JP6996403B2 - Power converter - Google Patents

Description

The techniques disclosed herein relate to power converters. In particular, it relates to a power conversion unit and a power converter equipped with a reactor.

Patent Document 1 discloses a power converter including a power conversion unit and a reactor. The power converter is installed in an electric vehicle. The power converter includes a boost converter circuit that boosts the DC power of the battery and an inverter circuit that converts the boosted DC power into AC power having a frequency suitable for driving the motor. The main components of the boost converter circuit and the inverter circuit are switching elements for power conversion. The boost converter circuit includes a reactor as another major component. In the power converter of Patent Document 1, a switching element for a boost converter circuit and a switching element for an inverter circuit are integrated in a power conversion unit.

When a large current flows, the reactor heats up. It is necessary to control the temperature of the reactor in order to pass as much current as possible to the boost converter circuit including the reactor while preventing the reactor from overheating. In the power converter of Patent Document 1, the temperature of the bus bar extending from the reactor is measured to obtain an approximate temperature of the reactor. In order to effectively use the space in the case of the power converter, the temperature sensor is provided in the sensor unit through which the output bus of the power conversion unit passes. The sensor unit has a current sensor that measures the current of the output bus bar. The signal line of the current sensor extends from the sensor unit to the control board that controls the switching element of the power conversion unit. The signal line of the temperature sensor also extends parallel to the signal line of the current sensor and is connected to the control board.

Japanese Unexamined Patent Publication No. 2017-093221

In order to accurately measure the temperature of the reactor, it is better to measure the temperature of the reactor itself, not the temperature of the bass bar extending from the reactor. The present specification provides a power converter in which a temperature sensor is provided in the reactor and the signal line of the temperature sensor is arranged.

The power converter disclosed herein is a power conversion unit that includes a case divided into a first case and a second case, a reactor equipped with a temperature sensor, and a plurality of switching elements for power conversion. It also has a sensor unit and a control board. The reactor is fixed to the first case. On the other hand, the power conversion unit, the sensor unit, and the control board are fixed to the second case. The sensor unit includes a current sensor that measures the current flowing through the output bus bar of the power conversion unit. The control board is connected to each of the current sensor unit and the power conversion unit by a signal line. The first case is provided with a connector hole for connecting an external cable to the output bus bar. The first signal line extending from the temperature sensor of the reactor and the second signal line conducting with the control board are connected at a position visible from the connector hole in the sensor unit.

In the power converter disclosed in the present specification, the reactor is fixed to the first case, and the control board to which the signal line of the temperature sensor is connected is fixed to the second case. Therefore, after connecting the first case and the second case, the temperature sensor and the control board must be connected. Therefore, in the power converter disclosed in the present specification, in the sensor unit fixed to the first case, the first signal line extending from the temperature sensor and the second signal conducting with the control board at a position visible from the connector hole. Connect the wires. Therefore, after connecting the first case and the second case, a tool can be inserted into the connector hole from the outside to connect the first signal line and the second signal line. Furthermore, since the second signal line that transmits the signal of the temperature sensor of the reactor is passed through the sensor unit, the second signal line can be combined with the bundle of the signal lines of the current sensor, so that the temperature sensor can be arranged. It will be easy.

Details and further improvements to the techniques disclosed herein will be described in the "Modes for Carrying Out the Invention" section below.

It is a circuit diagram of the power converter of 1st Embodiment. It is a side view of the power converter of 1st Embodiment. It is sectional drawing of the electric power converter which cut the side plate. It is sectional drawing of the power converter cut by the IV-IV line of FIG. It is sectional drawing of the power converter cut by the VV line of FIG. It is a circuit diagram of the power converter of the 2nd Example. It is sectional drawing of the electric power converter of the 2nd Example which cut the side plate.

(First Example) The power converter 2 of the first embodiment will be described with reference to the drawings. The power converter 2 is mounted on the electric vehicle 100. FIG. 1 shows a block diagram of an electric power system of an electric vehicle 100 including a power converter 2. The electric vehicle 100 of the embodiment includes traveling motors 83a and 83b. The power converter 2 is a device that converts the DC power of the battery 81 into the drive power of the traveling motors 83a and 83b. The outputs of the two traveling motors 83a and 83b are combined by the gearbox 85 and transmitted to the axle 86 (that is, the drive wheels).

The power converter 2 is connected to the battery 81 via the system main relay 82. The power converter 2 includes a voltage converter circuit 12 that boosts the voltage of the battery 81, and two sets of inverter circuits 13a and 13b that convert the boosted DC power into alternating current. The first inverter circuit 13a generates the driving power of the traveling motor 83a, and the second inverter circuit 13b generates the driving power of the traveling motor 83b.

The voltage converter circuit 12 boosts the voltage applied to the terminal on the battery side and outputs it to the terminal on the inverter side, and steps down the voltage applied to the terminal on the inverter side and outputs it to the terminal on the battery side. It is a bidirectional DC-DC converter capable of performing both step-down operations. For convenience of explanation, in the following, the terminal on the battery side (low voltage side) will be referred to as an input terminal 18, and the terminal on the inverter side (high voltage side) will be referred to as an output terminal 19. Further, the positive electrode and the negative electrode of the input end 18 are referred to as an input positive electrode end 18a and an input negative electrode end 18b, respectively. The positive electrode and the negative electrode of the output end 19 are referred to as an output positive electrode end 19a and an output negative electrode end 19b, respectively. The notations "input end 18" and "output end 19" are for convenience of explanation, and as described above, since the voltage converter circuit 12 is a bidirectional DC-DC converter, it is an output end. Power may flow from 19 to the input end 18.

The voltage converter circuit 12 is composed of a series circuit of two switching elements 9a and 9b, a reactor 7, a filter capacitor 5, and a diode connected in antiparallel to each switching element. One end of the reactor 7 is connected to the input positive electrode end 18a, and the other end is connected to the midpoint of the series circuit. The filter capacitor 5 is connected between the input positive electrode end 18a and the input negative electrode end 18b. The input negative electrode end 18b is directly connected to the output negative electrode end 19b. The switching element 9b is mainly involved in the step-up operation, and the switching element 9a is mainly involved in the step-down operation. Since the voltage converter circuit 12 of FIG. 1 is well known, detailed description thereof will be omitted. The circuit in the range of the broken line rectangle indicated by the reference numeral 8a corresponds to the power module 8a described later. Reference numerals 11a, 11b, and 11c indicate terminals extending from the power module 8a. Reference numeral 11a indicates a terminal (positive electrode terminal 11a) conducting with the positive electrode side of the series circuit of the switching elements 9a and 9b. Reference numeral 11b indicates a terminal (negative electrode terminal 11b) conducting with the negative electrode side of the series circuit of the switching elements 9a and 9b. Reference numeral 11c indicates a terminal (midpoint terminal) conducting with the midpoint of the series circuit of the switching elements 9a and 9b.

The inverter circuit 13a has a configuration in which three sets of series circuits of two switching elements are connected in parallel. Switching elements 9c and 9d, switching elements 9e and 9f, and switching elements 9g and 9h form a series circuit, respectively. Diodes are connected in anti-parallel to each switching element. The positive electrode side terminal (positive electrode terminal 11a) of the three sets of series circuits is connected to the output positive electrode end 19a of the voltage converter circuit 12, and the negative electrode side terminal (negative electrode terminal 11b) of the three sets of series circuits is the voltage converter circuit. It is connected to the output negative electrode end 19b of 12. Three-phase alternating current (U phase, V phase, W phase) is output from the midpoint terminal of the three sets of series circuits. Each of the three sets of series circuits corresponds to the power modules 8b, 8c, and 8d described later.

Since the configuration of the inverter circuit 13b is the same as that of the inverter circuit 13a, the specific circuit is not shown in FIG. Similar to the inverter circuit 13a, the inverter circuit 13b also has a configuration in which three sets of series circuits of two switching elements are connected in parallel. The terminal on the positive electrode side of the three sets of series circuits is connected to the output positive electrode end 19a of the voltage converter circuit 12, and the terminal on the negative electrode side of the three sets of series circuits is connected to the output negative electrode end 19b of the voltage converter circuit 12. There is. The hardware corresponding to each series circuit is referred to as a power module 8e, 8f, 8g.

A smoothing capacitor 6 is connected in parallel to the input ends of the inverter circuits 13a and 13b. In other words, the smoothing capacitor 6 is connected in parallel to the output end 19 of the voltage converter circuit 12. The smoothing capacitor 6 eliminates the pulsation of the current flowing between the voltage converter circuit 12 and the inverter circuits 13a and 13b.

The switching elements 9a-9h are transistors, typically IGBTs (Insulated Gate Bipolar Transistors), but may be other transistors, for example, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). Further, the switching element referred to here is used for power conversion, and is sometimes called a power semiconductor element. The same applies to the switching element included in the power module 8e-8g.

In FIG. 1, each of the broken lines 8a-8g corresponds to a power module. The power converter 2 includes seven sets of a series circuit of two switching elements. As hardware, two switching elements constituting a series circuit and a diode connected in antiparallel to each switching element are housed in one package (power module). In the following, when any one of the power modules 8a-8g is shown without distinction, it is referred to as a power module 8.

The positive electrode side terminal (positive electrode terminal 11a) of the seven power modules (7 sets of series circuits) is connected to the positive electrode of the smoothing capacitor 6, and the negative electrode side terminal (negative electrode terminal 11b) is connected to the negative electrode of the smoothing capacitor 6. Be connected.

Each midpoint terminal of the power module 8b-8d is connected to the motor 83a, and each midpoint terminal of the power module 8e-8g is connected to the motor 83b. The hardware structure of the power converter 2 will be described in detail below. The midpoint terminals of the six power modules 8b-8g are power cables 87 extending from the motors 83a and 83b via the output bus bar 23 described later. Connected to.

The power converter 2 includes a current sensor 44 that measures each of the three-phase alternating currents of the inverter circuit 13a, and a current sensor 44 that measures each of the three-phase alternating currents of the inverter circuit 13b. The power converter 2 is provided with a control circuit 3 that controls a switching element of the power module 8a-8g. The current sensor 44 is connected to the control circuit 3 by a signal line, and the control circuit 3 performs feedback control of the switching element based on the measured value of the current sensor 44. The power converter 2 includes a temperature sensor 17 that measures the temperature of the reactor 7, and a signal line that conveys the measurement data of the temperature sensor 17 is also connected to the control circuit 3. The control circuit 3 monitors the temperature of the temperature sensor 17 and adjusts the output of the voltage converter circuit 12 so that the reactor 7 does not overheat.

FIG. 2 shows a side view of the power converter 2. FIG. 3 shows a cross-sectional view of the power converter 2 in which the front side plate in FIG. 2 is cut. A connector hole 331 is provided on the front side plate in FIG. 2, and the position of the connector hole 331 is shown by a broken line in FIG. FIG. 4 shows a cross-sectional view of the power converter 2 cut along the IV-IV line of FIG. 3, and FIG. 5 shows a cross-sectional view of the power converter 2 cut along the V-V line of FIG.

The case 30 of the power converter 2 is divided into an upper cover 31, an upper case 32, and a lower case 33. The upper case 32 has upper and lower openings, the upper opening is closed by the upper cover 31, and the lower opening is closed by the lower case 33. The upper cover 31 is attached to the upper case 32 with a plurality of bolts 71. The lower case 33 is attached to the upper case 32 with a plurality of bolts 72. The lower case 33 is provided with a connector hole 331 to which a connector (not shown) of a power cable 87 (see FIG. 1) extending from the motors 83a and 83b is connected. Six connection terminals 23a connected to the connector of the power cable 87 face the connector hole 331. The connector hole 331 is provided on the side surface 336 of the lower case 33. Each of the six connection terminals 23a corresponds to the end of the output bus bar 23 (described later) connected to the midpoint terminal 11c of each of the six power modules 8b-8g.

As shown in FIG. 3, seven power modules 8a-8g are alternately laminated one by one with a plurality of coolers 28. In FIG. 3, only some power modules are coded, and the remaining power modules are omitted. Further, in FIG. 3, the reference numerals 28 are attached only to the two leftmost coolers, and the reference numerals are omitted for the remaining coolers. The laminate of the plurality of power modules 8 and the plurality of coolers 28 is housed and fixed in the upper case 32. The upper case 32 includes a middle plate 321. As shown in FIG. 3, the support wall 322 extends from the middle plate 321 and the laminate is sandwiched between the support wall 322 and the side plate 324 of the upper case 32. A spring 323 is sandwiched between the laminate and the support wall 322. The spring 323 pressurizes the laminated body in the laminated direction. By pressurizing, the power module 8 of the laminated body and the cooler 28 are brought into close contact with each other, and high cooling performance for the power module 8 is ensured. Hereinafter, the laminated body of the plurality of power modules 8 and the plurality of coolers 28 will be referred to as a power conversion unit 20.

The control board 29 is also fixed to the middle plate 321 of the upper case 32. The control board 29 is covered with the upper cover 31. By removing the upper cover 31, maintenance including replacement of the control board 29 becomes possible. A control terminal 11d extending from the power module 8 is connected to the control board 29. The control terminal 11d is a gate terminal conducting with the gate of the switching element housed in the power module 8, a sensor terminal conducting with a temperature sensor for measuring the temperature of the switching element, and the like. A control circuit 3 (see FIG. 1) for controlling the switching element housed in the power module 8 is mounted on the control board 29, and the control circuit 3 drives a drive signal to the switching element via the control terminal 11d. To send.

The capacitor element corresponding to the smoothing capacitor 6 in FIG. 1 is built in the capacitor module 60. The capacitor module 60 is also fixed to the upper case 32. As shown in FIG. 4, a support portion 326 extends from the inner wall of the upper case 32, and a tab 62 of the capacitor module 60 is fixed to the tip of the support portion 326 with a bolt 75. The capacitor module 60 and the positive electrode terminal 11a of the power module 8c included in the inverter circuit 13a are connected by a positive electrode bus bar 21, and the negative electrode terminal 11b is connected by a negative electrode bus bar 22. Although hidden in the figure, the positive electrode terminal 11a of the other power module 8 is also connected to the capacitor module 60 by the positive electrode bus bar 21. The negative electrode terminal 11b of the power module 8 is also connected to the capacitor module 60 by the negative electrode bus bar 22.

An output bus bar 23 is connected to the midpoint terminal 11c of the power module 8c. The output bus bar 23 is similarly connected to the other power modules 8b and 8d-8g midpoint terminals 11c included in the inverter circuit. The output bus bar 23 passes through the sensor unit 40. As described above, one end of the output bus bar 23 corresponds to the connection terminal 23a. Each of the connection terminals 23a is connected to each of the terminals on the connector side of the power cable 87 (see FIG. 1) connected to the connector hole 331. The sensor unit 40 is attached to a support portion 325 extending from the inner wall of the upper case 32 (see FIG. 3). Tabs 41 are provided at both ends of the sensor unit 40, and the tabs 41 are fixed to the support portion 325 (upper case 32) by bolts 74.

Inside the sensor unit 40, the current sensor 44 is arranged so as to be adjacent to the output bus bar 23. Six current sensors 44 are embedded in the sensor unit 40, and each current sensor 44 corresponds to each of the six output bus bars 23. The signal line 441 extending from the current sensor 44 passes through the inside of the sensor unit 40 and is connected to the control board 29. The six signal lines 441 corresponding to each of the six current sensors 44 extend in parallel toward the control board 29.

FIG. 5 is a cross-sectional view taken along the line VV of FIG. The reactor 7 is provided with a temperature sensor 17. The signal line 25 extending from the temperature sensor 17 extends to the surface of the sensor unit 40 facing the connector hole 331. A relay bus bar 24 is embedded in the sensor unit 40, and one end thereof is exposed on a surface facing the sensor unit and the connector hole 331 of the 40 so as to overlap the signal line 25. A signal line 442 is connected to the other end of the relay bus bar 24, and the signal line 442 is connected to the control board 29. As can be understood by superimposing FIGS. 4 and 5, the signal line 442 extends in parallel with the signal lines 441 of the plurality of current sensors 44 in a bundle.

The signal line 25 extending from the temperature sensor 17 and the relay bus bar 24 are fastened together with the sensor unit 40 by a bolt 73 at a position visible from the outside through the connector hole 331.

The power conversion unit 20, the capacitor module 60, the control board 29, and the sensor unit 40 including the plurality of power modules 8 are fixed to the upper case 32. On the other hand, the reactor 7 and the voltage converter 89 are fixed to the lower case 33. A temperature sensor 17 is connected to the reactor 7, and the signal line of the temperature sensor 17 is connected to the control board 29. However, the temperature sensor 17 (reactor 7) is fixed to the lower case 33, and the control board 29 is fixed to the upper case 32. Therefore, the temperature sensor 17 and the control board 29 cannot be connected until after the upper case 32 and the lower case 33 are connected. The signal line 442 connected to the control board 29 is connected to the relay bus bar 24 inside the sensor unit 40 fixed to the upper case 32, and the tip of the relay bus bar 24 is connected to the connector hole 331 of the sensor unit 40. It is exposed on the opposite surface. Then, the signal line 25 extending from the temperature sensor 17 is fastened together with the relay bus bar 24 by the bolt 73 and is conducting. As shown in FIG. 2, the bolt 73 that fastens the signal line 25 and the relay bus bar 24 together is visible from the outside of the case 30 through the connector hole 331. That is, the signal line 25 and the relay bus bar 24 can be connected through the connector hole 331 after connecting the upper case 32 and the lower case 33.

Further, the signal line 442 connected to the other end of the relay bus bar 24 together with the plurality of signal lines 441 extending from the plurality of current sensors 44 embedded in the sensor unit 40 are collectively connected to the control board 29. It is extended. By arranging the signal line 442 that transmits the signal of the temperature sensor 17 in parallel with the signal line 441 that transmits the signal of the current sensor 44, the wiring of the signal line 442 that transmits the signal of the temperature sensor 17 is simplified.

(Second Example) Next, the power converter 2a of the second embodiment will be described. FIG. 6 shows a circuit diagram of an electric vehicle 100a including the power converter 2a of the second embodiment. The power converter 2a is different from the power converter 2 of the first embodiment in that it includes two voltage converter circuits 12a and 12b. Other than that, it is the same as the power converter 2 of the first embodiment. The configuration of the electric vehicle 100a other than the power converter 2a is the same as that of the electric vehicle 100.

The first voltage converter circuit 12a is composed of a series circuit of two switching elements 9a and 9b, a reactor 7a, a filter capacitor 5, and a diode connected in antiparallel to each switching element. One end of the reactor 7a is connected to the input positive electrode end 18a, and the other end is connected to the midpoint of the series circuit. The filter capacitor 5 is connected between the input positive electrode end 18a and the input negative electrode end 18b. The input negative electrode end 18b is directly connected to the output negative electrode end 19b. The two switching elements 9a and 9b of the first voltage converter circuit 12a constitute a power module 8a, similarly to the voltage converter circuit 12 of the power converter 2 of the first embodiment.

The second voltage converter circuit 12b is composed of a series circuit of two switching elements 9a and 9b, a reactor 7b, a filter capacitor 5, and a diode connected in antiparallel to each switching element. One end of the reactor 7b is connected to the input positive electrode end 18a, and the other end is connected to the midpoint of the series circuit. The filter capacitor 5 is shared with the first voltage converter circuit 12a. The two switching elements 9a and 9b of the second voltage converter circuit 12b constitute the power module 8h.

The first voltage converter circuit 12a and the second voltage converter circuit 12b are connected in parallel. Further, the first voltage converter circuit 12a and the second voltage converter circuit 12b have the same circuit configuration. The control circuit 3 turns on / off the switching element 9a of the first voltage converter circuit 12a and the switching element 9a of the second voltage converter circuit 12b at the same timing. Further, the control circuit 3 turns on / off the switching element 9b of the first voltage converter circuit 12a and the switching element 9b of the second voltage converter circuit 12b at the same timing. The first voltage converter circuit 12a and the second voltage converter circuit 12b operate as if they were one voltage converter circuit. The power converter 2a can handle a large amount of electric power by including two voltage converter circuits 12a and 12b connected in parallel. Further, the power converter 2a includes a temperature sensor 17a for measuring the temperature of the reactor 7a and a temperature sensor 17b for measuring the temperature of the reactor 7b. The signal line that conveys the measurement data of the temperature sensors 17a and 17b is connected to the control circuit 3. The control circuit 3 monitors the temperature of the temperature sensors 17a and 17b, and adjusts the outputs of the two voltage converter circuits 12a and 12b so that the reactors 7a and 7b do not overheat.

FIG. 7 shows a cross-sectional view of the power converter 2a with the front side surface cut off. Two reactors 7a and 7b and a voltage converter 89 are fixed to the lower case 33. A power conversion unit 20a including a plurality of power modules 8, a capacitor module 60, a control board 29, and a sensor unit 40 are fixed to the upper case 32. The power conversion unit 20a includes eight power modules 8.

Although it is hidden behind the sensor unit 40 and cannot be seen in FIG. 3, temperature sensors 17a and 17b are attached to each of the two reactors 7a and 7b. The signal line 25a extending from the temperature sensor 17a and the relay bus bar 24a are fastened together with the sensor unit 40 by a bolt 73a at a position visible from the outside through the connector hole 331. The signal line 25b extending from the temperature sensor 17b and the relay bus bar 24b are jointly fastened to the sensor unit 40 with bolts 73b at a position visible from the outside through the connector hole 331. Similar to the relay bus bar 24 of the power converter 2 of the first embodiment, the relay bus bars 24a and 24b have one end connected to a signal line extending from the temperature sensor and the other end of the control board 29 through another signal line. It is connected to the.

As in the power converter 2a of the second embodiment, the technique disclosed herein may be applied to a power converter having a plurality of reactors. When a plurality of reactors are provided, at least one reactor is provided with a temperature sensor, and a first signal line extending from the temperature sensor and a second signal line conducting with the control board are provided from the connector hole in the sensor unit. It suffices if they are connected where they can be seen. Of course, all reactors are equipped with temperature sensors, even if the first signal line extending from each temperature sensor and the second signal line conducting with the control board are connected where they can be seen from the connector hole. good.

The points to be noted regarding the technique described in the examples will be described. The signal line 25 corresponds to an example of the first signal line, and the signal line 442 and the relay bus bar 24 correspond to an example of the second signal line.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples exemplified above. The technical elements described herein or in the drawings exhibit their technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the techniques exemplified in the present specification or the drawings can achieve a plurality of purposes at the same time, and achieving one of the purposes itself has technical usefulness.

2, 2a: Power converter 3: Control circuit 5: Filter capacitor 6: Smoothing capacitor 7, 7a, 7b: Reactor 8, 8a-8g: Power module 9a-9h: Switching element 11a: Positive terminal 11b: Negative terminal 11c: Midpoint terminal 11d: Control terminals 12, 12a, 12b: Voltage converter circuits 13a, 13b: Inverter circuit 17: Temperature sensor 20: Power conversion unit 21: Positive positive bus bar 22: Negative negative bus bar 23: Output bus bar 23a: Connection terminal 24: Relay Bus bar 25, 441, 442: Signal line 28: Cooler 29: Control board 30: Case 31: Upper cover 32: Upper case 33: Lower case 40: Sensor unit 41: Tab 44: Current sensor 60: Capacitor module 62: Tab 71 , 72, 73: Bolt 81: Battery 82: System main relay 87: Power cable 89: Voltage converter 100, 100a: Electric vehicle 331: Connector hole

Claims (1)

The case divided into the first case and the second case,
A reactor fixed to the first case and equipped with a temperature sensor,
A power conversion unit fixed to the second case and including a plurality of switching elements for power conversion, and a power conversion unit.
A sensor unit fixed to the second case and provided with a current sensor for measuring the current flowing through the output bus bar of the power conversion unit.
A control board fixed to the second case and connected to the current sensor and the power conversion unit by a signal line, respectively.
Equipped with
The first case is provided with a connector hole for connecting the output bus bar and an external cable.
A power converter in which a first signal line extending from the temperature sensor and a second signal line conducting with the control board are connected at a position visible from the connector hole in the sensor unit.

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