Pulse-width-modulated controller, for vehicle electrically driven by direct current from storage battery and requiring highest possible efficiency in battery use, varies electrical power through silicon controlled rectifiers for permanent magnet dc motors. System is not restricted to dc motors

Sahinkaya, Y. E.

English

NASA Technical Reports Server

October 1970	 Brief 70-10435 
Optimal Electric-Drive System for Vehicles 
Rechargeable 
Battery 
dc-to-dc
Step-Down
Permanent-Magnet dc	 Load Motor Voltage 
Converter_j
Speed 
SteP 1
	
Throttle
	
Sensor 
dc-to-dc 
Voltage	 Mechanism 
Converter
Terrain-Slope 
Contioller	 Sensor 
Figure. 1. Essential Elements of the Electric-Drive System 
The problem: 
Design of a controller for a vehicle electrically 
driven by direct current from a storage battery and 
requiring the highest possible efficiency in use of its 
battery. 
The solution: 
A novel design (Fig. 1)is based on theoretical con-
cepts from modern control theory and on several 
justifiable assumptions; thus the uncertainties as-
sociated with earlier empirical approaches are elimin-
ated. A mathematical expression for the automatic 
control of the motor's armature voltage requires meas-
urement of the vehicle's speed and the slope of the 
terrain, and responds to an acceleration /deceleration 
controller. The controller uses a pulse-width-modula-
tion technique, according to an optimal control law, 
for variation of the electric power through silicon 
controlled rectifiers (SCR's) for the permanent-magnet 
dc motors. (continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19700000420 2020-03-17T00:50:35+00:00Z
---1 
1SCR1
2000
I	 D2 1 N754 
1N754
VT2 
1N4004
200 
SCR 
D3 
II ITC1
Battery 
Eb 
24V
I-
I 'a 
ra 
(E 
L
Ti Motor 
- -1 Equivalent	 I Ri 
I Armature	 I 50 1 
Circuit of the I JR2 I Motor  C2	 D4 100 i 
I 200 Q 1 N4004 SCR 4
	 1 N4004 SCR 3 
VT
200 
()t I * VTW3 
1N7541 I
SCR Step-up Voltage Converter 
—1 
	
R3100c	 I 
I Step-up D6 
	
Transformer	 I 
I y	 -iI'IJlC;--	 I. 
SCR Step-down Voltage Converter 
±T2	 - - i—.—.—i—. 
Figure 2. The SCR dc-to-dc Voltage Converters of the Minimum-Energy Controller 
Thus the motor's speed is so controlled, in accord-
ance with the sensed conditions, that minimum energy 
is expended during the motoring mode and maximum 
energy is recovered by regeneration during the coasting 
or (regenerative) braking mode. 
Two SCR converter subsystems (Fig. 2) are con-
trolled by the pulse-width modulator in conjunction 
with an armature-current direction sensor that deter-
mines which of the two converter systems is exclusively 
operative at any instant in accordance with the actual 
work load. One converter powers the motor for pro-
pulsion of the vehicle, and control is effected in the 
form of variable-duration pulses of battery voltage 
applied to the motor's armature. 
Pulses are produced by conduction of an SCR as 
triggered by the pulse-width modulator. Since these 
pulses are directly related to the instantaneous needs 
of the drive system, only sufficient power is supplied 
by the battery to meet such needs; battery energy is 
therefore conserved, and a minimum of energy is con-
verted to heat.
Potentially the system is widely applicable and is 
not necessarily restricted to dc motors. 
Notes: 
1. A prototype model of the optimal-drive system has 
been built and tested at the Jet Propulsion Labo-
ratory. 
2. Requests for further information may be directed 
to:
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: TSP70-10435 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546. 
Source: Y. E. Sahinkaya of

Caltech/JPL
under contract to

NASA Pasadena Office

(NPO-11210, 11227) 
Brief 70-10435	 Category 02 


Optimal electric-drive system for vehicles

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