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Korea Aerospace Research Institute  Promising Technologies for Commercialization

Outline of Technology

TLO of the KARI

Person-in-charge

Senior Administrator Moon-Hee, Cho

E-mail : moonyxp@kari.re.kr
R&D Performance Diffusion Division 

Inventor

Senior Researcher Jung-yeop Lee

Team

Department of launch vehicle propulsion control

Status of right

• US : 9395703

Title

• MULTISTAGE CONTROL METHOD OF FLOW CON-

TROL VALVE USING DC MOTOR

Division of individual angular
speed limit areas depending
on stages of DC motor 

Precise flow rate control

Multistage 
control method of 

flow control valve 
using DC motor

 A technique for controlling a flow rate control valve 
by setting each limit value depending on stages 

according to angular speed components of a drive 

voltage that is applied during angular speed control 
over the DC motor and using a reference value of 
controlling target
 The DC motor is rotated at an intended angular speed 
so that a control valve to which the DC motor is 
mounted is controlled, thereby enabling precise control 
of a flow rate.

 Conceptual view of operation principle

Graph of flow rate control performance

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Lab-scale basic performance verification

Technical Readiness Level

TRL 1

TRL 2

TRL 5

TRL 6

TRL 7

TRL 8

TRL 9

TRL 4

Distinctiveness
•  The DC motor can be rotated at a desired angular speed, and therefore precise control of a flow 

rate is possible.

Technical effects

Technical features and advantages

Rapidly reaching a target value without overshoot or undershoot

Properly controlling a flow rate of a device whose thrust must be
changed to a low thrust level 

Additional tuning for controlling speed not necessary

Simple driving mechanism and freely changeable design using electrical

adjustment such as adjustment of a voltage

Setting an appropriate target value based on information about the
angular speed of the DC motor and by calculating the reduction ratio of gears

Speed control of DC motor

DC motor rotatable at a desired angular speed

■    Setting suitable limit values depending on stages according to 

angular speed components of a DC motor depending on a drive 
voltage that is applied during angular speed control over the DC 
motor, and executing speed control over the DC motor within 
a corresponding limit range -> A target value can be rapidly 
reached without overshoot or undershoot

■ DC motor rotatable at an intended angular speed, leading to pre-

cise flow rate control

Comparison of results of flow rate control by multistage control technique

TRL 3

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Technical detail

Dividing angular speed 

limit areas of a DC motor 
depending on stages based 
o n   a   p l u r a l i t y   o f   l i m i t 
values (SP1, SP2, SP3, SP4, 
...) according to a driving 
voltage that is applied to 

the DC motor

C o n t r o l l i n g   t h e   D C 
m o t o r   t o   r o t a t e   a t   a 
determined angular speed 
v a l u e   d e p e n d i n g   o n   a 
c o r r e s p o n d i n g   a n g u l a r 
speed instruction (Sn) to 

the DC motor within one 
angular speed limit area

When the angular speed value 

of the DC motor is outside the 
range of a limit value (SPn) of 
the angular speed limit area, the 

DC motor is controlled to rotate 
at a determined angular speed 
value within an angular speed 
limit area of a next stage.

Multistage control 
method of flow 
control valve 

using DC motor

•  For a proportional integral derivative (PID) controller which 

is widely used in the industry, while the result of dynamic 

characteristic is nonlinear during control, the result of the 

multistage control method is linear.

• In  the  multistage  control  method,  there  is  no  tuning 

procedure of trial and error which is a disadvantage of a PID 

controller.

• When controlling feedback, precise control is possible 

without overshoot or undershoot.

Controller for controlling a flow rate control valve

Flow rate control using multistage control method

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Market and future prospect

• The global control valve market will likely 

rise at a CAGR of 6.4% during the period 
between 2017 and 2025. At this rate, the 

market which was worth $6.01 billion in 2016 

will likely become worth $10.46 billion by 

2024. In terms of volume, the global control 

valves market is expected to reach 13,734.6 

thousand units in 2025.

Fields of precise flow rate control

Fields of motor control

Diversely applicable to the fields of aerospace, automobiles, watercraft, petrochemistry, 
development, construction, plant industry, etc. as an essential and core component

Robot, electric vehicle, etc.

•  Market characteristics of control valve technique

Reduction of production cost

Specialized items of

medium-sized company

Competition

Competition

Entire items of conglomerate

Reduction of experimental cost

Satisfaction of performance/

reliability requirements

Reduction of distribution/

service cost

Reduction of maintenance cost

Expansion of

 company

Targeting

 neighboring 

countries

Applications