by a back emf e 3 and the voltage between winding 24 and ground is represented by voltage v 30 the back emf e 3 is measured because it contains information regarding the rotor position and velocity waveforms for driving an electronically commutated motor in accordance with a first embodiment of the invention are shown fig4 6 a waveform 100 represents a drive voltage v a applied to winding 20 fig1 during a control period t and a waveform 102 represents a drive voltage v b applied to winding 22 during the control period t the control period illustrated in fig4 6 corresponds to control period 5 shown in fig2 it will be understood that similar voltage waveforms are applied to other winding pairs during the other control periods as shown in fig2 fig4 represents a relatively low average motor voltage v m relatively small time t 2 fig5 represents an intermediate average motor voltage v m intermediate time t 2 and fig6 represents a relatively high average motor voltage v m relatively large time t 2 as illustrated in fig4 6 winding 20 and winding 22 are both pulsed to supply voltage v dc during a portion of control period t in particular waveform 100 includes pulse 110 and waveform 102 includes pulse 112 in fig4 6 time.