calculating a resistance estimate value, which is an estimate of the resistance value of the motor (55), using a current flowing to the motor (55); a resistance value setting unit (34) to maintain the corrected initial resistance value, to output the initial resistance value to the sensorless control unit (30) until the resistance estimate is received from the resistance estimation unit (33), and to output the resistance estimate to the sensorless control unit (30) after the resistance estimate has been received from the resistance estimation unit (33); and a resistance estimation execution determination unit (31) to generate a flag (Flg1) to perform the resistance estimation when the operating command (PB) is received as input, and to supply the flag to the resistance estimation unit (33) and the resistance value setting unit (34), wherein the resistance estimation unit (33) calculates the resistance estimation value (Rs) using a current flowing into the motor (55) when the flag (Flg1) to perform the resistance estimation is received as input, and the resistance value setting unit (34) outputs the initial resistance value (R1Cs) to the sensorless control unit (30) when the flag (Flg1) to perform the resistance estimation is received as input, and wherein the resistance value setting unit (34) has: an initial resistance value calculation unit (341) for correcting the initial resistance value (R1Cs) based on the temperature information (Td); a first signal switch (342) which is to be switched depending on whether the flag (Flg1) is output to perform the resistance estimation or not; a second signal switch (343) which is to be switched depending on whether a device start flag (Flg2) is issued or not; and a previous value preservation unit (344) to maintain a resistance setpoint (R1C) which is an output value to be output by the second signal switch (343) to the sensorless control unit (30), wherein The first signal switch (342) receives the resistance estimate (Rs) and an output from the previous value maintenance unit (344) as inputs and, if the flag (Flg1) to perform the resistance estimate is not issued, outputs an output from the previous value maintenance unit (344) to the second signal switch (343), and if the flag (Flg1) to perform the resistance estimate is issued, outputs the resistance estimate (Rs) to the second signal switch (343), and The second signal switch (343) receives an output from the first signal switch (342) and the initial resistance value (R1Cs) corrected by the initial resistance value calculation unit (341) as inputs, and when the device start flag (Flg2) is issued, it outputs the initial resistance value (R1Cs) corrected by the initial resistance value calculation unit (341) as the resistance setpoint (R1C) to the sensorless control unit (30), and when the device start flag (Flg2) is not issued, it outputs an output from the first signal switch (342) as the resistance setpoint (R1C) to the sensorless control unit (30). [2] Power conversion device (1) for an electric vehicle according to claim 1, wherein the temperature sensor (5a) is arranged on a cooler (4) which cools a switching element included in the power conversion device (1). [3] Power conversion device (1) for an electric vehicle according to claim 1 or 2, wherein the temperature information transmitted from outside the power conversion device (1) is temperature information managed by a train information management device with which the electric vehicle is equipped. [4] Power conversion device (1) for an electric vehicle according to claim 1, wherein the temperature information is a plurality of information, and the resistance value setting unit (34A) selects a minimum value of parts of the temperature information and corrects the initial resistance value using the minimum value. [5] Power conversion device (1) for an electric vehicle according to claim 1, wherein the temperature information is a plurality of information, and the resistance value setting unit (34A) calculates an average value from parts of the temperature information and corrects the initial resistance value using the average value. [6] Power conversion device (1) for an electric vehicle according to one of claims 1, 4 and 5, wherein the motor (55) is an induction machine, the resistance estimation unit (33a) estimates a primary resistance and a secondary resistance of the induction machine, and the resistance value setting unit (34a) sets a primary resistance and a secondary resistance of the induction machine.

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