# Development and Testing of the Torque Control for the

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```					Development and Testing of the Torque Control for
the Permanent-Magnet Synchronous Motor
Hideo NAKAI*, Hiroki OHTANI*, Eiji SATOH** and Yukio INAGUMA*
Toyota Central R&D Labs., Inc.*
Nagakute, Aichi, 480-1192, Japan
h-nakai@mosk.tytlabs.co.jp
Toyota Motor Corporation**
Toyota-cho, Toyota, Aichi, 471-8572, Japan

I. Introduction
Batery                      inverter                           IPM
A hybrid electric vehicle motor design requires high ef-                                                                                     motor
ﬁciency, high power/weight ratio and reliability. The per-                                                                             iu
V
manent magnet synchronous motor (PM motor) is applied                                                                                  iv
in order to fulﬁll these requirements. The aim of this paper                                                                           iw                 ωm
Torque
is to improve the increase of the torque produced by the                                                    Estimator
vu
PM motor whose energy is supplied using batteries without                                vv
decreasing the eﬃciency of a motor and an inverter.                                      vw                             Testimete

Voltage                 ψ
II. Controller Design                                                                       ψ Calculator
Calculator                                             Treferenc

The torque is increased in proportion to the increment
of the voltage V supplied to the inverter roughly speaking.
The voltage is, however, constant. Rectangular waveform                  Fig. 1. Block diagram of the Voltage Phase Compensator
voltages, which are described in eq.(1), are helpful to in-
crease the torque in the case that the voltage V is constant.
The method that controls the torque using the angle ψ of                                      III. Experimental Results
rectangular waveform voltages is called the voltage phase              Figure 2 shows the comparison of the voltage phase com-
compensator.                                                         pensator with the current feedback compensator for the
                                                                normalized torque Tn . The normalized torque is deﬁned
vu                  grw (ωt + ψ)                                dividing the average torque by the average torque of the
 vv  = v  grw (ωt + ψ − 2π )                         (1)
3                              current feedback compensator at 1000 [rpm]. This ﬁgure
vw               grw (ωt + ψ + 2π )
3                              shows that the voltage phase compensator improves the
1  if − π + 2iπ ≤ φ ≤          π
+ 2iπ         torque at more than 2800 [rpm]. Moreover, other experi-
grw (φ) =                  2                    2
−1 otherwise                                     ments conﬁrmed that the eﬃciency of a motor and an in-
(   i = 0, 1, 2, 3, ... )                 (2)   verter is not decrease.
1.2
The voltage phase compensator, however, has a prob-
Current Feedback Compensator
lem that the amplitude of the currents may be over above                     0.8                                               Voltage Phase Compensator

the current constrain at the low speed range. Therefore,
Tn

in order to prevent the problem, it is decided that an or-                   0.4

dinary current error feedback PI compensator is used to
0
control the torque at the low speed. This method is called                           0               2000               4000
ωm (rpm)
6000

the current feedback compensator. The proposed controller
consists of the above two compensators.
Fig. 2. The comparison of the voltage phase compensator with the
Figure 1 shows the block diagram of the voltage phase                  current feedback compensator for the torque
compensator. The outline of this method is as follows.
First, estimate the torque. Second, determine the angle ψ
using the error between the estimated torque and the ref-                                            IV. Conclusion
erenced torque. The control performance of the PM mo-
The problem to increase the torque without the decrease
tor, however, depends on the battery voltage, the angular            of the eﬃciency is studied. It has been conﬁrmed by simu-
velocity and etc. The compensator has a few blocks to                lation and experiment examinations that the proposed con-
compensate the variety to keep the control performance in            troller can improve the torque and the eﬃciency.
many control demands.

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