Sharp AE-XM24HR, Service Manual

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AEXM24HR
2 – 8
microcomputer works in an internal processing so that detection is enabled only when it is ON. Based on the position signal detected, actual PWM
waveform output timing is determined. Since it does not use a filter circuit, the accuracy of detection.
The microcomputer works in an internal processing to eliminate spiky voltage during the regenerative process.
Furthermore, even if the induced voltage is low, position detection is still possible, and it allows sensor-less operation at low rotation speed in the ini-
tial stage of operation. These reduce the starting current and improve reliability of IPM.
2.6.2 180
°
energizing control
This is the control system to moderate the speed by the current phase difference for higher efficiency and lower noise of the compressor. The current
phase difference control is the control system paid attention to the interrelation between efficiency and phase gap generated by the applied voltage of
motor and current in the coil of motor as shown in the figure below.
This control is the forced magnetization system independent of the location of rotor, detecting the phase difference between driving voltage phase and
line current phase flowing in motor coil, and controls the modulation rate data to get the phase difference at the best efficiency.
2.7. DC Current Detection Sensor Circuit
Control of current phase difference is made by reading in the phase difference generated at the both edges of shunt register (R100) by the compres-
sor electrifying current on the PWB through the Op-amp (IC9) to the microcomputer. This is a control to modulate up to the phase with the best effi-
ciency by comparing the phase of this input current, so called compressor electrifying current, with the compressor driving voltage. In the case that
phase difference between motor voltage and current is large (current delay is large), the control will be made by lowering the compressor modulation
rate data (compressor effective value).
Comparator output waveform
(Position signal waveform)
Terminal voltage waveform
Reference voltage
(1/2 of DC voltage)
Spiky voltage
(cancelled)
Ჷ (
Ტ Უ
Motor voltage
Voltage /Current
phase difference
Motor current
Concept chart of the current phase difference control
Best timing
Difference of current
and voltage peak
Efficiency