JP2015186317A - Power conversion apparatus - Google Patents

Abstract

The present specification provides a technique for suppressing an influence caused by a decrease in current measurement accuracy while adopting a plurality of coreless current sensors in a power conversion device specialized in an electric vehicle including a main motor and a sub motor for traveling. . A power converter disclosed in this specification includes a first inverter circuit and a second inverter circuit. The first inverter circuit 22 supplies power to the main motor 7 that can drive the vehicle alone. The second inverter circuit 21 supplies power to the sub motor 6 having a maximum output smaller than that of the main motor 7. In addition, the power converter includes a first bus bar set 15 that transmits the output of the first inverter circuit 22 and a second bus bar set 14 that transmits the output of the second inverter circuit 21. A first current sensor 17 with a magnetic collecting core is attached to each bus bar of the first bus bar set 15, and a second current sensor 16 without a magnetic collecting core is attached to each bus bar of the second bus bar set 14. ing. [Selection] Figure 1

Description

  The present invention relates to a power conversion device that converts battery power into AC power and supplies it to a traveling motor.

  Power converters that convert battery power into AC power and supply it to a traveling motor often include a current sensor for feedback control of output current. The power conversion device is typically an inverter circuit that converts direct current into alternating current, but there is also an accompanying boost converter circuit that boosts the voltage of the battery and supplies the boosted voltage to the inverter circuit. Since the power converter of an electric vehicle handles a large current, a metal rod called a bus bar is used instead of a flexible wire to transmit a large current in the power converter. A current sensor is often provided in the bus bar. Three bus bars are prepared to supply power to the three-phase AC motor. Normally, three bus bars are arranged in parallel, and current sensors are attached to at least two bus bars.

  A typical current sensor includes a C-shaped magnetic block surrounding the bus bar and a magnetoelectric conversion element arranged in the C-shaped notch. The C-shaped magnetic block is called a magnetic collecting core because it collects magnetic flux. The magnetic flux generated around the bus bar is proportional to the flowing current. The conventional current sensor measures the magnetic flux collected by the magnetic collecting core with a magnetoelectric conversion element, and obtains the magnitude of the current flowing through the bus bar from the magnitude of the measured magnetic flux.

  In recent years, the accuracy of a magnetoelectric conversion element has been improved, and a current sensor using only a magnetoelectric conversion element without using a magnetic collecting core has been proposed. A current sensor without a magnetic collecting core is superior to a current sensor with a magnetic collecting core in terms of cost and installation space. However, if a current sensor without a magnetic collecting core is used for any one of the bus bars arranged in parallel, the magnetic field generated by another bus bar is added to the magnetoelectric conversion element as noise, so that the current measurement accuracy is sufficient. Is hard to say.

  Therefore, it has been proposed to use a current sensor with a magnetic collecting core and a current sensor without a magnetic collecting core in combination. In the following, for simplicity of explanation, a current sensor with a magnetic core is referred to as a cored current sensor, and a current sensor without a magnetic core is referred to as a coreless current sensor.

  Patent Document 1 proposes a technique of combining a cored current sensor and a coreless current sensor with respect to a power conversion device including two inverter circuits and one boost converter circuit. Each of the two inverters supplies power to each of two different motors. The boost converter circuit boosts the voltage of the battery and supplies it to each inverter circuit. The power conversion device of Patent Document 1 has two bus bar sets that supply power to each of the two motors, and a bus bar set that supplies battery power to the boost converter. In the case of a three-phase AC motor, one set of bus bar sets consists of three bus bars, and the bus bar set for the boost converter consists of two bus bars. In the power converter, a bus bar set for a boost converter is disposed between two bus bar sets for a motor. A current sensor with a core is used for the bus bar set for the motor, and a coreless current sensor is used for the bus bar for the boost converter (the bus bar on the high potential side). A coreless current sensor is used for the boost converter to reduce cost and occupied space, and a current sensor with a core is used for the bus bar set for the motor to ensure measurement accuracy.

  In Patent Document 2, three bus bars for supplying power to a three-phase AC motor are arranged in parallel, a cored current sensor is used for both bus bars, and a magnetic flux collecting coreless current sensor is used for the central bus bar. To do. Since the cored current sensor collects the magnetic flux generated by the bus bar to be measured, the magnetic flux leaking outside the core is reduced. The technique of Patent Document 2 reduces noise that the magnetic fluxes of the bus bars on both sides give to the coreless current sensor of the central bus bar.

JP 2013-013169 A JP2012-233741A

  The technology of Patent Document 1 can employ only one coreless current sensor. There is only one coreless current sensor that can be employed in the technology of Patent Document 2. Moreover, in the technique of Patent Document 2, three bus bars that supply current to one motor are measured by current sensors having different measurement accuracy. The high accuracy measurement result and the low accuracy measurement result are used in one control, and the control accuracy is lowered by the low accuracy measurement result.

  The present specification skillfully utilizes the electrical characteristics of an electric vehicle including at least two motors, and measures current while adopting a plurality of coreless current sensors in a power converter that supplies power to each of the two motors. Provide technology to reduce the impact of precision loss.

  The technology disclosed in this specification specializes in an electric vehicle having a main motor that can run the vehicle alone and a sub motor that is used together with the main motor and outputs an auxiliary driving force, and such an electric vehicle. A power conversion device using a plurality of coreless current sensors by skillfully utilizing the characteristics of the above is provided. The maximum output of the sub motor is smaller than the maximum output of the main motor.

  The electric vehicle includes a first inverter circuit that supplies electric power to the main motor and a second inverter circuit that supplies electric power to the sub motor. Since both the main motor and the sub motor are three-phase AC motors, each inverter circuit includes a set of three bus bars for transmitting output. The bus bar sets (first bus bar set) of the first inverter circuit are arranged in parallel to each other in one plane. The second bus bar set is arranged in parallel with the first bus bar set in the first plane. A current sensor with a core (first current sensor) is attached to each bus bar of the first bus bar set, and a coreless current sensor (second current sensor) is attached to each bus bar of the second bus bar set.

  Since the main motor may output driving force for traveling alone, drivability is affected if the control accuracy of the output current is low, that is, if the actual output torque deviates from the target value. On the other hand, since the sub motor outputs the driving force together with the main motor, the influence of the output fluctuation of the sub motor on the total driving force is small. Therefore, the control accuracy of the output current of the sub motor is not high, and even if the output torque deviates somewhat from the target value, the influence of the deviation on drivability is small. The power conversion device disclosed in this specification pays attention to the difference in the influence of the output control accuracy of the main motor and the sub motor on the drivability, and all of the bus bass sets for the sub motor that have a small influence on the drivability even with low accuracy. A coreless current sensor is used.

  The technology disclosed in this specification is a power that can suppress the influence of a decrease in current measurement accuracy on drivability while adopting a plurality of coreless current sensors specifically for an electric vehicle including a main motor and a sub motor for traveling. A conversion device is provided. Note that the power conversion device disclosed in this specification can be applied to any of an electric vehicle including a main motor and a sub motor but not including an engine, and a hybrid vehicle including an engine other than the main motor and the sub motor. Details and further improvements of the technology disclosed in this specification will be described in the following “DETAILED DESCRIPTION”.

It is a block diagram of the electric power system of the electric vehicle containing the power converter device of 1st Example. It is a skeleton figure of a power distribution mechanism. It is a typical perspective view of a current sensor with a core. It is a typical front view of the bus bar set of 1st Example. It is a typical top view of the bus bar set of 1st Example. It is a block diagram of the electric power system of the electric vehicle containing the power converter device of 2nd Example. It is a typical front view of the bus bar set of 2nd Example. It is a typical top view of the bus bar set of 2nd Example.

  (First Embodiment) A power converter according to a first embodiment will be described with reference to the drawings. The power conversion device of the embodiment is mounted on a hybrid vehicle. FIG. 1 shows a block diagram of the power system of the hybrid vehicle 2 including the power conversion device 5. The hybrid vehicle 2 includes an engine 8 and two three-phase AC motors (a sub motor 6 and a main motor 7) for traveling. The output of the engine 8 and the outputs of the two motors 6 and 7 are combined or distributed by the power distribution mechanism 40 and transmitted to the axle 9. The hybrid vehicle 2 generates power by rotating the sub motor 6 with the output of the engine 8 according to the situation. Electric power obtained by power generation is charged in the battery 3. Moreover, the hybrid vehicle 2 may generate electric power by the motors 6 and 7 using the kinetic energy of the vehicle during braking and charge the battery 3 in some cases. The power distribution mechanism 40 that connects the engine 8 and the two motors 6 and 7 will be described below.

  In FIG. 2, the skeleton figure of the gear structure of the power distribution mechanism 40 is shown. The power distribution mechanism 40 is mainly composed of two planetary gear sets (a first planetary gear set 50 and a second planetary gear set 60). The planetary gear set 50 is a gear set in which a sun gear 51, a carrier 52, and a ring gear 53 are combined. The carrier 52 is connected to the output shaft of the engine 8. The sun gear 51 is connected to the output shaft of the sub motor 6 (M1). An output gear 54 is coaxially fixed to the ring gear 53. The output gear 54 is engaged with the idle gear 55. The shaft of the idle gear 55 is connected to the axle 9. The output gear 64 of the second planetary gear set 60 is engaged with the idle gear 55, and the ring gear 63 of the second planetary gear set 60 is coaxially fixed to the output gear 64. The carrier 62 of the second planetary gear set 60 is fixed and does not rotate. The output shaft of the main motor 7 (M2) is coupled to the shaft of the sun gear 61 of the second planetary gear set 60.

  The torque output to the axle 9 is determined by the sum of the outputs of the engine 8, the sub motor 6, and the main motor 7 by the power distribution mechanism 40 having the above configuration. Depending on the situation, the axle 9 is driven by the outputs of the engine 8 and the main motor 7, and the sub motor 6 is rotated by a part of the driving force of the engine 8 to obtain electric power. Alternatively, the sub motor 6 may output driving force as an auxiliary, and the engine 8, the sub motor 6, and the main motor 7 may all output to obtain a large driving force. Further, the driving force may be output only by the engine 8. The above case is a drive mode called an HV mode using an engine and a motor (or only an engine). Further, when the engine 8 is stopped, the output of any of the sub motor 6 and the main motor 7 can be transmitted to the axle 9. A state in which the engine 8 is stopped and the vehicle travels with at least one of the driving force of the sub motor 6 and the main motor 7 is a driving mode called an EV mode. In other words, the HV mode is a traveling mode that uses the driving force of the engine, and the EV mode is a traveling mode that does not use the driving force of the engine.

  The hybrid vehicle 2 travels while switching between the EV mode and the HV mode depending on the vehicle speed, the accelerator opening, the remaining amount of the battery 3, and the inclination of the travel path. The maximum output of the main motor 7 is larger than the maximum output of the sub motor 6, and the main motor 7 is mainly used for traveling. In the EV mode, there are a case where the main motor 7 alone outputs a driving force for traveling, and a case where the main motor 7 and the sub motor 6 are used together to output a driving force for traveling. The sub motor 6 is mainly used as a starter motor that starts the engine 8 when switching from the EV mode to the HV mode, and as a generator. However, as described above, when a large driving force is required, the sub motor 6 also outputs a driving force as an auxiliary. On the other hand, the main motor 7 functions as a generator together with the sub motor 6 during braking. The electric power generated by the kinetic energy of the vehicle during braking is called regenerative electric power.

  Returning to FIG. 1, the electrical system of the hybrid vehicle 2 will be described. Electric power supplied to the two motors 6 and 7 is stored in the battery 3. The battery 3 is connected to the power conversion device 5 via the system main relay 4. The power conversion device 5 includes a voltage converter circuit 10, a sub inverter circuit 21, and a main inverter circuit 22. The voltage converter circuit 10 has a boost function that boosts the voltage of the battery 3 and supplies the boosted voltage to the inverter circuits 21 and 22, and a step-down function that lowers the voltage of the regenerative power to the voltage of the battery 3. The AC regenerative power generated by the motors 6 and 7 is converted to DC by the sub inverter circuit 21 or the main inverter circuit 22 and sent to the voltage converter circuit 10. The hybrid vehicle 2 also includes a power control unit 23 that controls the power conversion device 5. The power control unit 23 issues an output current command to the inverter circuits 21 and 22 of the power converter 5 based on an output current value measured by current sensors 16 and 17 described later, an accelerator opening, and the like. Based on this command, the inverter circuits 21 and 22 supply power to the motors 6 and 7. That is, the power control unit 23 controls the motors 6 and 7 by current feedback.

  The voltage converter circuit 10 includes a series circuit of two switching elements S7 and S8, and a reactor 13 having one end connected to an intermediate point of the series circuit and the other end connected to a high potential terminal on the battery side. The filter capacitor 12a is connected between the high potential terminal on the battery side and the ground terminal. In addition, a diode for passing a reverse current is connected in antiparallel to each of the switching elements S7 and S8. Step-up is performed by the operation of the switching element S8, and step-down is performed by the operation of the switching element S7. The voltage converter circuit 10 shown in FIG. 1 is also referred to as a chopper type buck-boost converter, and its mechanism is well known, and thus detailed description thereof is omitted.

  A sub inverter circuit 21 and a main inverter circuit 22 are connected in parallel to the high voltage output terminal of the voltage converter circuit 10. A smoothing capacitor 12b is connected between the high voltage output terminal of the voltage converter circuit 10 and the ground terminal. The smoothing capacitor 12b is inserted in order to suppress the pulsation of the current input to the inverter circuits 21 and 22.

  The sub inverter circuit 21 converts the boosted DC power into AC power and supplies it to the sub motor 6. The sub inverter circuit 21 has a configuration in which six switching elements S1 to S6 are connected as shown in FIG. A diode is connected in antiparallel to each switching element. The diode is called a freewheeling diode. As shown in FIG. 1, the sub motor 6 and the main motor 7 are both three-phase AC motors, and the circuit configuration of the sub-inverter circuit 21 that outputs three-phase AC is well known, so detailed description thereof is omitted.

  The main inverter circuit 22 converts the boosted DC power into AC power and supplies it to the main motor 7. The main inverter circuit 22 also has the same circuit configuration as the sub inverter circuit 21. However, the maximum output of the main inverter circuit 22 is larger than the maximum output of the sub inverter 21. In FIG. 1, the circuit configuration of the main inverter circuit 22 is not shown.

  The switching elements of the voltage converter circuit 10 and the inverter circuits 21 and 22 are typically transistors. More specifically, IGBTs are often employed as these switching elements.

  Since the power converter 5 handles a large current, the current path in the power converter 5 is not a flexible wire but a metal bar called a bus bar. The output line for transmitting the output from the inverter circuits 21 and 22 to the motors 6 and 7 is also constituted by a bus bar as hardware. This output line is composed of a set of three bus bars to supply power to the three-phase AC motor. The three current paths indicated by reference numeral 14 in FIG. 1 are output lines of the sub-inverter circuit 21 configured by combining three bus bars. Hereinafter, this output line is referred to as a sub bus bar set 14. Further, the three current paths indicated by reference numeral 15 in FIG. 1 are output lines of the main inverter circuit 22 configured by combining three bus bars. Hereinafter, this output line is referred to as a main bus bar set 15. A cable extending from the sub motor 6 is connected to one end of the sub bus bar set 14, and a cable extending from the main motor 7 is connected to one end of the main bus bar set 15.

  The sub bus bar set 14 is provided with a current sensor 16. One current sensor 16 is provided for each of the three bus bars of the sub-bus bar set 14. Similarly, the main bus bar set 15 is provided with a current sensor 17. One current sensor 17 is provided for each of the three bus bars of the main bus bar set 15. Here, the current sensor 16 is a coreless current sensor without a magnetism collecting core. On the other hand, the current sensor 17 is a cored current sensor with a magnetic collecting core. The difference between the cored current sensor and the coreless current sensor will be described next. Hereinafter, for convenience of explanation, the current sensor 16 is referred to as a “first coreless current sensor 16”, and the current sensor 17 is referred to as a “core-equipped current sensor 17”. That is, the sub bus bar set 14 that transmits power to the sub motor 6 is provided with a first coreless current sensor 16, and the member bus bar set 15 that transmits power to the main motor 7 is provided with a current sensor 17 with core. It has been.

  The difference between the cored current sensor and the coreless current sensor will be described. FIG. 3 is a schematic perspective view showing the cored current sensor 17. The cored current sensor 17 includes a C-shaped magnetic flux collecting core 17b that surrounds one bus bar 15a in the main bus bar set 15, and a magnetoelectric conversion element 17a disposed in a C-shaped notch of the magnetic flux collecting core 17b. Yes. The magnetic collecting core 17b is made of a magnetic material, and the magnetic flux generated by the current flowing through the bus bar 15a is collected in the magnetic collecting core 17b. The magnetic flux generated around the bus bar 15a is proportional to the current flowing through the bus bar. The magnetic flux collected by the magnetic collecting core 17b is measured by the magnetoelectric conversion element 17a, and the magnitude of the current flowing through the bus bar 15a can be obtained from the magnitude of the measured magnetic flux.

  On the other hand, the coreless current sensor has a structure in which the magnetic flux collecting core 17b of the cored current sensor 17 shown in FIG. 3 is removed. That is, the cored current sensor is composed only of a magnetoelectric conversion element. Since there is no magnetic collecting core, the coreless current sensor is superior to the current sensor with the magnetic collecting core in terms of cost and installation space. However, if a coreless current sensor is used for bus bars arranged in parallel, the magnetic field generated by the current flowing through the bus bar that is not the measurement target is added to the magnetoelectric conversion element as noise, so the current measurement accuracy of the coreless current sensor is not sufficient. hard.

  The configuration of the sub bus bar set 14 and the main bus bar set 15 provided in the power conversion device 5 of the first embodiment will be described with reference to FIGS. FIG. 4 is a front view of the bus bar sets 14 and 15 viewed from the bus bar extending direction (Y-axis direction). Note that each bus bar of the bus bar sets 14, 15 is drawn in cross section. FIG. 5 is a plan view of the bus bar sets 14 and 15 as viewed from a direction (Z-axis direction) orthogonal to both the extending direction and the alignment direction of the bus bars. It should be noted that FIG. 5 omits a later-described substrate 71 shown in FIG. As shown in FIG. 4, the cross-sectional shape of the three bus bars 14a of the sub bus bar set 14 is an elongated rectangular shape having the same shape. The bus bars 14a are arranged in parallel so that the wide side surfaces of the bus bars 14a face each other. And each bus bar 14a is located in a line so that the center of the section is located in one plane P parallel to the extending direction of the bus bar. Similarly, the cross-sectional shape of the three bus bars 15a of the main bus bar set 15 is also an elongated rectangle having the same shape as the bus bar 14a. The bus bars 15a are arranged in parallel along the direction in which the main bus bar sets 14 are arranged so that the wide side surfaces of the bus bars 15a face each other. And each bus bar 15a is located in a line so that the center of the cross section may be located in said plane P.

  Each of the three bus bars 14a of the sub-bus bar set 14 is provided with a first coreless current sensor 16. The first coreless current sensor 16 is disposed to face one side surface in the longitudinal direction (Z-axis direction) in the cross section of the bus bar 14a. As well represented in FIG. 4, all the first coreless current sensors 16 are arranged so as to face the side surfaces of the bus bar 14 a in the same direction. On the other hand, the three bus bars 15a of the main bus bar set 15 are provided with current sensors 17 with cores. The magnetoelectric conversion element 17a of the cored current sensor 17 is disposed so as to face one side surface in the longitudinal direction (Z-axis direction) in the cross section of the bus bar 15a, and the side surface is the first coreless current sensor 16 of the bus bar 14a. It is a side surface in the same direction as the arranged side. Further, as shown in FIG. 5, the magnetoelectric conversion elements 17 a of the first coreless current sensor 16 and the cored current sensor 17 are aligned in a straight line along the arrangement direction (X-axis direction) of the bus bar sets 14 and 15. .

  As shown in FIG. 4, the board | substrate 71 is provided in the direction (Z-axis direction) orthogonal to a row direction on the outer side of the bus bar sets 14 and 15. FIG. A plurality of signal lines extend from the substrate 71 toward the bus bar sets 14 and 15, and each signal line includes a magnetoelectric conversion element 17 a of the first coreless current sensor 16 and the cored current sensor 17 provided in the bus bar sets 14 and 15. Are connected one to one. Further, the board 71 is provided with a connector 72, and a cable from the power control unit 23 is connected to the connector 72 (not shown). Although not shown in the drawing, a circuit connecting the signal line and the connector 72 is configured on the substrate 71, and signals from the first coreless current sensor 16 and the cored current sensor 17 are the substrate 71 and the connector 72. To the power control unit 23.

  The effect by said structure is demonstrated. As described above, the maximum output of the main motor 7 is larger than the maximum output of the sub motor 6, and the hybrid vehicle 2 may travel by the main motor 7 alone. Here, in the current feedback control of the main motor 7, if the accuracy of the current sensor that measures the output current is low, the actual output current may deviate from the target current value. That is, the actual output torque of the main motor 7 may deviate from the target torque, which may affect the drivability of the hybrid vehicle 2. On the other hand, the sub motor 6 is mainly used as a starter motor and a generator, and is used to assist the driving force of the main motor 7 and the engine 8. The ratio of the output of the sub motor 6 to the main motor 7 is small. In the current feedback control of the sub motor 6, the accuracy of the current sensor that measures the output current is somewhat low, and even if the actual output torque of the sub motor 6 slightly deviates from the target value, the influence on the drivability of the hybrid vehicle 2 is small. According to the configuration of the first embodiment, the main bus bar set 15 that transmits the output to the main motor 7 is provided with the current sensor 17 with core, and the sub bus bar set 14 that transmits the output to the sub motor 6 has the coreless current. A sensor 16 is provided. That is, for measuring the output current of the main motor 7 that requires high measurement accuracy, a cored current sensor superior in measurement accuracy is used, and the output current of the sub motor 6 that does not require relatively high measurement accuracy is measured. For this, a coreless current sensor is used. As described above, by adopting the coreless current sensor for measuring the output current of the sub motor 6 having a small influence on the drivability, the cost reduction and the space saving of the power conversion device are realized while suppressing the influence on the drivability. be able to.

  Further, when the current sensors are provided in the bus bars arranged in parallel, the magnetic flux generated by the current flowing through the bus bar that is not the measurement target becomes a noise source of the current sensor provided in the bus bar that is the measurement target. According to said structure, the current sensor 17 with a core and the 1st coreless current sensor 16 are located in a line on the alignment direction (X-axis direction) of a bus bar. Here, since the magnetic flux generated in the range surrounded by the magnetic collecting core 17b of the cored current sensor 17 is collected in the magnetic collecting core 17b, the magnetic flux hardly leaks outside the magnetic collecting core 17b. Therefore, the magnetic flux generated from the main bus bar set 15 hardly passes through the first coreless current sensor 16. That is, the magnetic flux generated from the main bus bar set 15 is prevented from becoming a noise source of the first coreless current sensor 16.

  (Second Embodiment) A power conversion apparatus 30 according to a second embodiment will be described with reference to FIG. The power conversion device 30 is mounted on the hybrid vehicle 300. The hybrid vehicle 300 is a hybrid vehicle that can select two-wheel drive or four-wheel drive. FIG. 6 shows a block diagram of a power system of hybrid vehicle 300 including power conversion device 30. The hybrid vehicle 300 is obtained by adding a three-phase AC motor 32 for driving auxiliary drive wheels to the hybrid vehicle 2 of the first embodiment. The axle 9 connected to the power distribution mechanism 40 is connected to the front wheels, and the axle 35 connected to the motor 32 is connected to the rear wheels. That is, in the hybrid vehicle 300, the front wheels are driven by the engine 8, the main motor 7, and the sub motor 6, and the rear wheels are driven by the motor 32. Hereinafter, for convenience of explanation, the motor 32 is referred to as a “rear motor 32”. The hybrid vehicle 300 normally travels by two-wheel drive by the engine 8, the main motor 7, and the sub motor 6, but the rear motor 32 is driven by four-wheel drive as necessary. For example, the hybrid vehicle 300 temporarily drives the rear motor 32 when it is slippery on a snowy road, and travels by four-wheel drive. Alternatively, the hybrid vehicle 300 temporarily drives the rear motor 32 to assist torque when starting on a slope.

  As shown in FIG. 6, the power conversion device 30 includes a rear inverter circuit 31 for supplying three-phase AC power to the rear motor 32. The configuration of the power converter 30 is the same as that of the power converter 5 of the first embodiment except that the rear inverter circuit 31 is added. The power converter 30 includes the main inverter circuit 21, the sub inverter circuit 22, and the voltage converter circuit. 10 is provided. The rear motor 32 is an auxiliary drive source that is temporarily driven, and its maximum output is smaller than the maximum output of the main motor 7 that is the main drive source. As shown in FIG. 6, the input terminal of the rear inverter circuit 31 is connected to the battery-side input terminal of the power conversion device 30. That is, the power of the battery 3 is directly supplied to the rear inverter circuit 31. The rear motor 32 is driven by the voltage of the battery 3.

  The output line for transmitting the output from the rear inverter circuit 31 to the rear motor 32 is also composed of a bus bar, like the bus bar sets 14 and 15. The three current paths indicated by reference numeral 33 shown in FIG. 6 are output lines of the rear inverter circuit 31 configured by combining three bus bars. Hereinafter, this output line is referred to as a rear bus bar set 33. A cable extending from the rear motor 32 is connected to one end of the rear bus bar set 33. The rear bus bar set 33 is provided with a second coreless current sensor 34. Similar to the sub bus bar set 16, one second coreless current sensor 34 is provided for each of the three bus bars of the rear bus bar set 33. The output current value of the rear bus bar set 33 measured by the second coreless current sensor 34 is transmitted to the power control unit 37. Based on this output current value, the power control unit 37 performs current feedback control of the rear motor 32.

  The configuration of the rear bus bar set 33 will be described with reference to FIGS. FIG. 7 is a front view of the bus bar sets 14, 15, and 33 as viewed from the bus bar extending direction (Y-axis direction) as in FIG. 4. FIG. 8 is a plan view of the bus bar sets 14, 15, 33 viewed from the direction (Z-axis direction) orthogonal to both the bus bar extension direction and the bus bar arrangement direction of the bus bar sets 14, 15, 33 as in FIG. 5. FIG. As shown in FIG. 7, the cross-sectional shape of each bus bar 33a of the rear bus bar set 33 is an elongated rectangle similar to that of the bus bars 14a and 15a. The main bus bar set 14 and the sub bus bar set 15 are arranged in the same manner as in the first embodiment, and the rear bus bar set 33 is arranged in parallel to the main bus bar set 15 on the outer side in the arrangement direction of the main bus bar set 15. As shown in FIG. 7, the sub bus bar set 14 and the rear bus bar set 33 are arranged so as to sandwich the main bus bar set 33 therebetween. The centers of the cross sections of the bus bars 14a, 15a, 33a of the bus bar sets 14, 15, 33 are arranged so as to be located in one plane P parallel to the extending direction of the bus bar.

  Each of the three bus bars 33 a of the rear bus bar set 33 is provided with a second coreless current sensor 34. The second coreless current sensor 34 is arranged to face one side surface in the longitudinal direction (Z-axis direction) in the cross section of the bus bar 33a. As shown well in FIG. 7, the side surface is the side surface in the same direction as the side where the magnetoelectric transducer 17 a and the first coreless current sensor 16 of the cored current sensor 17 are arranged. Further, as shown in FIG. 8, the first coreless current sensor 16, the magnetoelectric transducer 17 a of the cored current sensor 17, and the second coreless current sensor 33 are arranged in the direction in which the bus bar sets 14, 15, 33 are arranged (X-axis direction). Along the straight line. The second coreless current sensor 33 is also connected to the substrate 73 as in the first embodiment.

  The effect by the structure of 2nd Example is demonstrated. As described above, the maximum output of the rear motor 32 is smaller than the maximum output of the main motor 7, and the rear motor 32 is a drive source that is temporarily driven for torque assistance. Therefore, in the current feedback control of the rear motor 32, the accuracy of the current sensor that measures the output current is somewhat low, and even if the actual output torque of the rear motor 32 slightly deviates from the target value, the influence on the drivability of the hybrid vehicle 300 is small. According to the configuration of the second embodiment, the cored current sensor 17 is provided for measuring the output current of the main motor 7, and the coreless current sensors 16, 34 are used for measuring the output current of the sub motor 6 and the rear motor 32. It is used. That is, in the measurement of the output current of the main motor 7 that requires high measurement accuracy, a cored current sensor that is superior in measurement accuracy is used, and the output current of the sub motor 6 and the rear motor 33 that does not require relatively high measurement accuracy. For the measurement, a coreless current sensor is used. In this way, by adopting a coreless current sensor for measuring the output current of the rear motor 32 that has little influence on drivability, the power conversion device of a hybrid vehicle that can select four-wheel drive can also be reduced in cost and space. Can be realized.

  Similarly to the first embodiment, the magnetic flux generated from the main bus bar set 15 in the range where the magnetic collecting core 17b is provided is generated along the magnetic collecting core 17b. As shown in FIG. 8, the cored current sensor 17 and the coreless current sensors 16, 34 are aligned on a straight line along the bus bar alignment direction (X-axis direction). Therefore, the magnetic flux generated from the main bus bar set 15 within a range in which the magnetic flux collecting core 17 b is provided hardly passes through the coreless current sensors 16 and 33. Therefore, the magnetic flux generated from the main bus bar set 15 is prevented from becoming a noise source of the coreless current sensors 16 and 33.

  “Main inverter circuit 22” is an example of “first inverter circuit”, and “sub inverter circuit 21” and “rear inverter circuit 31” are examples of “second inverter circuit”. Further, the “core current sensor 17” is an example of the “first current sensor”, and the “first coreless current sensor 16” and the “second coreless current sensor 34” are examples of the “second current sensor”. The “rear motor 32” in the second embodiment is an example of a “sub motor”.

  Hereinafter, points to be noted regarding the technology shown in the embodiments will be described. Although the second embodiment is a hybrid vehicle that normally drives the front wheels to perform two-wheel drive traveling and drives the rear wheels as necessary to perform four-wheel drive traveling, it is not limited to this configuration. For example, a power conversion device that employs the technology disclosed in the present specification is mounted on a hybrid vehicle that drives a rear wheel to drive a two-wheel drive, and drives a front wheel to drive a four-wheel drive if necessary. be able to.

  Specific examples of the present invention have been described in detail above, 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 this specification or the drawings exhibit 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 technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2, 300: Hybrid vehicle 3: Battery 4: System main relay 5, 30: Power converter 6: Sub motor 7: Main motor 9, 35: Axle 10: Voltage converter circuit 14: Sub bus bar set 15: Main bus bar set 16: First coreless current sensor 17: Current sensor with core 17a: Magnetoelectric transducer 17b: Magnetic collecting core 21: Sub inverter circuit 22: Main inverter circuit 23, 37: Power control unit 32: Rear motor 33: Rear bus bar set 34: Second Coreless current sensor

Claims (1)

A first inverter circuit for supplying power to a main motor capable of driving the vehicle alone;
A second inverter circuit having a smaller maximum output than the main motor and supplying electric power to a sub-motor that is used with the main motor and outputs an auxiliary driving force;
A first bus basset arranged parallel to each other in one plane and transmitting the output of the first inverter circuit;
A second bus bar set that is arranged in parallel with the first bus bar set in the plane and that transmits the output of the second inverter circuit;
A first current sensor with a magnetic collecting core attached to each bus bar of the first bus bar set;
A second current sensor without a magnetism collecting core attached to each bus bar of the second bus bar set;
A power conversion device for an electric vehicle, comprising:

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