The previous slide shows InstaSPIN-BLDC with 100% duty cycle. However, it obviously can work with other duty cycle values as well and shown here is the PWM technique that is used in the first release of this technology. It is called bipolar PWMs and it is actually a four-quadrant regenerative PWM technique. Take a look at this inverter shown here and the way to be driving two phases of the motor with one phase turned off. So in this case the designer will be driving transistors one, two, three and four that represents the two phases A and B with phase C represented be transistors five and six, they are going to remain off at this time, next measure the back-EMF voltage which is present on the output of coil C. Now in order to get that back-EMF reading, one will need to know what is the reference point or the neutral node inside the motor and that is where this PWM technique really shows its advantage. So notice when transistors 1 and 4 turned on, the motor voltage, the motor current and the DC bus current is shown below. Transistor 1 is on and Transistor 4 is on and assuming for now that the ohmic losses or the voltage drops across those transistors is negligible and there is no current flowing in phase C at all. What does this mean? It means that if the load between phase A and B is balanced, that the neutral node should be sitting at exactly one-half of the power supply voltage. So, it makes it really easy to determine then what is the neutral node to actually take the reading from phase C and subtract the neutral voltage from that value. Now continue with the next segment of the PWM cycle and in this case turn transistors 1 and 4 off and turn transistors 2 and 3 on. Now, the current will continue to flow in the direction that was established previously but notice the fact that now transistors 2 and 3 are turned on, what that means is the neutral node should theoretically be at exactly half of the power supply voltage. So, it does not really matter whether transistors 1 and 4 are on or 2 and 3 are on, the neutral node voltage should not change and that makes for a very nice reference point then to take the reading off of phase C.