HEF4752VF Philips Semiconductors, HEF4752VF Datasheet - Page 5

• Manufacturer Part Number: HEF4752VF
• Description: A.C. motor control circuit
• Manufacturer: Philips Semiconductors

Philips Semiconductors
APPLICATION INFORMATION
Figure 2 shows the functional block diagram of a 3-phase
a.c. motor speed control system using a thyristorized
inverter with variable frequency output. The inverter
control signals are generated by the HEF4752V
(PWM-IC). A special feature of the PWM (Pulse-Width
Modulation) - IC is here, that the motor is supplied by
sinoidally modulated pulses, hence the resulting motor
current will approach a sine-wave with a minimum on
higher harmonics. In this way, an optimum speed drive
with high performance is obtained.
January 1995
A.C. motor control circuit
Fig.2 PWM motor speed control system using HEF4752V.
5
Furthermore, the HEF4752V contains all logic circuitry
required for this special waveform generation, so that the
amount of control circuit components is reduced
considerable. The speed drive system in Fig.2 is controlled
by the analogue control section.
The FCT and VCT clock pulse oscillators are driven in
such a way, that a fast response speed control of the a.c.
motor is obtained, depending on: the reference values for
speed; motor voltage; motor current (Limited by the
measured motor current via DCCT - d.c. current
transformer -); the increasing value of V
action.
Product specification
HEF4752V
Cb
during braking
LSI