Power conversion device

Abstract

To prevent failure due to temperature rise of a semiconductor switching element at the time of all-phase short circuit.SOLUTION: A temperature detection unit configured to detect a temperature of at least one of the upper arm-side semiconductor switching element and the lower arm-side semiconductor switching element, and a controller configured to perform ON / OFF control of the upper arm-side semiconductor switching element and the lower arm-side semiconductor switching element, wherein the controller is configured to control the upper arm-side semiconductor switching element and the lower arm-side semiconductor switching element by determining whether to perform all phase short circuit control of turning on all the upper arm-side semiconductor switching elements or all the lower arm-side semiconductor switching elements of each phase and turning off all the semiconductor switching elements on an opposite side, based on a detected temperature of the temperature detection unit.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a power conversion device. [Background technology]

[0002] In a power conversion device that performs power conversion between DC and AC, series circuits in which upper arm semiconductor switching elements and lower arm semiconductor switching elements are connected in series are connected in parallel for the number of phases. In the case of an abnormality in the power conversion device or the load, there is a power conversion device that performs all-phase short-circuit control in which semiconductor switching elements of all phases in one of the upper and lower arms are brought into a conducting state and semiconductor switching elements of all phases in the other arm are brought into a cutting state (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-198139 A Summary of the Invention [Problem to be solved by the invention]

[0004] The power conversion device disclosed in Patent Document 1 can avoid failure of the power conversion device by performing an all-phase short circuit when an abnormality occurs in the power conversion device or the load. However, when an all-phase short circuit is performed, a large current flows through the semiconductor switching elements of the arm that is in a conductive state, and if the temperature of the semiconductor switching elements is high immediately before the all-phase short circuit is performed, the heat generated by the all-phase short circuit will further increase the temperature of the semiconductor switching elements, causing a failure.

[0005] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a power conversion device that prevents a semiconductor switching element from failing due to a temperature rise when all phases are short-circuited. [Means for solving the problem]

[0006] The power conversion device of the present disclosure is a power conversion device in which series bodies of upper arm side semiconductor switching elements and lower arm side semiconductor switching elements are connected in parallel in the same number as the number of AC phases, the connection points of the upper arm side semiconductor switching elements and the lower arm side semiconductor switching elements of each series body become AC terminals for each AC phase, the series bodies connected in parallel are connected between the positive side and negative side of a DC voltage, and the power conversion device converts power between the DC side and the AC side, and further includes a temperature detection unit that detects the temperature of at least one of the upper arm side semiconductor switching elements or the lower arm side semiconductor switching elements, and a temperature detection unit that detects the temperature of the upper arm side semiconductor switching elements and the lower arm side semiconductor switching elements. and a controller that controls the on / off of the upper-arm-side semiconductor switching elements and the lower-arm-side semiconductor switching elements, and the controller is configured to determine, based on the temperature detected by the temperature detection unit, whether to perform all-phase short-circuit control in which all of the upper-arm-side semiconductor switching elements of each phase are turned on and all of the lower-arm-side semiconductor switching elements are turned off, or all-phase short-circuit control in which all of the lower-arm-side semiconductor switching elements of each phase are turned on and all of the upper-arm-side semiconductor switching elements of each phase are turned off, and to control the upper-arm-side semiconductor switching elements and the lower-arm-side semiconductor switching elements. [Effects of the Invention]

[0007] According to the power conversion device of the present disclosure, it is possible to provide a power conversion device that can prevent a semiconductor switching element from failing due to a temperature rise when all phases are short-circuited. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a circuit diagram showing a configuration of a power conversion device according to a first embodiment. [Figure 2] 1 is a schematic diagram showing a configuration of a power module of a power conversion device according to a first embodiment. [Figure 3] 4 is a process flow diagram showing the operation of the power conversion device according to the first embodiment. FIG. [Figure 4]FIG. 10 is a schematic diagram showing the configuration of a power module of a power conversion device according to a second embodiment. [Figure 5] FIG. 10 is a process flow diagram showing the operation of the power conversion device according to the second embodiment. [Figure 6] FIG. 10 is a schematic diagram showing the configuration of a power module of a power conversion device according to a third embodiment. [Figure 7] FIG. 11 is a process flow diagram showing the operation of the power conversion device according to the third embodiment. [Figure 8] FIG. 11 is a process flow diagram showing another operation of the power conversion device according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] The power conversion device disclosed in Patent Document 1 can avoid a failure by short-circuiting all phases when an abnormality occurs. This indicates that short-circuiting all phases is a state in which a failure can be avoided regardless of the operating state. The inventors have studied the use of short-circuiting all phases in a power conversion device when there is no drive command before startup.

[0010] Consider the case where the load of the power conversion device is a motor that drives a vehicle. Before startup, when no control is performed, all semiconductor switching elements in the upper and lower arms are in the off state, a so-called all-phase shutdown. Even in the all-phase shutdown state, since the semiconductor switching elements are connected in parallel with freewheeling diodes, if the motor is rotating at startup, an electromotive force is generated in the motor by the rotating magnet. If this voltage is higher than the voltage applied to the DC side of the power conversion device, the motor will enter a power generation state, resulting in unintended charging. In this case, power generation can be avoided by short-circuiting all phases.

[0011] It is known that an all-phase short circuit generates braking torque at lower motor rotation speeds than an all-phase interruption. This braking torque can be used to prepare for vehicle brake failure. It is desirable to keep all phases short-circuited after the ignition is turned on and the power conversion device is started, so that the vehicle can be prevented from moving due to external forces as quickly as possible. When starting up a power conversion device, the operating state prior to that point is unknown, and it is unclear whether the temperature within the module has been equalized. Therefore, we investigated detecting the temperature of the semiconductor switching elements within the module and performing all-phase short-circuit control only when the temperature is high enough to determine that no failure will occur even if all-phase short-circuiting is performed.

[0012] Semiconductor switching elements used in power converters include those with multiple switching elements built into a single power module (package) for enhanced convenience. This power module typically includes a series combination of upper and lower arm semiconductor switching elements and is used in power converters that convert power between DC and AC. In this configuration, the series combination is connected between the P terminal, which connects to the positive side of a DC power supply, and the N terminal, which connects to the negative side of the DC power supply. The junction between the upper and lower arms serves as an AC terminal for connecting to a load, such as an AC motor. As most motors are three-phase, three-wire systems, multiple power modules are often connected in parallel. For ease of use, the P and N terminals of the power module are located on the same short end face, the AC terminal on the opposite short end face, and no terminals are located on the long end face. This allows multiple power modules to be arranged side by side with their long end faces facing each other, and their P and N terminals connected to form a parallel connection.

[0013] Because semiconductor switching elements can fail if their temperature exceeds a certain threshold, some conventional power modules are equipped with temperature detectors to measure their temperature. Conventional power modules typically have temperature detectors on both the upper and lower arm sides, but to reduce costs, we are considering a configuration with a temperature detector on only one side. Such low-cost power modules require selective temperature detection on either the upper or lower arm side. However, because the upper and lower arms are physically separated, we discovered that there is a problem of temperature unevenness, where the temperature on the upper and lower arms differs depending on the current flow path or heat transfer path.

[0014] As mentioned above, different current paths generate different amounts of heat. However, during full-phase short-circuit control, current flows between the power converter and the motor to dissipate the electromotive force generated in the coil, resulting in conduction loss, which is the most prominent case. Therefore, if a full-phase short circuit causes current to continue to flow through the arm without a temperature detection unit, the temperature may not be uniform and exceed the specified temperature, potentially leading to a breakdown. Below, we will explain the configuration of a power converter that can prevent breakdowns even in such cases.

[0015] Embodiment 1 The first embodiment will be described with reference to the drawings. Hereinafter, the same or corresponding parts in each drawing will be described with the same reference numerals.

[0016] Fig. 1 is a circuit diagram showing the configuration of a power conversion device according to a first embodiment. Power conversion device 1 converts DC power from a power supply 8 into AC power and outputs it to a motor 9, which is a load, to provide driving force. In addition, in a regenerative mode, the rotational force of motor 9 is converted into AC power, which is used to charge power supply 8 through power conversion device 1. Positive terminal P and negative terminal N are terminals connected to power supply 8, and terminals U, V, and W are terminals connected to motor 9, which is a load. Terminals U, V, and W are collectively referred to as AC terminals.

[0017] Each of power module 2U, power module 2V, and power module 2W (the power modules may be collectively referred to as power module 2) has two internal semiconductor switching elements. Each power module has a P terminal and an N terminal connected to a power supply 8, and an AC terminal connected to a load. Power module 2U has an upper-arm semiconductor switching element 3U and a lower-arm semiconductor switching element 4U, power module 2V has an upper-arm semiconductor switching element 3V and a lower-arm semiconductor switching element 4V, and power module 2W has an upper-arm semiconductor switching element 3W and a lower-arm semiconductor switching element 4W. The upper-arm semiconductor switching elements may be collectively referred to as upper-arm semiconductor switching element 3, and the lower-arm semiconductor switching elements may be collectively referred to as lower-arm semiconductor switching element 4. The upper-arm semiconductor switching element 3 and the lower-arm semiconductor switching element 4 are connected in series, and the connection point is connected to an AC terminal provided on each power module. The other end of the upper-arm semiconductor switching element 3 is connected to terminal P, and the other end of the lower-arm semiconductor switching element 4 is connected to terminal N. Each power module is equipped with temperature detection units 5U, 5V, and 5W (the temperature detection units may be collectively referred to as temperature detection unit 5) to detect the temperature of the upper-arm semiconductor switching element 3. Current sensors 10U, 10V, and 10W (the current sensors may be collectively referred to as current sensor 10) detect the current flowing from the power module 2 to the motor 9. The controller power supply 7 supplies power to operate the controller 6 in conjunction with the vehicle ignition switch (not shown). Based on information from the temperature detection unit 5, the voltage value from a voltage detection unit (not shown), the rotation angle of the motor 9, and other information, the controller 6 controls the upper-arm semiconductor switching element 3 and the lower-arm semiconductor switching element 4 to turn on and off via control lines (not shown), thereby controlling the amount of current flowing to the motor 9 from the power supply 8.

[0018] FIG. 2 is a schematic diagram of a power module 2 according to a first embodiment. The structure of the power module 2 will be described using FIG. 2. Inside the power module 2, the upper-arm semiconductor switching elements 3 and the lower-arm semiconductor switching elements 4 are electrically connected in series between a P terminal 21 and an N terminal 22. The connection point between the upper-arm semiconductor switching elements 3 and the lower-arm semiconductor switching elements 4 is connected to an AC terminal 20. Thus, the power module 2 has a total of three terminals: the P terminal 21 connected to the positive terminal P of the power supply 8; the N terminal 22 connected to the negative terminal N of the power supply 8; and the AC terminal 20, which is the connection point between the upper-arm semiconductor switching elements 3 and the lower-arm semiconductor switching elements 4 and is connected to the motor 9 as a load. The power module 2 also has a temperature detection unit 5 that detects the temperature of the upper-arm semiconductor switching elements 3. The AC terminals of the power modules 2U, 2V, and 2W are connected to the terminals U, V, and W of FIG. 1, respectively.

[0019] The P terminal 21 and the N terminal 22 are arranged on the end face of the power module closer to the position where the lower arm semiconductor switching element 4 is arranged, and the AC terminal 20 is arranged on the end face closer to the position where the upper arm semiconductor switching element 3 is arranged. The P terminal 21 and the N terminal 22 are arranged with an insulating distance between them to prevent insulation. The power modules are arranged so that their longitudinal end faces face each other, and as shown in FIG. 1, they are assumed to be connected in parallel between the positive terminal P and the negative terminal N of the power supply 8, so no terminals are arranged on the longitudinal end faces. FIG. 2 also shows the P-side control terminal 23P, from which the control lines required to control the upper arm semiconductor switching element 3 are drawn, and the N-side control terminal 23N, from which the control lines required to control the lower arm semiconductor switching element 4 are drawn.

[0020] If one considers providing a temperature detection unit on either the upper arm semiconductor switching element 3 or the lower arm semiconductor switching element 4 to reduce costs, it would be difficult to ensure an insulating distance between the P terminal 21 and N terminal 22 that are already in place if one were to extract the signal from the temperature detection unit 5 from the lower end face in Fig. 2. On the other hand, because the upper end face only has the AC terminal 20, there is ample space, and it can be seen that there are certain advantages to extracting the signal line of the temperature detection unit 5 from the upper end face.

[0021] The power conversion device of the present disclosure is designed to perform an all-phase short circuit, in which all of the semiconductor switching elements of each phase on either the upper-arm semiconductor switching elements 3 or the lower-arm semiconductor switching elements 4 are turned on and shorted. While an all-phase short circuit is being performed, a current flows through either the upper-arm semiconductor switching elements 3 or the lower-arm semiconductor switching elements 4. In either case, a current flows through the AC terminal 20, causing heat generation at the AC terminal 20 due to conduction loss. This heat generation causes the upper-arm semiconductor switching elements 3 closer to the AC terminal 20 to absorb heat, and there is a high possibility that their temperature will rise during an all-phase short circuit. Therefore, a configuration in which the temperature detection unit 5 detects the temperature of the upper-arm semiconductor switching elements 3, i.e., the semiconductor switching elements arranged closer to the AC terminal 20, is preferable to a configuration in which the temperature detection unit 5 detects the temperature of the upper-arm semiconductor switching elements 3, i.e., the semiconductor switching elements arranged closer to the AC terminal 20, rather than a configuration in which the temperature detection unit 5 detects the temperature of the lower-arm semiconductor switching elements 4.

[0022] 3 is a process flow diagram showing the process of the power conversion device according to embodiment 1. The process flow starts, and in step S101, the controller power supply 7 is turned on by the ignition of a vehicle (not shown). At this point, no DC voltage is applied between terminals P and N from power supply 8.

[0023] In step S102, it is determined whether the temperature of the upper-arm semiconductor switching element 3 detected by the temperature detection unit 5 is equal to or higher than a predetermined temperature. If the temperature is equal to or higher than the predetermined temperature in any phase, the process proceeds to step S106 without short-circuiting all phases because short-circuiting all phases on the upper arm side may cause failure of the upper-arm semiconductor switching element with a higher temperature. In step S102, if the temperature detection value of the temperature detection unit 5 cannot be used for some reason, such as a failure of the temperature detection unit 5, the process proceeds to step S106 without short-circuiting all phases. In step S102, if the temperature is lower than the predetermined temperature in all phases, the process proceeds to step S103.

[0024] In step S103, the controller 6 executes all-phase short-circuit control to turn on the upper-arm semiconductor switching elements 3 of all phases and turn off the lower-arm semiconductor switching elements 4 of all phases, and then proceeds to step S106.

[0025] In step S106, the all-phase short circuit is terminated, and the power supply power source 8 is connected to the power conversion device 1, and a DC voltage is applied between the P terminal and the N terminal. In step S107, the switching elements proceed to normal control, and the all-phase short circuit processing flow is terminated.

[0026] The power conversion device according to the first embodiment is configured as described above. When an all-phase short circuit occurs, AC terminal 20 generates heat, and the resulting heat reception tends to increase the temperature of the upper-arm semiconductor switching elements arranged near AC terminal 20. Therefore, temperature detection unit 5 is arranged to detect the temperature of the upper-arm semiconductor switching elements. By arranging temperature detection unit 5 on the upper arm side, it is expected that the effects of heat reception by the upper-arm semiconductor switching elements when an all-phase short circuit is executed can be prevented in advance. Furthermore, because only the AC terminals are present on the end face on the upper arm side, terminal placement can be made with ample space in mind, taking insulation distance into consideration, resulting in a smaller power module.

[0027] In the power conversion device according to embodiment 1, there are cases where all phases are not short-circuited when the temperature of the semiconductor switching elements is high. When all phases are not short-circuited, the semiconductor switches are not brought into a conductive state, which has the advantage of preventing unintended upper and lower arm short-circuit failures when the upper or lower semiconductor switch has failed, and simplifying the control logic.

[0028] Embodiment 2 Fig. 4 is a schematic diagram showing the configuration of a power module of a power conversion device according to embodiment 2. As shown in Fig. 4, in embodiment 2, temperature detection unit 5 is arranged on the side of the lower arm semiconductor switching elements so as to detect the temperatures of the lower arm semiconductor switching elements. The overall configuration of the power conversion device according to embodiment 2 is the same as the configuration shown in Fig. 1 except for the positions of temperature detection units 5U, 5V, and 5W.

[0029] 5 is a process flow diagram showing the process of the power conversion device according to the embodiment 2. Steps S101, S106, and S107 are the same as those described in the embodiment 1.

[0030] In step S112, it is determined whether the temperature of the lower-arm semiconductor switching element 4 detected by the temperature detection unit 5 is equal to or higher than a predetermined temperature. If the temperature is equal to or higher than the predetermined temperature in any phase, the process proceeds to step S106 without short-circuiting all phases because short-circuiting all phases on the lower arm side may cause failure of the lower-arm semiconductor switching element with a higher temperature. In step S112, if the temperature detection value of the temperature detection unit 5 cannot be used for some reason, such as a failure of the temperature detection unit 5, the process proceeds to step S106 without short-circuiting all phases. In step S112, if the temperature is lower than the predetermined temperature in all phases, the process proceeds to step S113.

[0031] In step S113, the controller 6 performs all-phase short-circuiting by placing the lower-arm semiconductor switching elements 4 of all phases in a conducting state and the upper-arm semiconductor switching elements 3 of all phases in a cut-off state, and then proceeds to step S106.

[0032] In the power conversion device according to the second embodiment, the temperature detector 5 is positioned to detect the temperature of the lower-arm semiconductor switching elements. This arrangement allows the GND of the temperature detector 5 to be common with the N terminal and has the same potential as the housing, so that the signal line can be shielded to improve noise resistance. This allows for more accurate temperature measurement.

[0033] Embodiment 3 Fig. 6 is a schematic diagram showing the configuration of a power module of a power conversion device according to embodiment 3. As shown in Fig. 6, in this embodiment 3, a first temperature detection unit 51 is arranged on the upper arm semiconductor switching element 3 side and a second temperature detection unit 52 is arranged on the lower arm semiconductor switching element 4 side as temperature detection units so as to detect the temperatures of the upper arm semiconductor switching element 3 and the lower arm semiconductor switching element 4, respectively. The overall configuration of the power conversion device according to embodiment 3 is the same as that shown in Fig. 1 except for temperature detection units 5U, 5V, and 5W.

[0034] 7 is a process flow diagram showing the process of the power conversion device according to the embodiment 3. Steps S101, S106, and S107 are the same as those described in the embodiment 1.

[0035] In step S122, it is determined whether the temperature of the upper-arm semiconductor switching elements 3 detected by the first temperature detection unit 51 is equal to or higher than a predetermined temperature. If the temperature is below the predetermined temperature in all phases, the process proceeds to step S123. In step S123, the controller 6 executes all-phase short-circuiting, which places the upper-arm semiconductor switching elements 3 of all phases in a conductive state and the lower-arm semiconductor switching elements 4 of all phases in a cut-off state, and then proceeds to step S106. If the temperature is equal to or higher than the predetermined temperature in any phase, or if the temperature detection value of the first temperature detection unit 51 cannot be used for some reason, such as a failure of the first temperature detection unit 51, executing all-phase short-circuiting on the upper-arm side may cause failure of the upper-arm semiconductor switching elements, so the process proceeds to step S124 without executing all-phase short-circuiting on the upper-arm side.

[0036] In step S124, it is determined whether the temperature of the lower-arm semiconductor switching element 4 detected by the second temperature detection unit 52 is equal to or higher than a predetermined temperature. If the temperature is equal to or higher than the predetermined temperature in any phase, the process proceeds to step S106 without short-circuiting all phases because there is a risk of the lower-arm semiconductor switching element failing if all phases are short-circuited on the lower arm side. In step S124, if the temperature detection value of the temperature detection unit 5 cannot be used for some reason, such as a failure of the temperature detection unit 5, the process proceeds to step S106 without short-circuiting all phases. In step S124, if the temperature is lower than the predetermined temperature in all phases, the process proceeds to step S125.

[0037] In step S125, the controller 6 performs an all-phase short circuit by placing the lower-arm semiconductor switching elements 4 of all phases in a conducting state and the upper-arm semiconductor switching elements 3 of all phases in a cut-off state, and then proceeds to step S106.

[0038] In FIG. 7, the temperature on the upper arm side is determined first, but as shown in FIG. 8, the temperature on the lower arm side may be determined first in step S122, and the temperature on the upper arm side may be determined in step S124.

[0039] In the third embodiment, temperature detection units are arranged on the upper arm side and the lower arm side. When the temperature on the upper arm side is determined first, if the temperature on the upper arm side is below a predetermined temperature in all phases, all-phase short-circuiting is performed on the upper arm side. If the temperature on the upper arm side is equal to or higher than the predetermined temperature in any phase, all-phase short-circuiting is not performed on the upper arm side. If the temperature on the lower arm side is below the predetermined temperature in all phases, all-phase short-circuiting is performed on the lower arm side. Furthermore, when the temperature on the lower arm side is determined first, if the temperature on the lower arm side is below the predetermined temperature in all phases, all-phase short-circuiting is performed on the lower arm side. If the temperature on the lower arm side is equal to or higher than the predetermined temperature in any phase, all-phase short-circuiting is not performed on the lower arm side. If the temperature on the upper arm side is below the predetermined temperature in all phases, all-phase short-circuiting control is not performed on the lower arm side. Furthermore, if the temperature on the upper arm side is equal to or higher than the predetermined temperature in any phase and the temperature on the lower arm side is equal to or higher than the predetermined temperature in any phase, all-phase short-circuiting control is not performed. This makes it possible to broaden the range in which failures due to all-phase short-circuiting control can be avoided.

[0040] Although various exemplary embodiments and examples are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are contemplated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, and even cases where at least one component is extracted and combined with components of another embodiment. [Explanation of symbols]

[0041] 3, 3U, 3V, 3W upper arm side semiconductor switching element, 4, 4U, 4V, 4W lower arm side semiconductor switching element, 5, 5U, 5V, 5W temperature detection unit, 51 first temperature detection unit, 52 second temperature detection unit, 6 controller

Claims

1. A power conversion device for converting power between a DC side and an AC side, in which series elements of upper arm side semiconductor switching elements and lower arm side semiconductor switching elements are connected in parallel in the same number as the number of AC phases, a connection point between the upper arm side semiconductor switching element and the lower arm side semiconductor switching element of each series element becomes an AC terminal for each AC phase, and the series elements connected in parallel are connected between a positive side and a negative side of a DC voltage, a temperature detection unit that detects the temperature of at least one of the upper arm semiconductor switching element and the lower arm semiconductor switching element; a controller that controls the on / off of the upper arm semiconductor switching element and the lower arm semiconductor switching element, The controller determines, based on the temperature detected by the temperature detection unit, whether to perform all-phase short-circuit control in which all of the upper-arm semiconductor switching elements of each phase are turned on and all of the lower-arm semiconductor switching elements are turned off, or all-phase short-circuit control in which all of the lower-arm semiconductor switching elements of each phase are turned on and all of the upper-arm semiconductor switching elements of each phase are turned off, and controls the upper-arm semiconductor switching elements and the lower-arm semiconductor switching elements.

2. 2. The power conversion device according to claim 1, wherein, in a state in which a load is connected to the AC terminals and the DC voltage is not applied, the controller determines whether to perform the all-phase short-circuit control based on the temperature detected by the temperature detection unit, and controls the upper arm semiconductor switching elements and the lower arm semiconductor switching elements.

3. 3. The power conversion device according to claim 1, wherein the upper arm semiconductor switching element and the lower arm semiconductor switching element of each phase are arranged in one power module for each phase.

4. the temperature detection unit is configured to detect the temperature of the upper arm semiconductor switching element of each phase, when the temperatures detected by the temperature detection units are lower than a predetermined temperature in all phases, the controller performs the all-phase short-circuit control by turning on all of the upper-arm semiconductor switching elements of each phase and turning off all of the lower-arm semiconductor switching elements of each phase; When the temperature detected by the temperature detection unit is equal to or higher than a predetermined temperature in at least one phase, the all-phase short-circuit control is not performed. The power conversion device according to claim 1 or 2.

5. the temperature detection unit is configured to detect the temperature of the lower arm semiconductor switching element of each phase, When the temperature detected by the temperature detection unit is lower than a predetermined temperature in all phases, the controller performs the all-phase short-circuit control by turning on all of the lower-arm semiconductor switching elements of each phase and turning off all of the upper-arm semiconductor switching elements of each phase, and when the temperature detected by the temperature detection unit is equal to or higher than a predetermined temperature in at least one phase, the controller does not perform the all-phase short-circuit control. The power conversion device according to claim 1 or 2.

6. the temperature detection unit includes a first temperature detection unit that detects the temperature of the upper arm semiconductor switching element of each phase, and a second temperature detection unit that detects the temperature of the lower arm semiconductor switching element of each phase, when the temperatures detected by the first temperature detection units are lower than a predetermined temperature in all phases, the controller performs the all-phase short-circuit control by turning on all of the upper-arm semiconductor switching elements of each phase and turning off all of the lower-arm semiconductor switching elements of each phase; 3. The power conversion device according to claim 1, wherein when the temperature detected by the first temperature detection unit is equal to or higher than a predetermined temperature in at least one phase and the temperature detected by the second temperature detection unit is lower than the predetermined temperature in all phases, the all-phase short-circuit control is performed by turning on all of the lower-arm semiconductor switching elements of each phase and turning off all of the upper-arm semiconductor switching elements of each phase.

7. the temperature detection unit includes a first temperature detection unit that detects the temperature of the upper arm semiconductor switching element of each phase, and a second temperature detection unit that detects the temperature of the lower arm semiconductor switching element of each phase, when the temperatures detected by the second temperature detection units are lower than a predetermined temperature in all phases, the controller performs the all-phase short-circuit control by turning on all of the lower-arm semiconductor switching elements of each phase and turning off all of the upper-arm semiconductor switching elements of each phase; 3. The power conversion device according to claim 1, wherein when the temperature detected by the second temperature detection unit is equal to or higher than a predetermined temperature in at least one phase and the temperature detected by the first temperature detection unit is lower than the predetermined temperature in all phases, the all-phase short-circuit control is performed by turning on all of the upper-arm semiconductor switching elements of each phase and turning off all of the lower-arm semiconductor switching elements of each phase.

8. the temperature detection unit includes a first temperature detection unit that detects the temperature of the upper arm semiconductor switching element of each phase, and a second temperature detection unit that detects the temperature of the lower arm semiconductor switching element of each phase, 3. The power conversion device according to claim 1, wherein the controller does not perform the all-phase short-circuit control when the temperature detected by the first temperature detection unit is equal to or higher than a predetermined temperature in at least one phase and the temperature detected by the second temperature detection unit is equal to or higher than a predetermined temperature in at least one phase.

Images