UPD780982 View Datasheet(PDF) - NEC => Renesas Technology

Part Name

Description

View to exact match

UPD780982

8-Bit Single-Chip Microcontrollers

NEC => Renesas Technology 

CHAPTER 1 OVERVIEW OF FUNCTIONS

1.3 V/f Control

To adjust the torque of the motor, V/f control is used to adjust the voltage (V) in line with the output frequency (f).

Figure 1-4 shows how the characteristic modulation ratio of the sample program varies with the output frequency.

The modulation ratio (sine wave amplitude)/(sawtooth wave amplitude) is such that, when equal to 1, the sawtooth

wave amplitude is equal to that of the sine wave.

Figure 1-4. Variation of Characteristic Modulation Ratio with Output Frequency

Modulation ratio

1.6

1.0

0.4

10

60

110

f (Hz)

160

After V/f modulation, if the sawtooth and sine waves do not intersect, as shown in Figure 1-5, switching is not

performed.

Figure 1-5. Generation of PWM Sine Waveform under V/f Control

V

U

W

U+

V+

W+

Remark The U–, V–, and W– phases are obtained by inverting high- and low-level waveforms of the U+, V+, and

W+ phases.

Application Note U13119EJ4V0AN

15

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