전자의료시스템 및 실습

PWM

구 환

경희대학교 전자정보대학 동서의료공학과

PWM

• Description - PWM(Pulse Width Modulation) - 일정한 전압에 일정한 주기를 갖는 펄스 열에서 High 레벨의 펄스

폭이 사용자가 지정한 값으로 바뀌는 파형 - PWM 주기 (period) - PWM 주파수 (frequency) - Duty Cycle: 전체 주기에서 하이 레벨의 펄스 폭의 % - 아날로그 신호 레벨을 디지털 신호 레벨로 묘사하는 데 매우 유용 - PWM 의 듀티는 아날로그 신호의 에너지를 의미 - DC 모터를 제어하거나 특정 아날로그 파형을 PWM 파형으로 변환

가능

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

PWM Waveform

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

Generation of PWM Outputs Using the GP Timers

• PWM Operation - To generate a PWM output with a GP timer, a continuous up-

or up-/down- counting mode can be selected. - To set up the GP timer for the PWM operation, do the

following: 1. Set up TxPR according to the desired PWM(carrier) period 2. Set up TxCON to specify the counting mode and clock

source, and start the operation 3. Load TxCMPR with values corresponding to the on-line

calculated widths(duty cycles) of PWM pulses - TxPR = (PWM period / GP timer input clock) – 1 - Continuous up- : Asymmetric Waveform Continuous up-/down- : Symmetric Waveform

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

Compare Unit Block Diagram

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

Register Setup for Compare Unit Operation

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

PWM Circuits Block Diagram

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

Dead-Band?

• Description - 순간적이지만 H- 브리지 회로에서 쇼트 회로가 발생하는 것을 막기

위한 장치 - PWM 레벨 전환 시 약간의 지연 시간을 두어 쇼트 회로가

만들어지는 상황을 피하도록 하는 기능

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

Output Logic Block Diagram

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

Asymmetric PWM Waveform Generation

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

Symmetric PWM Waveform Generation

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea

Quadrature Encoder Pulse(QEP)

2007 Summer Seminar

Impedance Imaging Research Center, Kyung Hee University, Suwon, South Korea