PWM direct transmission through RF for motor speed and direction controlling Syed Ahsan Ali(1) Umar Farooq(2) and Muhammad Ihtesham Adil(3) Department of Electrical Engineering Department of Electrical Engineering Sharif college of engineering and technology raiwind road Lahore. Sharif college of engineering and technology raiwind road Lahore. ahsan_zanjani@hotmail.com(1) ch.umarfarooq94@gmail.com (2) ihtesham.adil@sharif.edu.pk (3) Abstract - In this paper we are controlling the speed of DC Motor wirelessly through PWM technique through an 8051 microcontroller. The microcontroller is controlling the speed and changing direction of motor according to the instruction given by the user. At transmitter side PWM is generated from microcontroller with variable duty cycle at different frequencies and send it through RF directly and a microcontroller at receiver side will decode the pulses and control the speed of DC motor. Keyword - RF, PWM, Motor Speed Control, Wirelessly Motor Control I. INTRODUCTION In this paper we are using DC motor instead of others because these motors are playing competent role in the industries. These are widely used in industries due to its low cost, less complex control structure and wide range of speed and torque. Besides these motors are providing high starting torque which is required for traction applications. DC motors are used in portable machine tools supplied from batteries, in automotive vehicles as starter motors, blower motors, and in many control applications as actuators and as speed and position sensing devices. In this paper we are basically controlling the speed of motor. There are mainly three methods to control the speed of motor namely field control method, armature voltage control method and armature resistance control method. In general, armature voltage control method is widely used to control the DC drives. The technique which we are using in this paper to control the speed of motor is pulse width modulation(PWM).In this paper the source of PWM is through microcontroller which is not connected directly to the motor because the starting current of motor is much high so microcontroller can be damaged. To avoid this we are using optocoupler between microcontroller and motor for protection .To control the direction of DC motor we are using the H-bridge. In this paper we are using RF system which gives signal to microcontroller to control the direction and speed of motor. Joshi et al. explained Speed Control of DC motor Using Analog PWM technique which eased the use of Dc motor movement used in many applications [1]. Sandhya et al. explained Industrial Automation through RF Base Multi Channel Wireless Remote Controller which helps in controlling the speed and direction of DC and A.C motors in bidirectional [2]. Roslin et al. explained the Brushless DC Motor Control Using Digital PWM Techniques which reduces the complexity of motor control hardware as well as increases the efficiency and reliability.[3] Hemanand et al. explained the Speed Control of Brushless DC Motor Drive Employing Hard Chopping PWM Technique Using DSP which helps in controlling the speed of DC motor.[4] Abdelhamid explained the Performance of Single-phase DC Drive System Controlled by Uniform P WM Full Bridge DC-DC Converter which gives fast response to control the DC motor.[5] In this work speed of dc motor has been controlled through PWM technique through microcontroller. System has been designed using RF transmitter, RF receiver, microcontroller, optocoupler voltage regulator, LCD and12V battery. All components are easily available in the market. The system which has been designed is highly accurate and efficient. II. System Design A. RF System RF (300-440MHz) system is use as wireless system, its use only for given the instruction to microcontroller. This system consists of switches which gives signals to encoder i.e. PT2262 that encodes the signal and given it to RF transmitter module which transmits the signal to surrounding as shown in Fig 1. To receive this signal we are using the RF receiver Module which gives signal to decoder i.e. PT2272. It decodes the signal and does certain pin high according to the signal as shown in Fig.2 B. MICROCONTROLLER We are using 89C51 programmable microcontroller chip, which has been burned with program. It works according to this program. It takes instruction from decoder and gives response according it as shown in Fig 2. C. Optocoupler It has been used for insulation purpose between microcontrollers and motors on industrial level because starting current of motor is much high and due to high current our microcontroller will be damaged. Because of this we are using optocoupler 4N35.