5. 120° Energizing control (digital position detection control)
This control system detects the digital position detection signal and adjusts the rate of acceleration/deceleration accordingly.
The motor’s induced voltage waveform is input to the comparator in the form of PWM-switched pulse waveform, and a position detec-
tion signal is generated as a reference voltage equaling 1/2 of 280 VDC. However, since there is no induced voltage waveform when
the PWM waveform is OFF, the microcomputer performs internal processing so that detection is enabled only when it is ON. Based on
the detected position signal, actual PWM waveform output timing is determined. Since it does not use a lter circuit, the detection ac-
curacy is high. The microcomputer performs internal processing to cancel spike voltage during the regenerative process.
Furthermore, even if the induced voltage is low, position detection is still possible, thus allowing sensor-less operation at low rotation
speed in the initial stage of operation. This reduces the starting current and improves the IPM reliability.
Comparator output waveform
(Position signal waveform)
Terminal voltage waveform
Reference voltage
(1/2 of DC voltage)
Spike voltage
(cancelled)
6. 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 efciency and phase
gap generated by the applied voltage of motor and current in the coil of motor as shown in the gure below.
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
This control is the V/F drive system independent of the location of rotor, detecting the phase difference between driving voltage phase
and line current phase owing in motor coil, and controls the modulation rate data to get the phase difference at the best efci
12PHR-N_S530612PHRN.indd 18 2013/8/7 15:42:14
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