JP2006238675A - Power conversion apparatus and method of setting overheat protection temperature therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power conversion apparatus, where the other power conversion part can normally perform an overheat protection operation, even if a part of power conversion parts performs overheat protection operation. <P>SOLUTION: The power conversion apparatus is provided with a plurality of power conversion parts, comprising at least first and second power conversion parts 11 and 12. An overheat protection setting value of the other power conversion part is changed, based on the presence or the absence of the overheat protection operation of one power conversion part. When one power conversion part performs a regular operation and when it performs the overheat protection operation, the other power conversion part can use the optimum overheat protection setting value. Thus, the overheat protection operation can be performed correctly at an assumed temperature, even if the heat that one power conversion part emits affects the temperature sensors 11b and 12b arranged in the other power conversion part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power conversion device, and particularly to a power conversion device including a plurality of power conversion units. The present invention also relates to an overheat protection temperature setting method for a power converter, and more particularly, to an overheat protection temperature setting method for a power converter including a plurality of power converters.

  In recent years, with the background of depletion of fossil fuels and the deterioration of the global environment, interest in automobiles that use electric energy, such as hybrid cars and fuel cell cars, has increased. In many cases, an automobile using electric energy is equipped with a motor for driving wheels, a high-voltage battery for supplying electric power to the motor, and a power conversion device for stepping down the voltage of the high-voltage battery. That is, while the voltage required by the motor for driving the wheels is relatively high at about 120 to 400 V, the voltage required by electric equipment such as an air conditioner and audio provided in the automobile is about 12 V. The voltage of the high-voltage battery is set to about 120 to 400 V, and the voltage is directly supplied to the motor for driving the wheel, and the voltage is stepped down by the power converter for the electric equipment such as the air conditioner and the audio. Is supplied.

Since this type of power conversion device has a switching circuit, a rectifier circuit, etc., a temperature sensor is provided for the purpose of preventing damage to the FET (field effect transistor) and diode contained therein. It is often done. When it is detected by such a temperature sensor that a predetermined overheat protection temperature has been reached, the control unit included in the power converter stops or limits the output, thereby causing damage to the FET or diode due to heat. (See Patent Document 1).
JP-A-9-37459 Japanese Patent Laid-Open No. 2001-289859

  However, the number of electrical devices mounted on automobiles is increasing year by year, and therefore, in recent years, power converters are required to have a larger output. In order to satisfy this, in addition to redesigning a higher power converter, a method of operating a low-power converter already designed in parallel can be considered. Development costs can be significantly reduced. An example of parallel operation is described in Patent Document 2, for example.

  However, when a plurality of power conversion units are operated in parallel, the heat generated by a certain power conversion unit is transferred to the other power conversion units, which causes a problem that the overheat protection operation by the temperature sensor becomes inaccurate. In other words, even if the output value of the temperature sensor is a certain value, the case where all of the power conversion units are operating in parallel and the case where only some of the power conversion units are operating The case where the actual temperature in a power converter part differs can be considered. This means that when only some of the power converters are operating, the output value of the temperature sensor is lower than the actual temperature compared to when all of the power converters are operating in parallel. Means. Therefore, if some power converters perform an overheat protection operation (output stop or output restriction), the remaining power converters will not easily enter the overheat protection operation, which may result in damage to the FET or diode. there were.

  Accordingly, an object of the present invention is a power conversion device including a plurality of power conversion units and an overheat protection temperature setting method for such a power conversion device, where some power conversion units perform an overheat protection operation. Even so, it is to provide a power conversion device and an overheat protection temperature setting method in which another power conversion unit can normally perform an overheat protection operation.

  A power conversion device according to the present invention is a power conversion device including a plurality of power conversion units including at least first and second power conversion units, based on the presence or absence of an overheat protection operation of the first power conversion unit. The overheat protection set value of the second power conversion unit is changed. According to the present invention, the second power conversion unit uses an optimum overheat protection setting value when the first power conversion unit performs normal operation and when the first power conversion unit performs overheat protection operation. It becomes possible. As a result, even if the heat generated by the first power conversion unit affects the temperature sensor provided in the second power conversion unit, it is possible to accurately perform the overheat protection operation at the assumed temperature. Become.

  In this case, it is preferable that the first and second power conversion units are arranged adjacent to each other. This is because in such a state, heat generated by one power conversion unit is easily transferred into the other power conversion unit.

  The power conversion device according to the present invention further includes a cooling mechanism provided in common to the plurality of power conversion units, and the overheat protection temperature is determined based on a temperature of a refrigerant used in the cooling mechanism. It is preferable. This makes it possible to perform the overheat protection operation more accurately at the assumed temperature.

  Moreover, it is preferable to reduce the overheat protection set value of the second power conversion unit in response to the first power conversion unit shifting from the normal operation to the overheat protection operation. According to this, even if the influence of heat from the first power conversion unit to the second power conversion unit is reduced due to the transition of the first power conversion unit from the normal operation to the overheat protection operation. The second power converter can detect abnormal overheating according to the actual temperature.

  In this case, it is preferable to lower the second overheat protection set value after a predetermined time has elapsed since the first power conversion unit shifted from the normal operation to the overheat protection operation. According to this, the problem that the second power conversion unit unnecessarily shifts to the overheat protection operation due to the influence of the residual heat is eliminated. In addition, it is particularly preferable that the overheat protection set value of the second power conversion unit is lowered stepwise or continuously in response to the first power conversion unit shifting from the normal operation to the overheat protection operation. According to this, it becomes possible to detect the appropriate abnormal overheating according to the change in the residual heat.

  In addition, when the heat generated by the second power conversion unit affects the temperature sensor provided in the first power conversion unit, based on the presence or absence of the overheat protection operation of the second power conversion unit, It is preferable to change the overheat protection set value of the first power converter. On the other hand, if the heat generated by the second power converter does not substantially affect the temperature sensor provided in the first power converter, the presence or absence of the overheat protection operation of the second power converter Regardless, it is preferable to keep the overheat protection set value of the first power conversion unit constant.

  In the present invention, it is preferable that at least some of the plurality of power conversion units are connected so as to be capable of parallel operation, and it is preferable that all of the plurality of power conversion units are DC / DC converters. According to this, it becomes possible to utilize suitably as a power converter device provided between the high voltage battery and low voltage battery of a car.

  An overheat protection temperature setting method for a power conversion device according to the present invention is an overheat protection temperature setting method for a power conversion device including a plurality of power conversion units including at least first and second power conversion units, In a state in which the first and second power conversion units are normally operated, the first temperature when the temperature of the refrigerant used in the cooling mechanism provided in common for the plurality of power conversion units reaches a set temperature. An output value of a temperature sensor provided in one power conversion unit is set as a first overheat protection set value of the first power conversion unit, at least the first power conversion unit is normally operated, and the second The output value of the temperature sensor provided in the first power conversion unit when the temperature of the refrigerant reaches the set temperature in a state where the power conversion unit of the first power conversion unit is in the overheat protection operation is used as the first power conversion. Set as the second overheat protection setpoint Characterized in that it.

  According to such a method, the temperature sensor in which the second power conversion unit first shifts to the overheat protection operation during actual use, whereby the second power conversion unit is provided in the first power conversion unit. Even if the effect on the temperature is reduced, accurate temperature monitoring can be performed in consideration of this.

  In this case, the output of the temperature sensor provided in the second power conversion unit when the temperature of the refrigerant reaches the set temperature with at least the first and second power conversion units operating normally. The value is set as the first overheat protection setting value of the second power conversion unit, at least the second power conversion unit is normally operated, and the first power conversion unit is in the overheat protection operation. The output value of the temperature sensor provided in the second power conversion unit when the temperature of the refrigerant reaches the set temperature is set as the second overheat protection set value of the second power conversion unit. It is preferable. According to this, at the time of actual use, the first power conversion unit first shifts to the overheat protection operation, and thereby the first power conversion unit affects the temperature sensor provided in the second power conversion unit. Even if it is reduced, accurate temperature monitoring can be performed in consideration of this.

  Thus, according to the present invention, even when heat generated by a certain power conversion unit affects a temperature sensor provided in another power conversion unit, it is possible to detect abnormal overheating in consideration of this. Therefore, it is possible to accurately perform the overheat protection operation at the assumed temperature regardless of the operation state of other power conversion units.

  Therefore, it is possible to effectively prevent damage to FETs and diodes due to heat even when a low-power power conversion unit that has already been designed is operated in parallel, rather than redesigning a high-power power conversion device. It becomes possible.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing a configuration of a power conversion device 10 according to a preferred first embodiment of the present invention.

  As shown in FIG. 1, the power conversion device 10 according to the present embodiment includes two power conversion units 11 and 12 and a cooling mechanism 19 provided in common to the two power conversion units 11 and 12. Configured. The power conversion units 11 and 12 have main circuit units 11a and 12a and temperature sensors 11b and 12b, respectively, and are accompanied by operations of the main circuit units 11a and 12a including a switching circuit and a rectifier circuit (not shown). The generated heat is monitored by the corresponding temperature sensors 11b and 12b. For example, a thermistor can be used as the temperature sensors 11b and 12b.

  In addition to the switching circuit and the rectifier circuit, the main circuit units 11a and 12a include overheat detection units 11c and 12c, and two setting units 11d and 11e and setting units 12d and 12e, respectively. The setting units 11d and 11e store first and second overheat protection setting values for the power conversion unit 11, respectively. The setting units 12d and 12e store first and second settings for the power conversion unit 12, respectively. The overheat protection set value is stored.

  The overheat detection unit 11c compares the output value of the temperature sensor 11b with the first overheat protection set value stored in the setting unit 11d or the second overheat protection set value stored in the setting unit 11e, and the temperature sensor When the output value of 11b exceeds the first or second overheat protection set value, it is determined that the overheat is abnormal, and the power conversion unit 11a is shifted from the normal operation to the overheat protection operation. Whether the output value of the temperature sensor 11 b is compared with the first or second overheat protection set value is controlled by the overheat detection unit 12 c included in the power conversion unit 12. Similarly, the overheat detection unit 12c compares the output value of the temperature sensor 12b with the first overheat protection set value stored in the setting unit 12d or the second overheat protection set value stored in the setting unit 12e. When the output value of the temperature sensor 12b exceeds the first or second overheat protection set value, it is determined that the overheat is abnormal, and the power conversion unit 12 is shifted from the normal operation to the overheat protection operation. Whether the output value of the temperature sensor 12 b is compared with the first or second overheat protection set value is controlled by the overheat detection unit 11 c included in the power conversion unit 11. Here, the “overheat protection operation” is an operation to stop or limit the output. When the overheat protection operation is performed, the heat generation of the FETs and diodes included in the main circuit portions 11a and 12a is reduced. Damage due to is prevented in advance.

  The cooling mechanism 19 is configured by a pipe through which a refrigerant 19a such as cooling water or air flows, and the power conversion units 11 and 12 are cooled by the refrigerant 19a flowing through the pipe. In normal operation, the power conversion units 11 and 12 are sufficiently cooled by the cooling mechanism 19. However, when the overload state continues for a long time or when the cooling mechanism 19 has a problem. The power converters 11 and 12 may be abnormally overheated. As described above, such abnormal overheating is monitored by the temperature sensors 11b and 12b and detected by the overheat detection units 11c and 12c.

  In the present embodiment, when both of the power conversion units 11 and 12 are performing normal operation, the overheat detection units 11c and 12c are the first values stored in the output values of the temperature sensors 11b and 12b and the setting units 11d and 12d. The overheat protection set value is compared with each other to detect abnormal overheat. Then, when one of the overheat detection units 11c and 12c detects abnormal overheating and the corresponding power conversion unit shifts from the normal operation to the overheat protection operation based on this, the overheat detection unit included in the power conversion unit is the other A switching signal S is sent to the overheat detection unit included in the power conversion unit. That is, when the power conversion unit 11 shifts to the overheat protection operation, the switching signal S is sent from the overheat detection unit 11c to the overheat detection unit 12c, and when the power conversion unit 12 shifts to the overheat protection operation, from the overheat detection unit 12c. A switching signal S is sent to the overheat detection unit 11c.

  In response to this, the other overheat detecting unit compares the output value of the temperature sensor with the second overheat protection set value stored in the setting unit 11e or the setting unit 12e, thereby detecting abnormal overheating. Switch to the mode you want. For example, when the power conversion unit 11 shifts to the overheat protection operation, the overheat detection unit 12c included in the power conversion unit 12 sets the output value of the temperature sensor 12b and the second overheat protection setting stored in the setting unit 12e. The mode is switched to a mode for detecting abnormal overheating by comparing the value. As described above, in the present embodiment, the overheat protection set value of the other power converters 11 and 12 is changed in response to the transition of the one power converters 11 and 12 to the overheat protection operation.

  Here, the second overheat protection set value in each of the power converters 11 and 12 is set to a lower level (corresponding to a low temperature) than the corresponding first overheat protection set value. This considers the influence which the heat | fever which one of the power conversion parts 11 and 12 emits has on the temperature sensor with which the other was equipped. That is, when the power conversion units 11 and 12 are operating in parallel in normal operation, the temperature sensor 11b is not only the main circuit unit 11a of the power conversion unit 11 but also the heat generated by the main circuit unit 12a of the power conversion unit 12. Similarly, the temperature sensor 12b is affected not only by the main circuit unit 12a of the power conversion unit 12 but also by heat generated by the main circuit unit 11a of the power conversion unit 11. However, for example, when only the power conversion unit 11 is operating alone, the temperature sensor 11b is not affected by the heat generated by the main circuit unit 12a of the power conversion unit 12, so that the inside of the main circuit unit 11a. Even if the actual temperature is the same, a phenomenon occurs in which the output value of the temperature sensor 11b is lower than that in the case of parallel operation.

  This means that even when the output value of the temperature sensor 11b is the same, the power conversion units 11 and 12 are operating in parallel operation in normal operation and the case where only the power conversion unit 11 is operating independently. This means that the actual temperature of the main circuit unit 11a of the power conversion unit 11 is different. In consideration of this point, in the present embodiment, in response to the transition of one of the power conversion units 11 and 12 from the normal operation to the overheat protection operation, the other overheat protection set value of the power conversion units 11 and 12 is set. It is decreasing. Thereby, even when one power conversion unit is performing the overheat protection operation, the other power conversion unit can detect abnormal overheating according to the actual temperature.

  However, even if one of the power conversion units 11 and 12 shifts from the normal operation to the overheat protection operation, it is affected by the residual heat for a while, so that one of the power conversion units 11 and 12 operates from the normal operation to the overheat protection operation. If the overheat protection setting value of the other power converter is reduced immediately in response to the transition to, the other power converter unnecessarily transitions to the overheat protection operation in cases where the effect of residual heat is large. It can be considered. If this point is considered, after one of the power conversion units 11 and 12 shifts from the normal operation to the overheat protection operation, a predetermined time elapses, and then the overheat protection set value of the other power conversion unit is decreased. Is preferred.

  In addition, since the remaining heat gradually decreases, in consideration of this point, in response to the transition of one of the power conversion units 11 and 12 from the normal operation to the overheat protection operation, the overheat protection of the other power conversion unit is performed. More preferably, the set value is lowered stepwise or continuously. According to this, it becomes possible to detect the appropriate abnormal overheating according to the change in the residual heat.

  Next, an overheat protection temperature setting method for the power converter 10 will be described.

  FIG. 2 is a flowchart for explaining a method for setting the overheat protection temperature for the power converter 10.

  As shown in FIG. 2, first, the power conversion units 11 and 12 are normally operated in a state where the refrigerant 19a is passed through the cooling mechanism 19 (step S1). As a result, the temperature of the refrigerant 19a gradually increases. The temperature of the refrigerant 19a is accurately measured by a thermometer (not shown), and it is determined whether or not the refrigerant 19a has reached a preset temperature (for example, 70.0 ° C.) (step S2). When it is detected that the set temperature has been reached (step S2: YES), the output value of the temperature sensor 11b at that time is set as the first overheat protection set value of the power conversion unit 11 in the setting unit 11d. Then, the output value of the temperature sensor 12b is set in the setting unit 12d as the first overheat protection set value of the power conversion unit 12 (step S3). Note that the first overheat protection set value set in the power conversion unit 11 and the first overheat protection set value set in the power conversion unit 12 do not necessarily match. This is because the characteristics of the temperature sensor 11b and the temperature sensor 12b do not necessarily match, and the heat that the temperature sensor 11b feels when the refrigerant 19a reaches the set temperature does not necessarily match the heat that the temperature sensor 12b feels. It is. Moreover, the influence of the heat which one of the power conversion parts 11 and 12 has on the temperature sensor provided in the other power conversion part, and the temperature sensor in which the other of the power conversion parts 11 and 12 is provided in the one power conversion part Another reason is that the effect of heat does not always match.

  Next, the power conversion unit 12 is shifted to the overheat protection operation in a state where the power conversion unit 11 is normally operated (step S4). And the temperature of the refrigerant | coolant 19a is measured again, and it is judged whether this reached said set temperature (step S5). When it is detected that the set temperature has been reached (step S5: YES), the output value of the temperature sensor 11b at that time is set in the setting unit 11e as the second overheat protection set value of the power conversion unit 11. (Step S6). Here, since the power conversion unit 12 performs the overheat protection operation, the temperature sensor 11b is not affected by the heat from the main circuit unit 12a of the power conversion unit 12 (or is less affected). The second overheat protection set value is lower than the overheat protection set value.

  Next, the power conversion unit 11 is shifted to the overheat protection operation, and the power conversion unit 11 is shifted to the normal protection operation (step S7). And the temperature of the refrigerant | coolant 19a is measured again, and it is judged whether this reached said set temperature (step S8). When it is detected that the set temperature has been reached (step S8: YES), the output value of the temperature sensor 12b at that time is set in the setting unit 12e as the second overheat protection set value of the power conversion unit 12. (Step S9). Here, since the power conversion unit 11 performs the overheat protection operation, the temperature sensor 12b is not affected by the heat from the main circuit unit 11a of the power conversion unit 11 (or is less affected). The second overheat protection set value is lower than the overheat protection set value.

  Also in this case, the second overheat protection set value set in the power conversion unit 11 and the second overheat protection set value set in the power conversion unit 12 do not necessarily match. The reason is as described above.

  Thus, the overheat protection temperature setting for the power converter 10 is completed. If the overheat protection setting is performed by such a method, it cannot be determined which of the power converters 11 and 12 first shifts to the overheat protection operation during actual use. However, one of the power conversion units 11 and 12 shifts from the normal operation to the overheat protection operation, thereby reducing the influence of one of the power conversion units 11 and 12 on the temperature sensor provided in the other power conversion unit. However, since accurate temperature monitoring in consideration of this can be performed, it becomes possible to effectively prevent the FETs and diodes included in the main circuit portions 11a and 12a from being damaged.

  In the overheat protection temperature setting method shown in FIG. 2, the first overheat protection set value for the power conversion units 11 and 12 is set in steps S1 to S3, and then the power conversion unit in steps S4 to S6. 11 is set, and finally, the second overheat protection setting value for the power converter 12 is set in steps S7 to S9. However, this order is not particularly limited. Absent.

  Next, a second preferred embodiment of the present invention will be described.

  FIG. 3 is a schematic diagram showing the configuration of the power conversion device 20 according to the preferred second embodiment of the present invention.

  As shown in FIG. 3, the power conversion apparatus 20 according to the present embodiment has the positions of the temperature sensors 11 b and 12 b unevenly distributed in the arrangement direction of the power conversion units 11 and 12 and is included in the power conversion unit 11. The setting unit 11e is omitted from the power converter 10 described above. Since it is the same as that of the power converter device 10 mentioned above about the other points, the same code | symbol is attached | subjected to the same component and the overlapping description is abbreviate | omitted. In the present embodiment, since the positions of the temperature sensors 11b and 12b are unevenly distributed, the influence of the heat that the power conversion unit 11 gives to the temperature sensor 12b of the power conversion unit 12 is more affected by the power conversion unit 12 than the power conversion unit 11. The influence of heat on the temperature sensor 11b is sufficiently larger than the influence of heat on the temperature sensor 11b, and the influence of heat on the temperature sensor 11b of the power converter 11 can be almost ignored.

  In such a case, when the power conversion unit 11 shifts from the normal operation to the overheat protection operation, the overheat protection set value of the power conversion unit 12 is changed from the first overheat protection set value to the second overheat protection set value. On the other hand, even if the power conversion unit 12 shifts from the normal operation to the overheat protection operation, it is not necessary to change the overheat protection set value of the power conversion unit 11. That is, it is only necessary to keep the overheat protection set value of the power converter 11 constant regardless of the presence or absence of the overheat protection operation of the power converter 12. For this reason, it is not necessary to provide a setting unit for storing the second overheat protection set value in the power conversion unit 11, and the overall circuit scale can be reduced.

  The overheat protection temperature setting for the power converter 20 can be performed by omitting Steps S4 to S6 in the flowchart shown in FIG. Therefore, in the present embodiment, it is possible to complete the overheat protection temperature setting with fewer procedures.

  Next, a preferred third embodiment of the present invention will be described.

  FIG. 4 is a schematic diagram showing a configuration of a power conversion device 30 according to a preferred third embodiment of the present invention.

  As shown in FIG. 4, the power conversion device 30 according to the present embodiment includes three power conversion units 31 to 33 and a cooling mechanism 19 provided in common to the three power conversion units 31 to 33. Configured. As in the above embodiments, the power conversion units 31 to 33 have main circuit units 31a to 33a and temperature sensors 31b to 33b, respectively.

  These three power conversion units 31 to 33 are arranged in a line in this order as shown in FIG. 4. Among these, the power conversion units 31 and 33 arranged at the end include two setting units 31 d and 31 e and Although the setting units 33d and 33e are provided, the power conversion unit 32 disposed in the center is provided with three setting units 32d, 32e, and 32f. The setting units 31d, 32d, and 33d each store a first overheat protection set value, and the setting units 31e, 32e, and 33e each store a second overheat protection set value. The setting unit 32f stores a third overheat protection set value.

  The power conversion units 31 and 33 arranged at the end refer to the first overheat protection setting value stored in the setting units 31d and 33d when the adjacent power conversion unit 32 is operating normally. When abnormal overheating is detected and the power conversion unit 32 is performing an overheat protection operation, the abnormal overheat is detected with reference to the second overheat protection setting values stored in the setting units 31e and 33e. . As already described, the second overheat protection set value is set to a lower level (corresponding to a low temperature) than the first overheat protection set value, and thereby the adjacent power converter 32 performs normal operation. It is possible to detect abnormal overheating in accordance with the actual temperature in both cases where the operation is performed and the overheat protection operation is performed.

  On the other hand, the power conversion unit 32 located in the center refers to the first overheat protection setting value stored in the setting unit 32d when both of the power conversion units 31 and 33 are operating normally. When the abnormal overheat is detected and one of the power converters 31 and 33 performs a normal operation and the other performs an overheat protection operation, the second overheat protection set value stored in the setting unit 32e is set. Referring to the detection of abnormal overheat, when both power converters 31 and 33 are performing the overheat protection operation, the abnormal overheat is referred to by referring to the third overheat protection set value stored in the setting unit 32f. Detection is performed. The third overheat protection set value is set at a lower level (corresponding to a low temperature) than the second overheat protection set value. Thereby, when both of the adjacent power conversion units 31 and 33 are performing normal operation, when both are performing overheat protection operation, and when both are performing overheat protection operation, However, it is possible to detect abnormal overheating according to the actual temperature.

  As described above, the present embodiment includes the three power conversion units 31 to 33, and changes the overheat protection set value depending on whether the adjacent power conversion unit performs the normal operation or the overheat protection operation. As a result, it is possible to accurately detect abnormal overheating according to the actual temperature even for the power converter 32 that is most susceptible to the influence of heat from the other because it is located in the center. Such an overheat protection temperature setting method for the power conversion device 30 is the same as the method described with reference to FIG.

  In the present embodiment, the overheat protection set value of the power conversion unit 33 is not changed depending on whether the power conversion unit 31 performs a normal operation or an overheat protection operation. Similarly, the power conversion unit 33 The overheat protection set value of the power converter 31 is not changed depending on whether the normal operation or the overheat protection operation is performed. This is because it is considered that there is almost no influence of heat between the power conversion units 31 and 33 arranged at the end. If there is a substantial heat effect between the power conversion units 31 and 33, the overheat protection set value may be changed in consideration of this. In this case, the power converters 31 and 33 also require three setting units.

  In the present embodiment, when one of the power conversion units 31 and 33 performs a normal operation and the other performs an overheat protection operation, the first conversion is performed regardless of which power conversion unit is operating normally. 2 is used to detect abnormal overheating. This is because the position of the temperature sensor is not unevenly distributed in the arrangement direction of the power conversion units 31 to 33, and therefore, the temperature sensor 32b included in the power conversion unit 32 is influenced by the heat received from the power conversion unit 31 and the power This is because the effects of heat received from the conversion unit 31 are substantially equal. If these influences are substantially different, the overheat protection set value may be changed in consideration of this. In this case, the power conversion unit 32 needs four setting units.

  Next, a preferred fourth embodiment of the present invention will be described.

  FIG. 5 is a schematic diagram showing a configuration of a power conversion device 40 according to a preferred fourth embodiment of the present invention.

  As shown in FIG. 5, the power conversion device 40 according to the present embodiment includes the points where the positions of the temperature sensors 31 b, 32 b, and 33 b are unevenly distributed in the arrangement direction of the power conversion units 31 to 33, and the power conversion unit 31, 32 is different from the above-described power converter 30 in that the setting units 31e and 32f included in 32 are omitted. Since it is the same as that of the power converter device 30 mentioned above about the other point, the same code | symbol is attached | subjected to the same component and the overlapping description is abbreviate | omitted.

  In the present embodiment, since the positions of the temperature sensors 31b, 32b, and 33b are unevenly distributed, the influence of the heat that the power conversion unit 31 has on the temperature sensor 32b of the power conversion unit 32 is converted by the power conversion unit 32 into power conversion. The influence of heat on the temperature sensor 31b of the power converter 31 is sufficiently larger than the influence of heat on the temperature sensor 31b of the section 31, and the influence of heat on the temperature sensor 31b of the power converter 31 can be almost ignored. Similarly, the influence of the heat that the power converter 32 gives to the temperature sensor 33b of the power converter 33 is sufficiently larger than the influence of the heat that the power converter 33 gives to the temperature sensor 32b of the power converter 32. The influence of heat that the conversion unit 33 gives to the temperature sensor 32b of the power conversion unit 32 can be almost ignored.

  In such a case, the overheat protection setting value of the power conversion unit 32 may be determined depending on whether the power conversion unit 31 is performing normal operation or overheat protection operation, and the overheat protection setting of the power conversion unit 33 is determined. The value may be determined depending on whether the power conversion unit 32 is performing a normal operation or an overheat protection operation. On the other hand, the overheat protection set value of the power conversion unit 31 may be constant regardless of the presence or absence of the overheat protection operation of the power conversion units 32 and 33. According to this, since the number of setting units can be reduced compared to the power conversion device 30 according to the third embodiment, the overall circuit scale can be reduced. In this connection, it is also possible to complete the overheat protection temperature setting with fewer procedures.

  As mentioned above, although several power converter devices by preferable embodiment were demonstrated, these are especially suitable as a power converter device for motor vehicles.

  FIG. 6 is a block diagram schematically showing main parts of an automobile equipped with the power conversion device according to the present invention.

  As shown in FIG. 6, when the power conversion device according to the present invention is used for an automobile, the power conversion device 10 (20, 30, 40) is provided between a high voltage battery 41, an electric device 42, and a low voltage battery 46. The high voltage of about 120 to 400 V supplied from the high voltage battery 41 is stepped down to about 12 V and supplied to the electric device 42, and the low voltage battery 46 is charged. That is, in this case, the power converter 10 (20, 30, 40) is a DC / DC converter. Examples of the electric device 42 include an air conditioner and an audio device provided in an automobile. Charging the high voltage battery 41 is performed by electric power supplied from the power generation device 43. The output of the high voltage battery 41 is also supplied to the motor 44, and the motor 44 drives the drive system 45 based on the high voltage (about 120 to 400V) supplied from the high voltage battery 41. In the fuel cell vehicle, the fuel cell main body serves as the power generation device 43, and in the hybrid vehicle, the motor 44 also serves as the power generation device 43.

  In this case, if the electrical equipment 42 and the low-voltage battery 46 are one system, as shown in FIGS. 7 and 8, all the power converters included in the power converter 10 (20, 30, 40) should be connected in parallel. That's fine. 7 shows a state in which the power converters 11 and 12 constituting the power converter 10 (see FIG. 1) or the power converter 20 (see FIG. 3) are connected in parallel, and FIG. 8 shows the power converter 30. (Refer FIG. 4) or the power converters 31-33 which comprise the power converter device 40 (refer FIG. 5) are shown in the state connected in parallel.

  On the other hand, if there are a plurality of systems of electrical equipment 42 and low-voltage batteries 46, as shown in FIGS. 9 to 11, a part or all of the power converters included in the power converter 10 (20, 30, 40) are individually provided. Just connect. 9 shows a state in which the power conversion units 11 and 12 constituting the power conversion device 10 (see FIG. 1) or the power conversion device 20 (see FIG. 3) are connected to the electric system 42 and the low-voltage battery 46 in different systems, respectively. FIG. 10 shows the power converters 31 and 32 and the power converter 33 constituting the power converter 30 (see FIG. 4) or the power converter 40 (see FIG. 5) as separate electric devices 42 and FIG. 11 shows a state in which the power converters 31 to 33 constituting the power converter 30 (see FIG. 4) or the power converter 40 (see FIG. 5) are connected to different systems. And the state connected to the low voltage battery 46 is shown.

  In any of these cases, the present invention is effective, and a normal overheat protection operation can be performed.

  The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

  For example, in the above embodiment, the case where the power conversion device is configured by two or three power conversion units has been described as an example, but the number of power conversion units included in the power conversion device according to the present invention is two. If it is more, it will not specifically limit.

It is a schematic diagram which shows the structure of the power converter device 10 by preferable 1st Embodiment of this invention. 3 is a flowchart for explaining a method for setting an overheat protection temperature for the power converter 10; It is a schematic diagram which shows the structure of the power converter device 20 by preferable 2nd Embodiment of this invention. It is a schematic diagram which shows the structure of the power converter device 30 by preferable 3rd Embodiment of this invention. It is a schematic diagram which shows the structure of the power converter device 40 by preferable 4th Embodiment of this invention. It is a block diagram which shows roughly the principal part of the motor vehicle provided with the power converter device by this invention. It is a block diagram which shows the state which connected the power converters 11 and 12 which comprise the power converter device 10 or the power converter device 20 in parallel. It is a block diagram which shows the state which connected the power converters 31-33 which comprise the power converter device 30 or the power converter device 40 in parallel. It is a block diagram which shows the state which connected the power converters 11 and 12 which comprise the power converter device 10 or the power converter device 20 to the electric equipment 42 and the low voltage battery 46 of a different system, respectively. It is a block diagram which shows the state which connected the power converters 31 and 32 and the power converter 33 which comprise the power converter device 30 or the power converter device 40 to the electric equipment 42 and the low voltage battery 46 of a different system, respectively. It is a block diagram which shows the state which connected the power converters 31-33 which comprise the power converter device 30 or the power converter device 40 to the electric equipment 42 and the low voltage battery 46 of a different system, respectively.

Explanation of symbols

10, 20, 30, 40 Power conversion device 11, 12, 31-33 Power conversion unit 11a, 12a, 31a-33a Main circuit unit 11b, 12b, 31b-33b Temperature sensor 11c, 12c, 31c-33c Overheat detection unit 11d , 11e, 12d, 12e, 31d, 31e, 32d, 32e, 32f, 33d, 33e Setting unit 19 Cooling mechanism 19a Refrigerant 41 High-voltage battery 42 Electric equipment 43 Power generation device 44 Motor 45 Drive system 46 Low-voltage battery S Switching signal

Claims (13)

  A power conversion device comprising a plurality of power conversion units including at least a first and a second power conversion unit, wherein the second power conversion unit is based on the presence or absence of an overheat protection operation of the first power conversion unit. An overheat protection set value for the power converter is changed.   The power converter according to claim 1, wherein the first and second power converters are arranged adjacent to each other.   The cooling mechanism provided in common with respect to the plurality of power converters is further provided, and the overheat protection set value is determined based on a temperature of a refrigerant used in the cooling mechanism. The power converter according to 1 or 2.   4. The overheat protection set value of the second power conversion unit is lowered in response to the first power conversion unit shifting from a normal operation to an overheat protection operation. 5. The power converter device of Claim 1.   5. The power according to claim 4, wherein the second overheat protection set value is lowered after a predetermined time has elapsed since the first power conversion unit shifted from the normal operation to the overheat protection operation. Conversion device.   The overheat protection set value of the second power conversion unit is lowered stepwise or continuously in response to the first power conversion unit shifting from a normal operation to an overheat protection operation. Item 6. The power conversion device according to Item 4 or 5.   The overheat protection set value of the first power conversion unit is changed based on the presence or absence of an overheat protection operation of the second power conversion unit, according to any one of claims 1 to 6. Power conversion device.   The overheat protection set value of the first power conversion unit is held constant regardless of the presence or absence of the overheat protection operation of the second power conversion unit. The power converter described.   Each of the plurality of power conversion units includes a temperature sensor, and the influence of heat that the first power conversion unit has on the temperature sensor of the second power conversion unit is determined by the second power conversion unit. The power conversion device according to claim 8, wherein the power conversion device is larger than an influence of heat on a temperature sensor of one power conversion unit.   The power conversion device according to claim 1, wherein at least some of the plurality of power conversion units are connected so as to be capable of parallel operation.   The power converter according to any one of claims 1 to 10, wherein each of the plurality of power converters is a DC / DC converter. An overheat protection temperature setting method for a power conversion device including a plurality of power conversion units including at least first and second power conversion units,
In a state where at least the first and second power conversion units are normally operated, the temperature of the refrigerant used in the cooling mechanism provided in common for the plurality of power conversion units reaches a set temperature. An output value of a temperature sensor provided in the first power conversion unit is set as a first overheat protection set value of the first power conversion unit,
In the state where at least the first power conversion unit is normally operated and the second power conversion unit is overheat protected, the first power conversion unit when the temperature of the refrigerant reaches the set temperature An overheat protection temperature setting method for a power converter, wherein an output value of a provided temperature sensor is set as a second overheat protection set value of the first power converter. The output value of the temperature sensor provided in the second power conversion unit when the temperature of the refrigerant reaches the set temperature in a state where the first and second power conversion units are normally operated, Set as the first overheat protection set value of the second power converter,
In the state where at least the second power conversion unit is normally operated and the first power conversion unit is overheat protected, the second power conversion unit when the temperature of the refrigerant reaches the set temperature The method of setting an overheat protection temperature for a power converter according to claim 12, wherein an output value of the provided temperature sensor is set as a second overheat protection set value of the second power converter.

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