JP2020078168A - Power converter - Google Patents

Abstract

To provide a technique for preventing the temperature of each reactor from becoming excessively high for a power converter having two voltage converter circuits connected in parallel, each of which has a reactor.SOLUTION: A power converter 10 includes a first voltage converter having a first reactor, a second voltage converter having a second reactor, and a controller. The controller controls the first and second voltage converters so that when the temperature of the first reactor is above a first temperature threshold and the temperature of the second reactor is below a second temperature threshold, the current flowing in the second reactor is more than the current flowing in the first reactor. The controller controls the first and second voltage converters so that when the temperature of the second reactor is above the second temperature threshold and the temperature of the first reactor is below the first temperature threshold, the current flowing in the first reactor is more than the current flowing in the second reactor.SELECTED DRAWING: Figure 2

Description

  The technique disclosed in this specification relates to a power converter. In particular, it relates to a power converter in which a first voltage converter and a second voltage converter each including a reactor are connected in parallel.

  Patent Document 1 discloses a power converter including a plurality of reactors. Since the reactor generates a large amount of heat, multiple reactors are in contact with the cooler. In the power converter of Patent Document 1, the reactor having a large heat generation amount is arranged on the upstream side of the refrigerant with respect to the reactor having a small heat generation amount. Further, Patent Document 2 discloses a technique in which a flexible heat dissipation sheet is sandwiched between a reactor coil and a cooler in order to efficiently cool the reactor.

JP, 2005-180118, A JP, 2007-129146, A

  In the power converter in which each of the two reactors is used in the voltage converter and the two voltage converters are connected in parallel, the present specification appropriately describes that the temperature of each reactor becomes excessively high. Technology to suppress

  The power converter which this specification discloses is provided with the 1st voltage converter which has the 1st reactor, the 2nd voltage converter which has the 2nd reactor, and the controller. The first voltage converter and the second voltage converter are connected in parallel. The controller controls the first voltage converter and the second voltage converter. When the temperature of the first reactor is above the first temperature threshold and the temperature of the second reactor is below the second temperature threshold, the controller causes the current flowing through the second reactor to be larger than the current flowing through the first reactor. The first and second voltage converters are controlled so that When the temperature of the second reactor exceeds the second temperature threshold and the temperature of the first reactor is lower than the first temperature threshold, the controller causes the current flowing through the first reactor to be larger than the current flowing through the second reactor. The first and second voltage converters are controlled so that By controlling as described above, it is possible to appropriately suppress the temperature of each reactor from becoming excessively high.

  The power converter disclosed in the present specification is arranged adjacent to the cooler facing the first reactor with the heat dissipation sheet sandwiched between the cooler and the second reactor, and arranged away from the second reactor. Other parts may be provided. The heat resistant temperature of the other component is lower than the heat resistant temperature of the first reactor. The other parts are not limited to electrical parts.

  Since it is possible to prevent the temperature of the first reactor from becoming excessively high, it is possible to suppress the protrusion of the heat dissipation sheet (the protrusion from between the reactor and the cooler) due to the thermal expansion of the first reactor. At the same time, heat damage to other parts can be suppressed. For example, at the conventional reached temperature of the reactor, a component such as a capacitor having a lower heat resistant temperature than the reactor cannot be arranged adjacent to the reactor. The technique disclosed in the present specification has made it possible to suppress the temperature reached by the reactor to a low level, and thus it has become possible to dispose a component such as a capacitor having a lower heat resistant temperature than the reactor adjacent to the reactor. Details of the technology disclosed in the present specification and further improvements will be described in “Mode for Carrying Out the Invention” below.

1 is a block diagram of an electric vehicle including a power converter according to an embodiment. It is a flow chart of control which a controller performs. It is sectional drawing which shows the components arrangement | positioning inside the case of a power converter (1). It is sectional drawing which shows the components arrangement | positioning inside the case of a power converter (2).

  A power converter 10 according to an embodiment will be described with reference to the drawings. The power converter 10 is a device that is mounted on an electric vehicle and converts DC power of a battery into drive power of a traveling motor. FIG. 1 shows a block diagram of an electric vehicle 100 including a power converter 10.

  As described above, the power converter 10 is a device that converts the power of the battery 3 into the drive power of the two traveling motors 19a and 19b. The power converter 10 includes two voltage converters 11a and 11b, two inverters 6a and 6b, and capacitors 4 and 5.

  The two voltage converters 11a and 11b are connected in parallel between a common low-voltage end 8 (low-voltage positive end 8a, low-voltage negative end 8b) and a common high-voltage end 9 (high-voltage positive end 9a, high-voltage negative end 9b). Has been done. The capacitor 4 is connected between the low-voltage positive electrode end 8a and the low-voltage negative electrode end 8b. The capacitor 5 is connected between the high voltage positive electrode end 9a and the high voltage negative electrode end 9b. The capacitors 4 and 5 are provided to suppress voltage pulsation (or current pulsation) of electric power input to and output from the voltage converters 11a and 11b.

  The voltage converters 11a and 11b have the same structure, and have a boosting function of boosting the DC power input to the low voltage end 8 and outputting the boosted DC power from the high voltage end 9, and stepping down the DC power input to the high voltage end 9. And has a step-down function of outputting from the low voltage end 8. That is, the voltage converters 11a and 11b are bidirectional DC-DC converters.

  Two inverters 6a and 6b are connected in parallel to the high voltage end 9. Illustration of the circuit configuration of the inverters 6a and 6b is omitted. The inverter 6a (6b) converts the DC power supplied from the voltage converters 11a and 11b into AC power suitable for driving the motor 19a (19b). The converted AC power is supplied to the motor 19a (19b). Although not shown, the output shafts of the motors 19a and 19b are connected to the axle via a gear set.

  The motors 19a and 19b can output drive torque using electric power, and can also generate electric power using inertial energy of the vehicle. The electric power (regenerative electric power) generated by the motors 19a and 19b is converted from alternating current to direct current by the inverters 6a and 6b and supplied to the voltage converters 11a and 11b.

  The circuit configuration of the voltage converter 11a will be described. The voltage converter 11a includes two switching elements 13a and 14a, two diodes 15a and 16a, a reactor 12a, and a temperature sensor 17a. The two switching elements 13a and 14a are connected in series between the high voltage positive electrode end 9a and the high voltage negative electrode end 9b. The switching element 13a is located on the side closer to the high-voltage positive electrode end 9a, and the switching element 14a is located on the side closer to the high-voltage negative electrode end 9b.

  A diode 15a (16a) is connected in antiparallel to the switching element 13a (14a). The reactor 12a is connected between the midpoint of the series connection of the switching elements 13a and 14a and the low voltage positive electrode end 8a. The temperature sensor 17a is arranged near the reactor 12a and measures the temperature of the reactor 12a.

  The switching element 13a and the diode 16a are mainly involved in the step-down operation, and the switching element 14a and the diode 15a are mainly involved in the step-up operation. The switching elements 13a and 14a are controlled by the controller 7. The controller 7 receives the target voltage ratio of the voltage of the low voltage end 8 and the voltage of the high voltage end 9 from a host controller (not shown), and controls the switching elements 13a and 14a so that the target voltage ratio is realized. The switching elements 13a and 14b are driven by a PWM signal having a predetermined duty ratio. The controller 7 determines the duty ratio so that the target voltage ratio is realized. The controller 7 generates a drive signal (PWM signal) so that the switching element 14a is turned off when the switching element 13a is turned on, and the switching element 13a is turned off when the switching element 14a is turned on. Supply to 13a and 14a. Then, depending on the balance between the voltage of the low voltage end 8 and the voltage of the high voltage end 9, boosting and high voltage are passively switched. When the duty ratio of the switching element 14a involved in step-up is increased and the duty ratio of the switching element 13a involved in step-down is reduced, the voltage ratio between the low voltage end 8 and the high voltage end 9 becomes large.

  Since the circuit configuration of the voltage converter 11b is the same as that of the voltage converter 11a, detailed description thereof will be omitted. As is apparent from FIG. 1, the voltage converter 11b will be described by changing the suffix "a" of the reference numeral to "b" in the above description of the voltage converter 11a.

  The output of the battery 3 is several tens of kilowatts, and when such a large electric power flows, the reactors 12a and 12b generate heat and the temperature rises. In order to prevent the temperatures of the reactors 12a and 12b from becoming excessively high, the controller 7 adjusts the sharing ratios of the currents flowing through the voltage converters 11a and 11b in accordance with the temperatures of the reactors 12a and 12b. The current flowing through the voltage converter 11a (reactor 12a) is adjusted by adjusting the duty ratios of the switching elements 13a, 14a, 13b, 14b so that the voltage ratio of the voltage converter 11a is slightly higher than the voltage ratio of the voltage converter 11b. Is larger than the current flowing through the voltage converter 11b (reactor 12b). Conversely, by adjusting the duty ratios of the switching elements 13a, 14a, 13b, 14b so that the voltage ratio of the voltage converter 11b is slightly higher than the voltage ratio of the voltage converter 11a, the voltage converter 11b (reactor 12b). Is greater than the current flowing through the voltage converter 11a (reactor 12a).

  The measurement data of the temperature sensors 17a and 17b is sent to the controller 7. The controller 7 adjusts the sharing ratio of the current flowing through the voltage converters 11a and 11b according to the temperatures of the reactors 12a and 12b measured by the temperature sensors 17a and 17b.

  FIG. 2 shows a flowchart of the current sharing ratio adjustment processing executed by the controller 7. The process of FIG. 2 is periodically executed during traveling. Hereinafter, for convenience of description, the voltage converter 11a is referred to as a first voltage converter 11a, and the voltage converter 11b is referred to as a second voltage converter 11b. Further, the reactor 12a is referred to as a first reactor 12a, and the reactor 12b is referred to as a second reactor 12b. The symbol “DDC” in FIG. 2 means “voltage converter”.

  The controller 7 first acquires the temperature TR1 of the first reactor 12a and the temperature TR2 of the second reactor 12b from the temperature sensors 17a and 17b (step S2). When the temperature TR1 of the first reactor 12a exceeds the predetermined first temperature threshold value TRth1 and the temperature TR2 of the second reactor 12b is below the predetermined second temperature threshold value TRth2, the controller 7 determines that the second The first and second voltage converters 11a, 11b (that is, the switching elements 13a, 14a, 13b, 14b) are controlled so that the current flowing through the voltage converter 11b is larger than the current flowing through the first voltage converter 11a (steps). S3: YES, S4). As described above, by setting the voltage ratio of the second voltage converter 11b to be slightly higher than the voltage ratio of the first voltage converter 11a, more current is supplied to the second voltage converter 11b than to the first voltage converter 11a. Can be drained. As a result, the current flowing through the second reactor 12b becomes larger than the current flowing through the first reactor 12a.

  The first temperature threshold value TRth1 is set to a value obtained by subtracting a predetermined safety margin from the heat resistant upper limit temperature of the first reactor 12a. The second temperature threshold value TRth2 is set to a value obtained by subtracting a predetermined safety margin from the heat resistant upper limit temperature of the second reactor 12b.

  On the other hand, when the temperature TR2 of the second reactor 12b exceeds the second temperature threshold value TRth2 and the temperature TR1 of the first reactor 12a falls below the first temperature threshold value TRth1, the controller 7 determines that the first voltage converter The first and second voltage converters 11a and 11b (that is, the switching elements 13a, 14a, 13b, and 14b) are controlled so that the current flowing through 11a becomes larger than the current flowing through the second voltage converter 11b (step S5: YES, S6). As a result, the current flowing through the first reactor 12a becomes larger than the current flowing through the second reactor 12b.

  When both the condition of step S3 and the condition of step S5 are NO, the controller 7 controls the first and second voltages so that the current flowing through the first voltage converter 11a and the current flowing through the second voltage converter 11b become equal. The converters 11a, 11b (that is, the switching elements 13a, 14a, 13b, 14b) are controlled (steps S3: NO, S5: NO, S7). Then, the current flows equally in the first reactor 12a and the second reactor 12b.

  The effects of the above processing are as follows. When the temperature TR1 of the first reactor 12a is high (TR1> TRth1) and the second reactor 12b has a margin of temperature (TR2 <TRth2), the controller 7 determines the second voltage converter 11b (that is, the second voltage converter 11b). A large amount of current is passed through the second reactor 12b) to suppress the temperature rise of the first reactor 12a. On the contrary, when the temperature TR2 of the second reactor 12b is high (TR2> TRth2) and the first reactor 12a has a margin of temperature (TR1 <TRth1), the controller 7 has the first voltage converter 11a. (That is, a larger amount of current is passed through the first reactor 12a) to suppress the temperature rise of the second reactor 12b. By the process of FIG. 2, it is possible to prevent the temperatures of the first reactor 12a and the second reactor 12b from becoming excessively high.

  When the temperature TR1 of the first reactor 12a is higher than the first temperature threshold value TRth1 and the temperature TR2 of the second reactor 12b is higher than the second temperature threshold value TRth2, the controller 7 controls the first voltage converter 11a. The switching elements 13a, 14a, 13b, 14b are controlled so that the flowing current becomes equal to the current flowing through the second voltage converter 11b.

  The hardware structure of the power converter 10 will be described. FIG. 3 shows a cross-sectional view in which one side plate of the case of the power converter 10 is cut. FIG. 4 shows a cross-sectional view obtained by cutting another side plate of the case. FIG. 3 is equivalent to the cross section obtained by cutting the side plate on the + Y side in the coordinate system of FIG. FIG. 4 corresponds to a cross section obtained by cutting the side plate on the −X side in the coordinate system of FIG.

  The case 21 houses a stacked body of a plurality of coolers 32 and a plurality of semiconductor modules 33, a substrate 31, a first reactor 12a, a second reactor 12b, a cooler 34, a capacitor module 36, and a voltage converter 37. In FIG. 3, reference numeral 32 is attached only to the two leftmost coolers, and reference numerals are omitted for the other coolers in the stack. Similarly, the reference numeral 33 is attached only to the leftmost semiconductor module, and the reference numerals are omitted for the other semiconductor modules in the stacked body.

  Although not shown in FIG. 1, the voltage converter 37 is a device that steps down the voltage of the battery 3 and supplies it to an auxiliary battery (not shown). In FIG. 4, the voltage converter 37 is drawn by an imaginary line so that the second reactor 12b located on the rear side can be seen.

  Each of the plurality of semiconductor modules 33 accommodates two switching elements and two diodes. The main body of the semiconductor module 33 is a resin package, and the two switching elements are connected in series inside the package. Diodes are connected in antiparallel to the respective switching elements inside the package.

  One semiconductor module 33 houses the switching elements 13a and 14a and the diodes 15a and 16b of FIG. 1, and another semiconductor module 33 houses the switching elements 13b and 14b and the diodes 15b and 16b. The remaining semiconductor module 33 houses the switching elements (not shown) of the inverters 6a and 6b.

  A control terminal 39 extends from each of the plurality of semiconductor modules 33, and the control terminal 39 is connected to the substrate 31. The circuit that constitutes the controller 7 shown in FIG. 1 is mounted on the board 31, and the switching elements inside the semiconductor module 33 are controlled from the board 31 through the control terminals 39.

  In the semiconductor module 33, power terminals connected to the high-potential end, the midpoint, and the low-potential end of the series connection of the internal switching elements extend, but the illustration thereof is omitted. A bus bar that connects each power terminal to another device is also not shown. For example, the bus bar that connects the midpoint of the series connection of two switching elements and the reactor is not shown.

  The first reactor 12a faces the cooler 34 with the heat dissipation sheet 35 interposed therebetween. The cooler 34 is fixed to the partition plate 22 of the case 21. As shown in FIG. 4, the capacitor module 36 is located adjacent to the first reactor 12a. A plurality of capacitor elements are housed inside the capacitor module 36. Some of the capacitor elements correspond to the capacitor 4 of FIG. 1, and the remaining capacitor elements correspond to the capacitor 5 of FIG.

  The second reactor 12b is fixed to the bottom surface 23 of the case 21. The cooler does not touch the second reactor 12b, and the second reactor 12b is arranged at a position far from the condenser module 36.

  In the case of the above hardware configuration, the temperature of the first reactor 12a is prevented from becoming excessively high, so that the heat dissipation sheet 35 is extruded due to the thermal expansion of the first reactor 12a (of the first reactor 12a and the cooler 34). (Protrusion from the gap) can be suppressed. Further, heat damage to the capacitor module 36 adjacent to the first reactor 12a can be suppressed. The capacitor module 36 has a lower heat resistance temperature than the first reactor 12a. In the conventional technique, the capacitor module 36 cannot be arranged adjacent to the first reactor 12a. By controlling the temperature of the first reactor 12a from becoming excessively high by the above-described control, the capacitor module 36 having a low heat resistant temperature can be arranged adjacent to the first reactor 12a.

  The hardware configuration shown in FIGS. 3 and 4 is an example of the technology disclosed in this specification. However, in the case of having the hardware configuration of FIG. 3 and FIG. 4, the controller 7 has the temperature TR2 of the second reactor 12b> the second temperature threshold value TRth2 and the temperature TR1 of the first reactor 12a <the first When the temperature threshold TRth1 is satisfied but the temperature TR1 of the first reactor 12a is increasing, the current flowing through the first voltage converter 11a (first reactor 12a) and the second voltage converter 11b (second reactor 12b) is The switching elements 13a, 14a, 13b, 14b may be controlled to be equal. If the first reactor 12a is in contact with the cooler 34 and the second reactor 12b is not in contact with the cooler, the above condition cannot be normally established. When the above conditions are satisfied, there is a possibility that an abnormality has occurred in the temperature sensor or the current sensor. In such a case, it is desirable to make the current flow equally through the first reactor 12a and the second reactor 12b.

  Points to be noted regarding the technique described in the embodiment will be described. The component layout shown in FIGS. 3 and 4 is an example. The technology disclosed in the present specification is directed to a cooler that faces the first reactor with a heat dissipation sheet sandwiched between the cooler and another cooler that is arranged adjacent to the first reactor and apart from the second reactor. It can be applied to a power converter provided with an electric component.

  In step S3 of the flowchart of FIG. 2, TR1> TRth1 may be set to TR1 ≧ TRth1. Alternatively, conversely, TR2 <TRth2 may be set to TR2 ≦ TRth2. Similarly, in step S5, TR2> TRth2 may be set to TR2 ≧ TRth2, or conversely, TR1 <TRth1 may be set to TR1 ≦ TRth1.

  The component arranged adjacent to the first reactor 12a is not limited to the capacitor module 36. The components arranged adjacent to the first reactor 12a are not limited to electrical components. The component arranged adjacent to the first reactor 12a may be a component having a lower heat resistance temperature than the reactor 12a, or may be a component having a higher heat resistance temperature than the reactor 12a.

  Specific examples of the present invention have been described above in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in the present specification or the drawings exert technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technique illustrated in the present specification or the drawings can achieve a plurality of purposes at the same time, and achieving one of the purposes has technical utility.

3: Battery 4, 5: Capacitors 6a, 6b: Inverter 7: Controller 10: Power converters 11a, 11b: Voltage converters 12a, 12b: Reactors 13a, 13b, 14a, 14b: Switching elements 15a, 15b, 16a, 16b: Diodes 17a, 17b: Temperature sensors 19a, 19b: Motor 21: Case 22: Partition plate 23: Bottom surface 31: Substrates 32, 34: Cooler 33: Semiconductor module 35: Heat dissipation sheet 36: Capacitor module 37: Voltage converter 100: Electric car

Claims (2)

A first voltage converter having a first reactor;
A second voltage converter having a second reactor and connected in parallel to the first voltage converter;
A controller for controlling the first voltage converter and the second voltage converter;
Is equipped with
The controller is
When the temperature of the first reactor exceeds the first temperature threshold and the temperature of the second reactor is lower than the second temperature threshold, the current flowing through the second reactor is lower than the current flowing through the first reactor. Controlling the first and second voltage converters to increase
When the temperature of the second reactor exceeds the second temperature threshold and the temperature of the first reactor is lower than the first temperature threshold, the current flowing through the first reactor is the current flowing through the second reactor. A power converter that controls the first and second voltage converters so as to be more than the above. A cooler facing the first reactor with a heat dissipation sheet sandwiched between them;
A component that is arranged adjacent to the first reactor and is arranged apart from the second reactor, and has heat resistance lower than that of the first reactor,
The power converter according to claim 1, further comprising:

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