JP7215395B2 - Electric drive system - Google Patents

Description

The present disclosure relates to electric drive systems.

In recent years, development of manned or unmanned aircraft called electric Vertical Take-Off and Landing aircraft (eVTOL) has been active as a type of aircraft different from airplanes having gas turbine engines. An electric vertical take-off and landing aircraft is equipped with multiple electric drive systems (EDS) that have motors and inverter devices, and multiple motors rotate multiple rotor blades to obtain lift and thrust. ing. An inverter device for an electric drive system may have an inverter circuit in which a plurality of switching elements connected in parallel are mounted. In the switching circuit disclosed in Patent Literature 1, the loss is reduced by changing the driving timing of the switching elements when the current is low.

Japanese Patent No. 6172175

Generally, in an electric vertical take-off and landing aircraft, operation modes such as landing mode and cruise mode are determined by a flight program. The inventors of the present application have found that there is room for further improvement in terms of loss reduction in electric drive systems that are driven according to operation modes. Therefore, there is a demand for a technique capable of reducing loss in an electric drive system that is driven according to the operation mode.

The present disclosure can be implemented as the following forms.

According to one aspect of the present disclosure, an electric drive system (10) is provided. This electric drive system has a motor (20), an inverter device (11) that controls the operation of the motor, and a control device (30) that controls the inverter device, wherein the inverter device comprises an inverter circuit (12) equipped with a plurality of switching elements (14) connected in parallel, and a circuit control section (15) capable of independently outputting a drive signal to each of the plurality of switching elements. ), wherein the circuit control unit (15) receives from the control device any one of a plurality of operation signals respectively indicating a plurality of operation modes with different required outputs; A simultaneously driven number, which is the number of switching elements to be simultaneously driven by synchronizing the timing of turning on the switching elements, is set to a driving number associated in advance with the received operation signal.

According to this form of the electric drive system, the circuit control unit receives from the control device one of a plurality of operation signals respectively indicating a plurality of operation modes with different required outputs, and operates the plurality of switching elements. The number of simultaneously driven switching elements, which is the number of switching elements to be simultaneously driven by synchronizing the ON timing, is set to the number of drives previously associated with the received operation signal. By previously associating a small value for , the number of simultaneous drives can be reduced when the actual operation mode is an operation mode with a small required output. Therefore, loss can be reduced in an electric drive system that is driven according to the operation mode.

The present disclosure may also be embodied in various forms. For example, it can be implemented in the form of a control method for an electric drive system, an electric vehicle including an electric drive system, or the like.

1 is a schematic diagram showing a schematic configuration of an electric vertical take-off and landing aircraft equipped with an electric drive system; FIG. 1 is a block diagram showing a schematic configuration of an electric vertical take-off and landing aircraft; FIG. FIG. 3 is an explanatory diagram for explaining the configuration of a switching circuit; FIG. 4 is an explanatory diagram showing an example of a gate signal in takeoff mode; FIG. 4 is an explanatory diagram showing an example of a gate signal in cruise mode; FIG. 11 is an explanatory diagram showing an example of a gate signal in takeoff mode of the second embodiment; FIG. 4 is an explanatory diagram showing an example of a gate signal in a takeoff mode when one switching element fails; FIG. 5 is an explanatory diagram showing an example of a gate signal in cruise mode when one switching element fails;

A. First embodiment:
An electric drive system 10 (hereinafter also referred to as "EDS (Electric Drive System) 10") as an embodiment of the present disclosure shown in FIG. It is installed on the Landing aircraft (also called 500). The eVTOL 500 is configured as a manned aircraft that is electrically driven and capable of vertical takeoff and landing. The eVTOL 500 includes an airframe 510, an integrated ECU 520, and multiple EDSs 10. Although the eVTOL 500 of the present embodiment is equipped with four EDSs 10, the number of EDSs 10 is not limited to four, and an arbitrary plurality of EDSs 10 such as eight may be installed. Redundancy is ensured in the eVTOL 500 by installing a plurality of EDSs 10 .

Airframe 510 includes a fuselage portion of eVTOL 500, main wings, and a tail wing. A passenger compartment is formed inside the fuselage 510 .

The integrated ECU 520 is configured by a computer having a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). This CPU functions as a flight controller that controls the overall operation of the eVTOL 500 by executing a control program pre-stored in the ROM. Overall operations of the eVTOL 500 include, for example, takeoff operations, cruise operations, landing operations, and the like. These operations are executed with each operation mode set based on the set flight program, but may be executed with the operation mode set by the crew member's control. The integrated ECU 520 outputs a control command to each control device 30 of each EDS 10, which will be described later. The integrated ECU 520 also outputs an operation signal indicating the operation mode of the eVTOL 500 to the control device 30 of each EDS 10 . Each EDS 10 receives an operation signal from the integrated ECU 520 and controls the output according to the operation signal.

Operation modes of the eVTOL 500 include, for example, a takeoff mode, a cruise mode, a landing mode, and an emergency mode. The takeoff mode is an operation mode selected when the eVTOL 500 takes off, and is an operation mode with the highest required output among the plurality of operation modes. The cruise mode is an operation mode that is selected when the eVTOL 500 is cruising after takeoff, and is an operation mode that requires the lowest required output among a plurality of operation modes. The landing mode is an operation mode selected when the eVTOL 500 lands after cruising, and is an operation mode that requires a higher power output than the cruising mode. The emergency mode is an operation mode that is selected in an emergency when an abnormality such as a failure occurs in one of the plurality of EDSs 10. In order to compensate for the output of the EDS 10 in which an abnormality has occurred, a request for each EDS 10 is made. It is an operating mode that requires increased output. The required output in each operating mode is different from each other.

The four EDSs 10 shown in FIG. 2 are configured as driving devices for rotationally driving rotor blades (not shown). Each EDS 10 has a control device 30, a motor 20, and an inverter device 11, respectively. Each EDS 10 is electrically connected to a power supply device (not shown) via high voltage wiring. A plurality of power supply devices may be mounted on the eVTOL 500, and each EDS 10 may be connected to a different power supply device. In this embodiment, the power supply device is composed of a high voltage generator. The power supply device is not limited to a high-voltage generator, and may be configured by an arbitrary power supply source such as a secondary battery such as a lithium ion battery or a fuel cell.

The control device 30 is composed of a microcomputer having a CPU and a storage device. Such a CPU controls the operation of the EDS 10 by executing a control program pre-stored in the storage device. Control device 30 receives from integrated ECU 520 any one of a plurality of operation signals respectively indicating a plurality of operation modes of eVTOL 500, and transmits the received operation signal to control unit 16 of circuit control unit 15, which will be described later. Output.

The motor 20 rotationally drives the rotor via a shaft (not shown). In this embodiment, the motor 20 is composed of a 4-pole, 3-phase, 6-coil brushless motor, and outputs rotational motion according to voltage and current supplied from an inverter circuit 12, which will be described later. Note that the motor 20 is not limited to a brushless motor, and may be an arbitrary motor such as an induction motor or a reluctance motor. Further, the rotation of the motor 20 may be decelerated and transmitted to the rotor blades by connecting the motor 20 and the rotor blades together with the shaft through gears (not shown).

Inverter device 11 controls the operation of motor 20 . The inverter device 11 has an inverter circuit 12 and a circuit control section 15 .

The inverter circuit 12 converts the DC voltage supplied from the power supply device into a three-phase AC voltage and supplies it to the motor 20 . The inverter circuit 12 has a total of three legs provided for each of U-phase, V-phase, and W-phase. Each leg has two upper and lower switching circuits 13 . That is, the inverter circuit 12 has a total of six switching circuits 13 .

As shown in FIG. 3, the switching circuit 13 includes a plurality of switching elements 14 connected in parallel. A free wheel diode (not shown) is connected to each switching element 14 . In this embodiment, the switching element 14 is composed of an IGBT (Insulated Gate Bipolar Transistor), but is not limited to an IGBT, and is composed of a power element such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). . In this embodiment, the number of switching elements 14 connected in parallel with each other in each switching circuit 13 is four, but the number is not limited to four, and may be any number such as two or six. good.

The circuit control section 15 controls the switching circuit 13 . The circuit control unit 15 is configured to be able to output a gate signal GS as a drive signal to each switching element 14 independently. 3 and subsequent drawings, the gate signals GS input to the switching elements 14 are also indicated as a first gate signal GS1, a second gate signal GS2, a third gate signal GS3, and a fourth gate signal GS4. there is The circuit control section 15 has a control section 16 and a drive section 17 .

The control unit 16 is composed of a microcomputer having a CPU and a storage device. Control unit 16 receives a torque command from control device 30 shown in FIG. It supplies the signal GS. More specifically, the circuit control unit 15 performs PWM (Pulse Width Modulation) control on the gate signal GS supplied to the gate electrode of each switching element 14 at a duty ratio corresponding to the operation mode. The gate signal GS is generated by comparing a reference triangular wave having a carrier frequency with a desired modulated wave. Control unit 16 calculates the energization time of each switching element 14 shown in FIG. 3 based on the torque command received from control device 30 shown in FIG. 2 and outputs a PWM signal to drive unit 17 .

Control unit 16 also receives one of a plurality of operation signals respectively indicating a plurality of operation modes of eVTOL 500 from control device 30 shown in FIG. is set to the drive number pre-associated with the received motion signal. “The number of simultaneously driven switching elements 14 ” means the number of switching elements 14 that are simultaneously driven by synchronizing the timing of turning on the plurality of switching elements 14 .

In this embodiment, the control unit 16 sets the number of simultaneously driven switching elements 14 to four when the operation mode of the eVTOL 500 is the takeoff mode. In other words, when the required output of the eVTOL 500 is maximum, the control unit 16 sets the number of simultaneously driven switching elements 14 equal to the number of drivable switching elements 14 . "The number of drivable switching elements 14" means the number of switching elements 14 in which an abnormality such as a failure has not occurred. Therefore, when all switching elements 14 are in a normal state, the number of drivable switching elements 14 is the same as the number of switching elements 14 mounted.

Further, the control unit 16 sets the number of simultaneously driven switching elements 14 to 1 when the operation mode of the eVTOL 500 is the cruise mode. Further, the control unit 16 sets the number of simultaneously driven switching elements 14 to 3 when the operation mode of the eVTOL 500 is the landing mode, and simultaneously drives the switching elements 14 when the operation mode of the eVTOL 500 is the emergency mode. Set the number to 2.

The drive section 17 is configured by a buffer circuit for driving the switching element 14 . The driving section 17 outputs a gate signal GS to each switching element 14 according to the PWM signal received from the control section 16 . Further, the drive unit 17 monitors the state of each switching element 14 .

FIG. 4 shows an example of the gate signal GS in the takeoff mode in which the required output is maximum. Each switching element 14 is controlled so that the timing to be turned on is synchronized in all operation modes. Note that in FIG. 4 and subsequent drawings, the horizontal axis indicates time (t). In the present embodiment, the number of simultaneously driven switching elements 14 in the takeoff mode is set to 4, so the circuit control unit 15 always determines all the switching elements 14 to be simultaneously driven in the takeoff mode. Therefore, the waveform of the gate signal GS input to each switching element 14 is the same.

FIG. 5 shows an example of the gate signal GS in the cruise mode with the minimum required output. In this embodiment, since the number of simultaneously driven switching elements 14 in the cruise mode is set to 1, the circuit control unit 15 controls the first gate signal GS1, the second gate signal GS2, the third gate signal GS3 and the fourth gate signal GS3. The gate signal GS4 is set to turn on alternately one by one in this order. At the timing when the first gate signal GS1 is on, the other three gate signals GS2-4 are off. Similarly, at the timing when the second gate signal GS2 is on, the other three gate signals GS1, 3, and 4 are off, and at the timing when the third gate signal GS3 is on, the other three gate signals The gate signals GS1, 2 and 4 are off, and the other three gate signals GS1 to GS3 are off at the timing when the fourth gate signal GS4 is on. The order in which each gate signal GS is turned on is not limited to the order shown in FIG. 5, and may be set arbitrarily.

In this manner, the circuit control unit 15 determines the switching elements 14 to be simultaneously driven among the plurality of switching elements 14 according to the set number of simultaneously driven elements. In the example shown in FIG. 5, the circuit control unit 15 changes one of the switching elements 14 to be simultaneously driven every predetermined period.

According to the EDS 10 of the present embodiment described above, the circuit control unit 15 sets the simultaneous driving number, which is the number of the switching elements 14 to be simultaneously driven by synchronizing the timing of turning on the plurality of switching elements 14, to the operating mode of the eVTOL 500. is set to the number of drives preliminarily associated with the operation signal indicating . Therefore, by previously associating a small value as the number of simultaneous driving with an operation mode with a small required output, the number of simultaneous operations can be set small when the actual operation mode is an operation mode with a small required output. can be done. Therefore, loss can be reduced in the EDS 10 driven according to the operation mode.

In general, the eVTOL 500 is driven in the cruise mode, which requires less power, for a longer period of time than in the takeoff and landing modes, which require more power. According to the EDS 10 of this embodiment, the number of simultaneous drives in the cruise mode can be set to a small number, so the loss can be reduced over a long period of time, and the cruising distance of the eVTOL 500 can be extended.

Also, in general, in the eVTOL 500, the required output in an operation mode such as a cruise mode in which the required output is small is much smaller than the required output in an operation mode in which the required output is large such as a takeoff mode. For example, the required power for cruise mode is about one quarter of the required power for takeoff mode. Since the EDS 10 of the present embodiment is mounted on the eVTOL 500, it is possible to increase the loss reduction effect and effectively extend the cruising distance of the eVTOL 500 compared to a configuration mounted on an automobile or the like.

In addition, since the EDS 10 of the present embodiment is mounted on the eVTOL 500, the switching of the operation mode is less than that of a configuration mounted on an automobile or the like, and the frequency of changing the number of simultaneously driven switching elements 14 becomes excessively high. can be suppressed. Therefore, it is possible to suppress an increase in the failure rate of the circuit control unit 15 and the switching circuit 13 due to the change in the number of simultaneous drives.

Further, when the operation signal received from the control device 30 indicates the takeoff mode, the circuit control unit 15 sets the number of simultaneously driven switching elements 14 equal to the number of drivable switching elements 14. do. In other words, in a situation where the eVTOL 500 is driven in the operation mode with the highest required output, the number of simultaneously driven switching elements 14 is set to the maximum value. Therefore, in a situation where the eVTOL 500 is driven in the operation mode with the highest required output, the configuration of the switching circuit 13 is smaller than the configuration in which the number of simultaneously driven switching elements 14 is set to be smaller than the number of drivable switching elements 14. can be simplified, and an increase in cost required for manufacturing the switching circuit 13 can be suppressed. In addition, in an operation mode with a large required output, it is possible to prevent the number of simultaneously driven switching elements 14 from being set excessively low and the required output not being satisfied.

In addition, the circuit control unit 15 determines the switching elements 14 to be simultaneously driven among the plurality of switching elements 14 according to the set number of simultaneous driving, and selects a part of the switching elements 14 to be simultaneously driven in advance. Change every set period. Therefore, the heat generated by the switching operation can be equalized in the plurality of switching elements 14, and a decrease in heat dissipation efficiency can be suppressed.

B. Second embodiment:
The EDS 10 of the second embodiment differs from the EDS 10 of the first embodiment in setting the number of simultaneously driven switching elements 14 . Since other configurations are the same as those of the EDS 10 of the first embodiment, the same configurations are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the EDS 10 of the second embodiment, the circuit control unit 15 sets the number of simultaneously driven switching elements 14 to be one less than the number of mounted switching elements 14 when the required output of the eVTOL 500 is maximum. With such a configuration, in the EDS 10 of the second embodiment, even when an abnormality such as a failure occurs in any one of the plurality of switching elements 14, the operation mode of the eVTOL 500 is changed. The simultaneous drive number associated with the indicated operating signal can be satisfied.

FIG. 6 shows an example of the gate signal GS in the takeoff mode in which the required output is maximum. In this embodiment, the circuit control unit 15 sets the number of simultaneously driven switching elements 14 in the takeoff mode to three. The circuit control unit 15 sets the fourth gate signal GS4, the third gate signal GS3, the second gate signal GS2, and the first gate signal GS1 alternately one by one in this order. The order in which each gate signal GS is turned off is not limited to the order shown in FIG. 6, and may be set arbitrarily. The gate signal GS in the cruise mode with the minimum required output is the same as in FIG.

FIG. 7 shows an example of the take-off mode gate signal GS when an abnormality occurs in the switching element 14 to which the fourth gate signal GS4 is input. Since one of the four switching elements 14 is abnormal, the circuit control unit 15 always determines the other three switching elements 14 to be simultaneously driven in the takeoff mode. As a result, the switching element 14 that has been in the OFF state at a certain timing when none of the plurality of switching elements 14 has an abnormality is in the ON state at that timing instead of the switching element 14 in which the abnormality has occurred. It is said that Therefore, the waveforms of the gate signals GS1 to GS3 input to the three switching elements 14 in which no abnormality has occurred are all the same. In this way, when an abnormality occurs in one of the plurality of switching elements 14, the circuit control unit 15 causes the switching elements 14 other than the switching element 14 to be simultaneously driven to be switched to an abnormal condition. are simultaneously driven in place of the switching element 14 in which .

FIG. 8 shows an example of the gate signal GS in the cruising mode when an abnormality occurs in the switching element 14 to which the fourth gate signal GS4 is input. Since one of the four switching elements 14 has an abnormality, the circuit control unit 15 selects the switching element 14 to be simultaneously driven from among the other three switching elements 14 . In other words, the switching element 14 to which the fourth gate signal GS4 is input is always excluded from being simultaneously driven. In the present embodiment, since the number of simultaneously driven switching elements 14 in the cruise mode is set to 1, the circuit control section 15 outputs the first gate signal GS1, the second gate signal GS2 and the third gate signal GS3 to this It is set to be turned on one by one alternately in order.

The EDS 10 of the second embodiment described above has the same effects as the EDS 10 of the first embodiment. In addition, the circuit control unit 15 sets the number of simultaneous driving of the switching elements 14 in the operation mode in which the required output of the eVTOL 500 is the maximum to a number smaller than the number of the switching elements 14 mounted. Therefore, even when an abnormality occurs in one of the plurality of switching elements 14 connected in parallel, the required output can be satisfied. Therefore, the redundancy of the EDS 10 can be ensured, and a decrease in safety can be suppressed. Further, when an abnormality occurs in any one of the plurality of switching elements 14, among the plurality of switching elements 14, the switching elements 14 other than the switching element 14 to be driven simultaneously are replaced with the switching element 14 in which the abnormality has occurred. are driven at the same time, it is possible to suppress a decrease in safety.

C. Other embodiments:
C-1. Alternative Embodiment 1:
The number of simultaneously driven switching elements 14 and the waveform of the gate signal GS input to each switching element 14 shown in each of the above-described embodiments are merely examples, and can be changed in various ways. For example, the circuit control unit 15 omits determining the switching elements 14 to be simultaneously driven according to the set number of simultaneous drives, and randomly selects the switching elements 14 so as to satisfy the set number of simultaneous drives. may be driven. Further, for example, the circuit control unit 15 may change all the switching elements 14 to be simultaneously driven every predetermined period, or may change the switching elements 14 to be simultaneously driven every predetermined period. do not need to be changed to Further, for example, the circuit control unit 15 may preferentially determine the switching elements 14 that are not adjacent to each other among the plurality of switching elements 14 as the switching elements 14 to be simultaneously driven. According to this aspect, it is possible to further suppress the deterioration of the heat dissipation efficiency of the switching element 14 . Further, for example, in the first embodiment, the circuit control unit 15 is not limited to the operation signal indicating the takeoff mode, and the operation signal indicating any one of the takeoff mode, the landing mode, and the emergency mode. , the number of simultaneously driven switching elements 14 may be set equal to the number of drivable switching elements 14 . Further, for example, in the second embodiment, the circuit control unit 15 may set the number of simultaneously driven elements in the operation mode with the maximum required output to be less than the number of mounted switching elements 14 by two or more. Even with such a configuration, the same effects as those of the above-described embodiments can be obtained.

C-2. Alternative Embodiment 2:
Although the EDS 10 in each of the above embodiments is mounted on the eVTOL 500, it may be mounted on any electric moving object such as any electric aircraft or watercraft without being limited to the eVTOL 500.

The present disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from the scope of the present disclosure. For example, the technical features in each embodiment corresponding to the technical features in the form described in the outline of the invention are used to solve some or all of the above problems, or Substitutions and combinations may be made as appropriate to achieve part or all. Also, if the technical features are not described as essential in this specification, they can be deleted as appropriate.

The controllers, external devices, and techniques described in this disclosure are dedicated computers provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. It may be realized by Alternatively, the controls and techniques described in this disclosure may be implemented by a dedicated computer provided by configuring the processor with one or more dedicated hardware logic circuits. Alternatively, the controllers, external devices, and techniques described in this disclosure may be processors and memory configured with one or more hardware logic circuits programmed to perform one or more functions. may be implemented by one or more dedicated computers configured by a combination of The computer program may also be stored as computer-executable instructions on a computer-readable non-transitional tangible recording medium.

DESCRIPTION OF SYMBOLS 10... Electric drive system (EDS), 11... Inverter apparatus, 12... Inverter circuit, 13... Switching circuit, 14... Switching element, 15... Circuit control part, 20... Motor, 30... Control apparatus, GS... Gate signal (drive signal)

Claims (6)

An electric drive system (10) comprising a motor (20), an inverter device (11) controlling the operation of the motor, and a control device (30) controlling the inverter device,
The inverter device includes an inverter circuit (12) equipped with a plurality of switching elements (14) connected in parallel, and a circuit control capable of outputting drive signals independently to each of the plurality of switching elements. a portion (15),
The circuit control unit (15)
receiving from the control device any one of a plurality of operation signals respectively indicating a plurality of operation modes with different required outputs;
setting a simultaneously driven number, which is the number of switching elements to be simultaneously driven by synchronizing the timing of turning on the plurality of switching elements, to a driving number associated in advance with the received operation signal;
electric drive system. The electric drive system according to claim 1,
When an abnormality occurs in any one of the simultaneously driven switching elements, the circuit control unit controls switching elements other than the simultaneously driven switching elements among the plurality of switching elements in the switching element in which the abnormality has occurred. Simultaneously drive instead of the element,
electric drive system. In the electric drive system according to claim 1 or claim 2,
Used by being mounted on an electric vertical takeoff and landing aircraft (500),
When the received operation signal is the operation signal indicating any one of a takeoff mode, a landing mode, and an emergency mode of the electric vertical take-off and landing aircraft, the circuit control unit , setting the simultaneously driven number to be the same as the number of drivable switching elements;
electric drive system. In the electric drive system according to claim 1 or claim 2,
The circuit control unit sets the number of simultaneous drives in the operation mode in which the required output is the maximum to a number smaller than the number of the plurality of switching elements mounted.
electric drive system. In the electric drive system according to any one of claims 1 to 4,
The circuit control unit determines a switching element to be simultaneously driven among the plurality of switching elements according to the set number of simultaneous drives.
electric drive system. In the electric drive system according to claim 5,
The circuit control unit changes at least one of the switching elements to be simultaneously driven every predetermined period.
electric drive system.

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