Modeling and Simulation of Cost Effective Sensor Less BLDC Motor Drive for Electric Vehicle Applications

This proposed paper is to model and simulate the sensor less control of Brushless DC motor with four switch three phase inverter. Here, a new structure of three phase inverter with reduced number of swi (i.e. four-switch) for BLDC drive is introduced to reduce the switching losses that occur in the six switch method and eliminate the mechanical commutation. Conventionally used hall sensors for position detection increase the size of the motor and are temperature sensitive since they are mounted inside. So sensor is eliminated and the back emf method is adopted for switching. The zero point can be detected and it is used to commutate a motor thereby increasing the overall efficiency.


I. INTRODUCTION
Brushless DC Motors (BLDC) drives are nowadays widely used for various purposes in consumer products and industrial applications. It is attracting much interest due to its high efficiency, high power factor, high torque, simple control, and lower maintenance. An inverter-driven three motor needs rotor position information to ensure stable operation by synchronizing the phase excitation to the rotor position. This information is generally available by using position sensors. But it is not desirable to use position sensors for applications where reliability is of utmost importance because a sensor failure may cause instability in the control system. This proposed paper is to model and simulate the sensor less control of Brushless DC motor with fourswitch three phase inverter. Here, a new structure of three phase inverter with reduced number of switches switch) for BLDC drive is introduced to reduce the switching losses that occur in the sixswitch method and eliminate the mechanical commutation. Conventionally used hall sensors for position detection increase the size of the motor and e temperature sensitive since they are mounted inside. So sensor is eliminated and the back emf method is adopted for switching. The zero-crossing point can be detected and it is used to commutate a motor thereby increasing the overall efficiency.

k EMF, Zero Crossing
Brushless DC Motors (BLDC) drives are nowadays widely used for various purposes in consumer products and industrial applications. It is attracting much interest due to its high efficiency, high power factor, high torque, simple control, and lower driven three-phase BLDC motor needs rotor position information to ensure stable operation by synchronizing the phase excitation to the rotor position. This information is generally . But it is not e to use position sensors for applications where reliability is of utmost importance because a in the control

II. PROBLEMS WITH SENSORED AND SIX SWITCH INVERTERS
Conventional BLDC motor drives are implemented via a six-switch three three Hall Effect position sensors and two current sensors that generate proper si commutation. These sensors h drawbacks. Position sensor especially Hall se increases the size of the motor and are temperature sensitive since they are mounted inside thus limits the operation of the motor in practice. the cost of the motor and require special mechanical arrangements to be mounted. In add reduce the system reliability because of their extra components and wiring. In this project, a cost effective position sensor less control for four three-phase BLDC motor drive using a single current sensor is proposed.  Losses. In additional to that with the normal three phase voltage-source inverter with Four most important descriptions of this proposed converter plays dual role, i) the first is the reduction of Switches and Freewheeling diode count; ii) the second is the reduction of conduction losses.

Fig. 2 Four Switch three phase inverter
In proposed method single phase to three phase converters back end consists of four switches (T1 to T6). In three phase Brushless DC motor, two phases A and B are connected to the two legs of the Four switch three phase inverter and the third phase C is connected to the centre point of the capacitor. Phase C is directly connected to the Brushless DC motor, so the phase C current is not directly controlled Sa + Sb + Sc =0 Sc=-(Sa + Sb) Therefore, phase C indirectly controlled by phase A and phase B. For Brushless DC motors with a trapezoidal back EMF, is required to produce a constant electric torque. The proposed voltage Pulse Width Modulation (PWM) scheme for Four three phase inverter requires six commutation modes which are (X, 0), (1,0), (1, X), (X, 1), (0, 1) and (0, Here "X" stands for don't care conditions. Losses. In additional to that with the normal threesource inverter with Four switches, the most important descriptions of this proposed i) the first is the reduction of Switches and Freewheeling diode count; ii) the second is the reduction of conduction losses. proposed method single phase to three phase back end consists of four switches (T1 to three phase Brushless DC motor, two phases A and B are connected to the two legs of the Fourphase inverter and the third phase C is cted to the centre point of the capacitor. Phase C to the Brushless DC motor, so the phase C current is not directly controlled. (1) (2) Therefore, phase C indirectly controlled by phase A B. For Brushless DC motors with a back EMF, is required to produce a constant electric torque. The proposed voltage Pulse Width Modulation (PWM) scheme for Four-switch three phase inverter requires six commutation modes (1, X), (X, 1), (0, 1) and (0,X). care conditions.
(4) Vb = 3/2ew+ Vdc/2 (5) Vc = 3/2ew+ Vdc/2 (6) In these equations, forward voltage drop of Insulated bipolar transistor and freewheeling diode is ignored. tch converter based on the operation, the generation of 120˚ conducting current profile is essentially complicated. That resource the conventional Pulse width modulation schemes

VI. CONCLUSION
Brushless DC drives is preferable for compact, low maintenance and high reliability system reduce the mechanical strength it proposed without sensors and simulations were simulation of the brushless DC motor is done using the software MATLAB/SIMULINK phase voltage, phase current, rotor speed waveform are analysed for the speed of rotor is 800 rpm. In this proposed converter uses less number of bipolar switches which evaluate the conventional converter. The back electromotive force compensating and direct current controlling for brushless DC motor drive was leg failure was avoided. P is preferable for compact, low maintenance and high reliability systems. In order to reduce the mechanical strength it proposed that without sensors and simulations were carried out. The simulation of the brushless DC motor is done using the software MATLAB/SIMULINK. Back EMF, phase current, rotor speed waveforms the speed of rotor is 800 rpm. In this less number of insulated bipolar switches which evaluate the difference from he back electromotive force compensating and direct current controlling for was analysed and switch Pulse width modulation International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456 @ IJTSRD | Available Online @ www.ijtsrd.com scheme can eradicate the offset voltage in the back electromotive force signal caused by the voltage drop of the insulated bipolar transistor and also increase system efficiency by reducing the conduction loss is achieved. There are no hall sensors and system becomes robust, optimized design, efficiency and better speed.