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
Toyota Motor Corporation**
Toyota-cho, Toyota, Aichi, 471-8572, Japan
Batery inverter IPM
A hybrid electric vehicle motor design requires high ef- motor
ﬁciency, high power/weight ratio and reliability. The per- iu
manent magnet synchronous motor (PM motor) is applied iv
in order to fulﬁll these requirements. The aim of this paper iw ωm
is to improve the increase of the torque produced by the Estimator
PM motor whose energy is supplied using batteries without vv
decreasing the eﬃciency of a motor and an inverter. vw Testimete
II. Controller Design ψ Calculator
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.
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,
in order to prevent the problem, it is decided that an or- 0.4
dinary current error feedback PI compensator is used to
control the torque at the low speed. This method is called 0 2000 4000
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.