Motorized Aircraft and Method for Determining Output and Number of Electric Motors in Motorized Aircraft

Patent metadata

Field	Value
Publication number	US-2017190435-A1
Application number	US-201515314848-A
Country	US
Kind code	A1
Filing date	Jun 30, 2015
Priority date	Jul 17, 2014
Publication date	Jul 6, 2017
Grant date	—

Abstract

A motorized aircraft is controlled by a drive control means ( 120 ) that rotationally drives a propulsion system propeller. The propulsion system propeller is driven by a plurality of electric motors ( 130 ). Total output of the plurality of electric motors ( 130 ) and required output satisfy the following relationship: Pmax(n−1)/n>Preq (where Pmax is the total output (kW) of the electric motors, n is the number of electric motors, and Preq is the required output (kW)).

First claim

1 . A motorized aircraft, comprising
a plurality of electric motors that rotationally drive a propulsion system propeller or fan, wherein total output of the plurality of electric motors and required output satisfy the following relationship:
P max( n− 1)/ n>P req

where Pmax is the total output (kW) of the electric motors, n is the number of electric motors, and Preq is the required output (kW).

2 . The electric aircraft according to claim 1 , wherein
the number of electric motors and the required output satisfy the following relationship:
√(0.15 P req)≦ n ≦√(0.15 P req)+2.

3 . The motorized aircraft according to claim 1 , further comprising:
a drive control means that controls each of the electric motors; an r.p.m. detection means that detects r.p.m. of the electric motor; an airflow detection means that detects atmospheric density and airspeed; and a current detection means that detects a current of the electric motor, wherein the drive control means has a characteristic data group regarding a torque characteristic of the propulsion system propeller or fan, which is recorded in advance, and includes a propeller torque estimation unit, a motor torque estimation unit, and a comparison detection unit, the propeller torque estimation unit estimates propeller torque of the propulsion system propeller or fan on the basis of revolutions per minute (r.p.m.) obtained from the r.p.m. detection means, data of the characteristic data group, and atmospheric density and airspeed obtained from the airflow detection means, the motor torque estimation unit estimates motor torque on the basis of a current obtained from the current detection means and r.p.m. obtained from the r.p.m. detection means, and the comparison detection unit compares estimated propeller torque and estimated motor torque with each other and detects an abnormal state of the electric motor on the basis of the fact that a difference between the propeller torque and a multiple of the motor torque is above a predetermined value.

4 . The motorized aircraft according to claim 3 , wherein
the comparison detection unit identifies an electric motor of the plurality of electric motors, in which the abnormal state occurs, on the basis of the fact that a difference between estimated propeller torque and a linear sum of estimated motor torque is above a predetermined value when the drive control means provides each of the electric motors with a motor torque-changing command.

5 . The motorized aircraft according to claim 3 , wherein
the comparison detection unit identifies an electric motor of the plurality of electric motors, in which the abnormal state occurs, on the basis of the fact that a difference between estimated propeller torque and a linear sum of estimated motor torque is above a predetermined value when the drive control means provides each of the electric motors with a motor torque-changing command for maintaining r.p.m. of the propulsion system propeller or fan.

6 . The motorized aircraft according to claim 3 , wherein
the drive control means makes, when causing the electric motors to generate power through rotations of the propulsion system propeller or fan, control such that a rate of motor torque of the plurality of electric motors differs from that during driving.

7 . The motorized aircraft according to claim 1 ,
wherein at least one of the plurality of electric motors rotationally drives the propulsion system propeller or fan via a one-way clutch.

8 . The motorized aircraft according to claim 3 , wherein
the drive control means includes an abnormal-case computation unit, and the abnormal-case computation unit calculates a torque difference between the estimated propeller torque and a linear sum of motor torque of the electric motors excluding the electric motor in which the abnormal state occurs, and estimates, on the basis of the calculated torque difference, torque of the electric motor in which the abnormal state occurs.

9 . The motorized aircraft according to claim 3 , wherein
the drive control means causes the comparison detection unit to operate at a plurality of different r.p.m. of the propulsion system propeller or fan to calculate an abnormality-case data group regarding a relationship between motor torque of an electric motor in which an abnormal state occurs and r.p.m. of the propulsion system propeller or fan.

10 . The motorized aircraft according to claim 9 , wherein
the drive control means makes control such that thrust or propeller torque before occurrence of an abnormal state is maintained within a predetermined range, on the basis of the characteristic data group and the abnormality-case data group.

11 . The motorized aircraft according to claim 3 , further comprising
a plurality of propellers or fans, wherein the drive control means makes control such that a difference between a value of a moment acting on the aircraft body after occurrence of an abnormal state of the electric motor and a value of a moment acting on the aircraft body before the occurrence is maintained within a predetermined range.

12 . A motorized aircraft, comprising:
at least a propulsion system propeller or fan; and a plurality of electric motors that rotationally drive the propulsion system propeller or fan.

13 . A method for determining output and the number of electric motors in a motorized aircraft including a plurality of electric motors that rotationally drive a propulsion system propeller or fan, the method comprising
determining the output and number of electric motors such that total output of the plurality of electric motors and required output satisfy the following relationship:
P max( n− 1)/ n>P req

where Pmax is the total output (kW) of the electric motors, n is the number of electric motors, and Preq is the required output (kW).

Assignees

• Japan Aerospace Exploration

Inventors

• Kobayashi Hiroshi
• Nishizawa Akira

Classifications

• B60L2220/42

  with use of more than one motor · CPC title

• H02P29/10

  for preventing overspeed or under speed · CPC title

• H02P5/46

  for speed regulation of two or more dynamo-electric motors in relation to one another · CPC title

• H02K7/116

  with gears · CPC title

• H02K16/00

  Machines with more than one rotor or stator {(machines for transmitting mechanical power from a driving shaft to a driven shaft and comprising structurally interrelated motor and generator parts H02K51/00; permanent magnet machines with multiple rotors or stators relatively rotated for vectorially combining the excitation fields or the armature voltages H02K21/029)} · CPC title