Toyota Camry Hybrid AHV40 Manual page 23

D Because an alternating current flows from this resolver to the excitation coil at a constant frequency, a
constant frequency is output to the coils S and C, regardless of the rotor speed. The rotor is oval, and the
distance of the gap between the stator and the rotor varies with the rotation of the rotor. Consequently,
the peak values of the waveforms output by the coils S and C vary in accordance with the position of the
rotor.
D The MG ECU constantly monitors these peak values, and connects them to form a virtual waveform. The
MG ECU calculates the absolute position of the rotor from the difference between the values of the coils
S and C. It determines the rotor direction based on the difference between the phases of the virtual
waveform of the coil S and the virtual waveform of the coil C. Furthermore, the MG ECU calculates the
rotational speed based on the amount of change in the rotor position within a given length of time.
D The diagrams below illustrate the waveforms that are output at coils A, S, and C when the rotor makes
a positive rotation of 180_ from a certain position.
(+)
Excitation
Coil A
(-)
(+)
Detection
Coil S
(-)
(+)
Detection
Coil C
(-)
0_
THS II (TOYOTA HYBRID SYSTEM II)
Virtual Waveform
Virtual Waveform
180_
TH-23
277TH105