If you send commutation sequence at very low speed, BLDC motor will behave like Step-Motor. It will make an advance to next position, then stop and wait for next sequence. When it stops there wont be any back-emf and current at windings can be high. To keep it under allowed limit, PWM duty cycle should be set accordingly. 

Since in your case motor is running, but heating up, maybe you can try same code with lower PWM duty cycle. To increase the speed you will increase the PWM duty cycle. This way you can control the speed at startup until you get enough back-emf if it will be used for sensor-less control. 

During experiments, It is best to start from very low speeds (where you can observe advance steps) and increase it slowly until motor will be able to follow the sequence. 

Thankyou for your response but I already check with lower and higher PWM duty cycle at high side of mosfet . and iam applying PWM duty cycle.my mosfet switching periods are 

T1,T6

T1,T5

T3,T5

T3,T4

T2,T4

T2,T6

and iam providing delay sequence  T1,T6 TO T1,T5 repeting milliseconds using arduino controlling by pot ,sequence will repeated using  loop.

give me any suggestion will coding and hardware point.

3phase inverter diagram  is

If channel 0 ADC0 is meant for controlling the PWM dutty cycle, I did not see any change at PWM signals that drive motor when I changed control voltage (from zero to max) at this input from simulation circuit when running simulation. 

Maybe freezing one state and measuring PWM duty at logical control pins, in simulation or in real with oscilloscope. 

Also to note that there are two free parameters to control when doing open-loop control in this case: first, PWM duty cycle that will control motor winding current, and second, speed of sequence delivering that will control the "steps" of BLDC. Until some speed these two quantities are independent, so for testing purpose it is best to have two control inputs, one for PWM duty by potentiometer and other for sequence speed, again with potentiometer at other ADC channel or with keys (up and down). 

in my practical observation iam checking this two stages

STAGE 1:  individual control  using potentiometer connected ADC0 at PWM and ADC1 at switching  sequence  

STAGE2: both pwm and switching sequence  speed control at a time by  taking pot connected to ADC0.

PROBLEMS FACING:

1) at this two stages  iam observing at simulation and experimental time 3 phase  signals disturbed and i will not getting perfect wave form.

2)motor will not rotate at  high speed at at load  and noload conditions(EX:if motor maximum speed 5000 rpm it will run at 1500 to 2000 rpm).

3)motor getting heated at running time. 

4) at  the hard ware mosfet driver circuit using IR2110  there is boot strapping capacitor is connected across VB  and VS and the capacitor selection impotent

and   it is not matching with our generating frequency(problem facing at aboot strapping capacitor). 

Try using 3 separate power supplies for driving upper stages (VB-VS) without using boot strapping. This way you can go down to 0 frequency for sequence switching. This can overcome problems of 1 and 4. 

If motor has not finished previous step and it gets next sequence it can get backward moments, and after some sequence speed it will not keep movement in sync with driving sequence. Situation gets worse with load, because of increased inertia. This is related to point 2. Above some speed feedback will necessary, be it sensor or sensor-less. 

Also, slopes of PWM and of sequence can be (and usually are) different. 

For point 3, main point to search the problem is PWM duty cycle (and maybe motor supply voltage, or type of motor, is it constructed for forced air cooling or not). Try with constant low sequence frequency, e.g. 2 second/step, and by potentiometer control PWM duty from 0 to some higher value, while observing motor advancing, output voltages, and maybe winding currents. Also motor heating after prolonged run time for different PWM duties.