AN1661 Freescale Semiconductor / Motorola, AN1661 Datasheet - Page 2

• Manufacturer Part Number: AN1661
• Description: Low Cost Universal Motor Chopper Drive System
• Manufacturer: Freescale Semiconductor / Motorola

Application Note
2
This application note also explains how to design the software
implementation using an M68HC05 microcontroller (MCU).
Today the universal motor is the most widely used motor in home
appliances such as vacuum cleaners, washers, hand tools, and food
processors.
The operational mode, which is used in this application, is closed loop
and regulated speed. This mode requires a speed sensor on the motor
shaft. Such a sensor is usually a tachometer generator. The kind of
motor and its drive have a high impact on many home appliance features
like cost, size, noise, and efficiency. Electronic control is usually
necessary when variable speed or energy savings are required.
MCUs offer the advantages of low cost and attractive design. They can
operate with only a few external components and reduce the energy
consumption as well as cost.
This circuit was designed as a simple schematic using all features of a
simple MCU. The MCU and this board may be used in a wide variety of
applications.
The pulse-width modulation (PWM) technique is used to adjust the
voltage applied to the motor (refer to
duty cycle allows the effective voltage, seen by the motor, to be varied.
The PWM technique is often termed “chopper” because of the chopped
drive signal which is created. Compared to a phase angle drive, a
chopper drive requires a more complicated power stage with an input
power rectifier, a power switch, and a power fast diode. The advantage
is higher efficiency, less acoustic noise, and better EMC
(electromagnetic compliance) behavior.
GATE SIGNAL
Gate Signal
MOTOR VOLTAGE
50% DUTY CYCLE
Freescale Semiconductor, Inc.
dc VOLTAGE
Motor Voltage
50% duty cycle
DC Voltage
For More Information On This Product,
Figure 2. Pulse-Width Modulation Technique — Chopper
Go to: www.freescale.com
Figure
2). Modulation of the PWM’s
MOTOROLA
AN1661