Drive control system and drive control method for power converter or railway vehicle

Abstract

In order to optimally drive and control a power converter in accordance with an actual operation condition within a range in which the temperature excess and damage of a semiconductor element constituting the power converter are not generated and to reduce the power consumption of a railway vehicle, this drive control system for the power converter for supplying power to a motor mounted on the railway vehicle is provided with an arithmetic device for outputting a command for driving and controlling the power converter constituted by a plurality of semiconductor elements. The arithmetic device calculates the current damage degree of the semiconductor element on the basis of the temperature history of the semiconductor element in the actual operation, calculates a future temperature history prediction value of the semiconductor element and a future damage degree prediction value of the semiconductor element on the basis of the operation history of the railway vehicle in the actual operation, selects a control parameter on the basis of the future temperature history prediction value of the semiconductor element, the current damage degree of the semiconductor element, and the future damage degree prediction value of the semiconductor element, and uses the control parameter to output the command.

Description

Drive control system and drive control method for power converter for railway vehicle

[0001] The present invention relates to a drive control system and a drive control method for a power converter that supplies power to a motor mounted on a railway vehicle.

[0002] Railway vehicles generally have a power conversion device installed under the floor that controls the power supplied to the traction motor. The power conversion device is equipped with a power converter consisting of semiconductor elements that perform DC / AC power conversion by switching current. The semiconductor elements generate heat when current is applied and when switching. If the semiconductor elements become too hot due to this heat, there is a concern that the conversion efficiency will decrease and the elements will deteriorate. Therefore, it is necessary to cool and control the semiconductor elements to maintain their temperature within a predetermined range.

[0003] On the other hand, to reduce the power consumption of railway vehicles, it is effective to increase the carrier frequency, which is one of the control parameters, to reduce harmonic losses in the traction motor. However, increasing the carrier frequency increases losses in the semiconductor elements that make up the power converter, which in turn increases the temperature of the semiconductor elements. Furthermore, the semiconductor elements are more susceptible to damage due to thermal stress caused by repeated temperature cycles.

[0004] Patent Documents 1 and 2 are cited as examples of power conversion devices mounted on railway vehicles. Patent Document 1 discloses a configuration including a power conversion unit that converts power from a power source and supplies the power to a load on an electric vehicle, a cooling unit that cools the power conversion unit, and a control unit that PWM controls the power conversion unit, and the control unit changes the carrier frequency of the PWM control, the number of carrier pulses, or the output power of the power conversion unit based on at least one or more parameters of the position of the electric vehicle, the temperature of the power conversion unit, the internal temperature of the electric vehicle control device, the outside air temperature, or the occupancy rate of the electric vehicle. This conventional technology is expected to provide an electric vehicle control device that has appropriate cooling performance and is small and low-cost.

[0005] Patent Document 2 discloses the configuration of an electric vehicle control device that includes a power conversion circuit provided for each motor of an electric vehicle, with an inverter that converts supplied power into AC power that controls the motor, and a control unit that starts or stops each inverter based on the input current value of the power conversion circuit or the current value of the motor when the electric vehicle is running in constant speed operation mode. This conventional technology is expected to have the effect of providing an electric vehicle control device that can more precisely control a highly efficient operating state while the electric vehicle is running.

[0006] JP 2016-140204 A JP 2015-6063 A

[0007] Generally, the control parameters of a power conversion device are set at the design stage so that the temperature of the semiconductor elements is below the allowable value and the life span is at least the planned operation period under the worst-case conditions on a representative line. However, in actual operation, the operating history of the railway vehicle, such as the motor current, ambient temperature, and occupancy rate, may not be under the worst-case conditions, and the temperature and damage level of the semiconductor elements may be within the allowable values.

[0008] Under these conditions, an effective way to reduce the power consumption of railway vehicles is to increase the carrier frequency, which is one of the control parameters, to reduce harmonic losses in the traction motor. However, since it is necessary to ensure that the temperature and damage level of semiconductor elements do not exceed their respective allowable values, it is necessary to predict the future temperature and damage level when the carrier frequency is changed.

[0009] Therefore, the present invention has been made in consideration of the above-mentioned problems, and aims to reduce the power consumption of railway vehicles in accordance with actual operating conditions, within a range that does not cause semiconductor elements to overheat or be damaged.

[0010] In order to solve the above problems, one representative drive control system of the present invention for a power converter that supplies power to a motor installed in a railway vehicle includes an arithmetic unit that outputs commands to drive and control a power converter composed of a plurality of semiconductor elements, and the arithmetic unit calculates the current degree of damage to the semiconductor elements based on the temperature history of the semiconductor elements during actual operation, calculates a predicted value of the future temperature history of the semiconductor elements and a predicted value of the future damage degree of the semiconductor elements based on the operating history of the railway vehicle during actual operation, and further selects control parameters based on the predicted value of the future temperature history of the semiconductor elements, the current degree of damage to the semiconductor elements, and the predicted value of the future damage degree of the semiconductor elements, and outputs commands using the control parameters.

[0011] According to the present invention, it is possible to optimally drive and control a power converter in accordance with actual operating conditions, without causing overheating or damage to semiconductor elements that constitute the power converter. Preferably, it is possible to reduce the power consumption of a railway vehicle in accordance with actual operating conditions. Problems, configurations, and effects other than those described above will become clear from the description of the following embodiments.

[0012] FIG. 1 is a diagram showing an overview of an example of the configuration of a railway vehicle power converter according to a first embodiment of the present invention. FIG. 2 is a diagram showing a block configuration and a processing flow of a drive control system for a railway vehicle power converter according to the first embodiment. FIG. 3 is a diagram showing a carrier pattern, which is one of the control parameters of the power converter, in the first to third embodiments. FIG. 4 is a diagram showing the relationship between the carrier frequency and each of the power consumption, the semiconductor element temperature, and the semiconductor element damage level in the first to third embodiments. FIG. 5 is a diagram showing the relationship between the carrier frequency and each of the power consumption, the semiconductor element temperature, and the semiconductor element damage level in the first to third embodiments. FIG. 6 is a diagram showing a block configuration and a processing flow of a drive control system for a railway vehicle power converter according to a second embodiment. FIG. 7 is a diagram showing a block configuration and a processing flow of a drive control system for a railway vehicle power converter according to a third embodiment.

[0013] Hereinafter, with reference to the drawings, a first to third embodiments of the present invention will be described as embodiments for carrying out the present invention. Note that the present invention is not limited to these embodiments. In addition, in the drawings, the same parts are denoted by the same reference numerals.

[0014] 1 is a diagram showing an outline of an example of the configuration of a drive control system for a railway vehicle power converter according to a first embodiment of the present invention. Note that components of the railway system that are not related to the present invention are omitted from FIG.

[0015] A power converter 2, a bogie 3, a motor 4, a transmission device 5, and a vehicle information device 6 are installed under the floor of the railway vehicle 1. In addition, a calculation device 11 is installed in a location separate from the railway vehicle 1 (for example, in a ground facility).

[0016] The power converter 2 supplies AC power 7 to a motor 4 installed on a carriage 3 to drive the motor 4. The power converter 2 also transmits a semiconductor element temperature history 8 (T1) during actual operation to a transmission device 5. Here, the power converter 2 is configured from a plurality of semiconductor elements, for example, in a bridge circuit. Since the plurality of semiconductor elements may be used as a semiconductor element module, the "semiconductor element" in the above-mentioned "semiconductor element temperature history" and the below-mentioned "semiconductor element damage level" and "semiconductor element power consumption" also includes semiconductor element modules.

[0017] The vehicle information device 6 transmits the driving history 9 during actual operation to the transmission device 5. The transmission device 5 transmits the semiconductor element temperature history 8 during actual operation and the driving history 9 during actual operation to the calculation device 11.

[0018] The arithmetic unit 11 transmits an optimum carrier pattern change command 10 to the transmission unit 5, and the transmission unit 5 transmits this optimum carrier pattern change command 10 to the power converter 2. The arithmetic unit 11 may also be configured to be installed under the floor of the railway vehicle 1, in which case it receives the semiconductor element temperature history 8 during actual operation and the operation history 9 during actual operation directly from the power converter 2 and the vehicle information unit 6, respectively, via wired communication, without going through the transmission unit 5.

[0019] Furthermore, the semiconductor element temperature history 8 during actual operation may be transmitted to the transmission device 5 via the vehicle information device 6, and the driving history 9 during actual operation may be transmitted to the transmission device 5 via the power converter 2, and the transmission route is not limited thereto. Furthermore, the power converter 2, the vehicle information device 6, and the transmission device 5 may be configured together as a single device.

[0020] 2 is a diagram showing a block configuration and a processing flow of the drive control system for a railway vehicle power converter according to Example 1. For the arithmetic unit 11 enclosed by a dashed line in the figure, an outline of the processing mode thereof is shown in the form of a flowchart of functional blocks.

[0021] The calculation device 11 receives the semiconductor element temperature history 8 (T1) during actual operation from the power converter 2 and the driving history 9 during actual operation from the vehicle information device 6 via the transmission device 5. The calculation device 11 then calculates the current semiconductor element damage level 12 (D1) based on the semiconductor element temperature history 8 (T1) during actual operation. Here, the semiconductor element damage level refers to the degree of deterioration of the element due to stress caused by heat (temperature rise).

[0022] Furthermore, the calculation device 11 calculates, based on the actual operation history 9, a semiconductor element temperature history 14 (T2), a semiconductor element damage degree 15 (D2), a semiconductor element power consumption 16 (Ps), and a motor power consumption 17 (Pm) as future predicted values, assuming that the operation history 9 will be repeated during the scheduled operation period of the railway vehicle 1. Hereinafter, the semiconductor element temperature history 14 (T2), the semiconductor element damage degree 15 (D2), the semiconductor element power consumption 16 (Ps), and the motor power consumption 17 (Pm), which are future predicted values, will be abbreviated as the future semiconductor element temperature history 14 (T2), the future semiconductor element damage degree 15 (D2), the future semiconductor element power consumption 16 (Ps), and the future motor power consumption 17 (Pm), respectively.

[0023] The processing execution cycle in the computing device 11 is assumed to be a processing cycle in which the processing is executed at a certain interval, such as once a month, once every three months, or once every six months.

[0024] From the results of these calculations, a carrier pattern determination 18 is performed. In this determination, thresholds are set for the temperature and damage level of the semiconductor element so as to prevent element destruction within the expected operation period. The carrier pattern determination 18 is performed based on the following conditions: for determining the temperature of the semiconductor element, a future semiconductor element temperature history 14 (T2) satisfies "T2≦temperature threshold"; for determining the damage level of the semiconductor element, the sum (D1+D2) of the current semiconductor element damage level 12 (D1) and the future semiconductor element damage level 15 (D2) satisfies "D1+D2≦damage level threshold"; and, for determining the damage level of the semiconductor element, the sum (Ps+Pm) of the future semiconductor element power consumption 16 (Ps) and the future motor power consumption 17 (Pm) is minimum ("Ps+Pm: minimum").

[0025] Here, to confirm that "Ps + Pm: minimum", the above determination is repeated using different control parameters. In this embodiment 1, it is assumed that the carrier pattern is changed as a control parameter, and future predicted values ​​are repeatedly calculated using the changed carrier pattern 13.

[0026] If the changed carrier pattern 13 satisfies the above three conditions (Yes), the calculation device 11 outputs an optimal carrier pattern change command 10 using it as the optimal control parameter and transmits it to the transmission device 5. If it does not satisfy the conditions (No), the carrier pattern is changed.

[0027] An optimum carrier pattern change command 10 is sent from the transmission device 5 to the power converter 2, and the power converter 2 outputs AC power 7 to the motor 4 using this optimum carrier pattern.

[0028] Here, the semiconductor element temperature history 8 (T1) during actual operation may use output values ​​from temperature sensors installed in the multiple semiconductor elements that make up the power converter 2, or may use values ​​obtained by performing a predetermined calculation on output values ​​from temperature sensors installed in other components such as a cooler (not shown) to which those semiconductor elements are attached.

[0029] Furthermore, the actual operation history 9 is a time history of the railway vehicle 1, including the vehicle's position, vehicle running speed, vehicle notch, outside air temperature of the vehicle, occupancy rate of the vehicle, current of the motor mounted on the vehicle, and carrier frequency of the power converter mounted on the vehicle. For example, the outside air temperature of the vehicle may be determined using a temperature detection means installed on the railway vehicle 1, or observation data from a meteorological station. The occupancy rate of the vehicle may be obtained from a separate management system. Furthermore, the frequency at which the optimal carrier pattern change command 10 is output is not limited.

[0030] 3 is a diagram showing a carrier pattern, which is one of the control parameters of the power converter 2 in the first to third embodiments. Compared to the current carrier pattern 19 (solid line), the modified carrier pattern 13 (dashed line) changes the carrier frequency in the asynchronous PWM region 20 and changes the modulation factor that changes the number of pulses in the synchronous PWM region 21. This changes the carrier pattern. However, the carrier pattern is changed within a range that does not cause induction interference or motor control failure.

[0031] 4 and 5 are diagrams showing the relationship between power consumption, semiconductor element temperature, and semiconductor element damage level, respectively, and carrier frequency in Examples 1 to 3. In Fig. 4 and Fig. 5, the upper graph shows the power consumption characteristics, the middle graph shows the semiconductor element temperature characteristics, and the lower graph shows the damage level characteristics.

[0032] Here, the power consumption is the sum (Ps+Pm) of the future semiconductor element power consumption 16 (Ps) and the future motor power consumption 17 (Pm) (hereinafter referred to as "future power consumption (Ps+Pm)"). As the carrier frequency increases, the number of switching operations of the semiconductor elements increases, and losses, i.e., future semiconductor element power consumption 16 (Ps), increase. On the other hand, as the carrier frequency increases, harmonic losses of the motor 4 decrease, and therefore future motor power consumption 17 (Pm) decreases. In other words, the sum of the two, the future power consumption (Ps+Pm), becomes a minimum value relative to the carrier frequency.

[0033] On the other hand, the maximum value (max) of the future semiconductor element temperature history 14 (T2) and the sum (D1+D2) of the current and future semiconductor element damage levels 12 and 15 increase as the carrier frequency increases, along with the increase in semiconductor element loss. As described above, thresholds (hereinafter referred to as the "temperature threshold" and "damage level threshold") are set for the temperature and damage level of the semiconductor element so as to prevent element breakdown within the planned operation period.

[0034] 4, carrier frequency A at which future power consumption (Ps+Pm) is minimized is a frequency lower than both the carrier frequency at which the maximum value (max) of future semiconductor element temperature history 14 (T2) coincides with the temperature threshold value and the carrier frequency at which the sum (D1+D2) of current and future semiconductor element damage levels 12 and 15 coincides with the damage level threshold value. In this case, carrier frequency A at which future power consumption (Ps+Pm) is minimized becomes the optimal value for reducing future power consumption (Ps+Pm), and is output as optimal carrier pattern change command 10.

[0035] On the other hand, in Figure 5, as shown in the lower graph, the trend of the semiconductor element damage level with respect to the carrier frequency is steep. In this case, the carrier frequency at which the future power consumption (Ps + Pm) is minimized is a frequency higher than carrier frequency B at which the sum (D1 + D2) of the current and future semiconductor element damage levels 12 and 15 coincides with the damage level threshold. Therefore, as shown in Figure 5, at the carrier frequency at which the future power consumption (Ps + Pm) is minimized, the future semiconductor element damage level will be greater than the damage level threshold. Therefore, carrier frequency B at which the sum (D1 + D2) of the current and future semiconductor element damage levels 12 and 15 coincides with the damage level threshold is the optimal value for reducing the future power consumption (Ps + Pm), and is output as optimal carrier pattern change command 10.

[0036] Finally, the effects of the first embodiment will be described. According to the first embodiment, the semiconductor element temperature, the semiconductor element damage level, and the power consumption can be calculated as future predicted values, and an optimal value for reducing the power consumption within a threshold value that will prevent element failure can be calculated. This makes it possible to reduce the power consumption of a railway vehicle according to the actual operating conditions, within a range that will prevent the semiconductor elements from overheating or being damaged. For example, even if the train runs under conditions that were not anticipated at the time of design, by optimizing the control parameters each time, the power consumption can be minimized within a range that will prevent failure during the operating period.

[0037] 6 is a diagram showing a block configuration and a processing flow of a drive control system for a railway vehicle power converter according to Example 2. In Example 2, when a future predicted value is calculated in the calculation device 11, a railway vehicle operating condition change scenario 22 is additionally input.

[0038] Here, the operation condition change scenario 22 may be, for example, at least one of the following for railway vehicles: change in operation time, fluctuation in occupancy rate, change in route, change in driver, presence or absence of automated driving, and weather change. These changes in operation conditions are also reflected in the calculation of future predicted values.

[0039] The method according to the second embodiment makes it possible to reduce the power consumption of railway vehicles in accordance with actual operating conditions, in response to anticipated future changes in operating conditions, to the extent that semiconductor elements do not overheat or become damaged.

[0040] 7 is a diagram showing a block configuration and a processing flow of a drive control system for a power converter for a railway vehicle according to Example 3. Example 3 also takes into consideration how to deal with the case where an appropriate solution is not obtained in carrier pattern determination 18.

[0041] For example, if the actual operating conditions are more severe than those assumed at the time of design, and no carrier pattern is found in which the sum of the current and future semiconductor element damage levels 12 and 15 (D1 + D2) is less than the damage level threshold, a semiconductor element replacement command 23 is output to the maintenance management system 24 to prompt replacement of the semiconductor element.

[0042] In the third embodiment, the number of times that the carrier pattern determination 18 is performed in one processing loop in the arithmetic unit 11 is limited to a predetermined number N, thereby performing the output determination 25 of the semiconductor element replacement command 23. However, the method of the output determination is not limited to this.

[0043] The method according to the third embodiment allows the semiconductor element to be replaced before it is damaged during operation, thereby making it possible to prevent unexpected failures.

[0044] Although the first to third embodiments have been described above as modes for carrying out the present invention, the present invention is not limited to the first to third embodiments described above, and various modifications are possible within the scope of the present invention.

[0045] 1: Railway vehicle, 2: Power converter, 3: Bogie, 4: Motor, 5: Transmission device, 6: Vehicle information device, 7: AC power, 8: Semiconductor element temperature history during actual operation (T1), 9: Operation history during actual operation, 10: Optimal carrier pattern change command, 11: Arithmetic unit, 12: Current semiconductor element damage level (D1), 13: Changed carrier pattern, 14: Future semiconductor element temperature history (T2), 15: Future semiconductor element damage level (D2), 16: Future semiconductor element power consumption (Ps), 17: Future motor power consumption (Pm), 18: Carrier pattern determination, 19: Current carrier pattern, 20: Asynchronous PWM region, 21: Synchronous PWM region, 22: Operation condition change scenario, 23: Semiconductor element replacement command, 24: Maintenance management system, 25: Output determination of semiconductor element replacement command

Claims

1. A drive control system for a power converter that supplies power to a motor mounted on a railway vehicle, comprising: a calculation device that outputs commands to drive and control the power converter, which is composed of a plurality of semiconductor elements; the calculation device calculates a current level of damage to the semiconductor elements based on the temperature history of the semiconductor elements during actual operation, calculates a predicted value of the future temperature history of the semiconductor elements and a predicted value of the future damage level of the semiconductor elements based on the operating history of the railway vehicle during actual operation, and further selects control parameters based on the predicted value of the future temperature history of the semiconductor elements, the current level of damage to the semiconductor elements, and the predicted value of the future damage level of the semiconductor elements, and outputs the commands using the control parameters.

2. A drive control system as described in claim 1, wherein the calculation device calculates a predicted future power consumption value of the semiconductor element and a predicted future power consumption value of the motor based on the operating history of the railway vehicle in actual operation, and selects the control parameters based on the predicted future power consumption value of the semiconductor element and the predicted future power consumption value of the motor under the condition that the predicted future temperature history value of the semiconductor element is below a predetermined temperature threshold and the damage level of the semiconductor element based on the current damage level of the semiconductor element and the predicted future damage level value of the semiconductor element is below a predetermined damage level threshold.

3. A drive control system as claimed in claim 1 or 2, characterized in that the arithmetic device is provided as a ground-side facility or on the vehicle body of the railway vehicle, and when the arithmetic device is provided as the ground-side facility, the drive control system further comprises a transmission device for sending and receiving data between the arithmetic device and the power converter.

4. A drive control system according to any one of claims 1 to 3, characterized in that the control parameter is a carrier pattern for driving the power converter.

5. A drive control system as claimed in any one of claims 1 to 4, characterized in that the operation history of the railway vehicle during actual operation is a time history of at least a predetermined number of the time histories of the position, running speed, notch, outside temperature, occupancy rate, motor current and carrier frequency of the power converter for the railway vehicle.

6. A drive control system as claimed in any one of claims 1 to 5, characterized in that the drive control system calculates future temperature history prediction values, damage prediction values ​​and power consumption prediction values ​​of the semiconductor elements, as well as future power consumption prediction values ​​of the motor, using an operating condition change scenario in which the operating conditions of the railway vehicle are changed based on the operating history of the railway vehicle in actual operation.

7. A drive control system as described in claim 6, characterized in that the operation condition change scenario is, with respect to the railway vehicle, at least one of the following: change in operation time, fluctuation in occupancy rate, change in route, change in driver, presence or absence of automated driving, and weather change.

8. A drive control system as claimed in any one of claims 1 to 7, characterized in that the arithmetic device generates a replacement command for the semiconductor element when the control parameter cannot be selected.

9. A method for controlling a power converter that supplies power to a motor mounted on a railway vehicle, comprising the steps of: acquiring a temperature history of the semiconductor elements during actual operation, and calculating a current level of damage to the semiconductor elements based on the temperature history; acquiring an operating history of the railway vehicle during actual operation, and calculating a predicted future temperature history value and a predicted future damage level value of the semiconductor elements based on the operating history; selecting control parameters based on the predicted future temperature history value of the semiconductor elements, the current level of damage to the semiconductor elements, and the predicted future damage level value of the semiconductor elements; and outputting a command to control the power converter using the control parameters.

10. A drive control method as described in claim 9, characterized in that it calculates a predicted future power consumption value of the semiconductor element and a predicted future power consumption value of the motor based on the operating history, and selects the control parameters based on the predicted future power consumption value of the semiconductor element and the predicted future power consumption value of the motor under the condition that the predicted future temperature history value of the semiconductor element is below a predetermined temperature threshold value and the damage level of the semiconductor element based on the current damage level of the semiconductor element and the predicted future damage level value of the semiconductor element is below a predetermined damage level threshold value.

11. A drive control method according to claim 9 or 10, characterized in that the control parameter is a carrier pattern for driving the power converter.

12. A drive control method as claimed in any one of claims 9 to 11, comprising the step of calculating future temperature history prediction values, damage prediction values ​​and power consumption prediction values ​​of the semiconductor elements, as well as future power consumption prediction values ​​of the motor, using an operating condition change scenario in which the operating conditions of the railway vehicle are changed based on the operating history of the railway vehicle in actual operation.

13. A drive control method according to any one of claims 9 to 12, characterized in that, when the control parameter cannot be selected, a command to replace the semiconductor element is generated.

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