Patent application number | Description | Published |
20090096397 | RELATING TO DRIVING BRUSHLESS DC (BLDC) MOTORS - In a three phase BLDC motor the rotor position is monitored by detecting the zero crossing points of the induced back EMF signals BEMF_U, BEMF_V, BEMF_W in the phase windings U, V, W. As they are illustrated, the back EMF signals are substantially sinusoidal but they may in other situations be substantially trapezoidal. The three back EMF signals are 120° out of phase with each other. In order to accurately monitor the back EMF in a phase winding, the driving waveform for each phase U, V, W includes an undriven period P close to the expected zero crossing point. The period P can be a preset part of the driving waveform or can be an interruption of the normal driving waveform in response to suitable interrupt signals. In order to determine the zero crossing points of each back EMF signal, two (or more) samples of the back EMF are taken during the undriven period P and used to interpolate the back EMF signal to determine the zero crossing point. | 04-16-2009 |
20090218974 | DRIVING BRUSHLESS DC (BLDC) MOTORS - The driving system for a tri-polar electric motor ( | 09-03-2009 |
20110074327 | CONTROL OF SINUSOIDALLY DRIVEN BRUSHLESS DC (BLDC) MOTORS - In response to the determination or estimation of a back EMF zero crossing event for the phase, a time T | 03-31-2011 |
20110221371 | ACCURACY OF ROTOR POSITION DETECTION RELATING TO THE CONTROL OF BRUSHLESS DC MOTORS - During operation of a 3 phase BLDC motor it is driven by use of a PWM waveform applied to one of the driven phase (curve a). The other driven phase is connected thereto but no driving signal is applied (curve b). The third phase is left floating (curve c). This allows the back EMF in the third phase to be monitored for the purpose of determining rotor position by detection of zero crossing points. The rapid switching of the PWM pulses causes ringing in the back EMF signal indicated for one pulse by the ringed portions | 09-15-2011 |
20140320103 | Direct Current Control with Low E-M Emission - A switching control circuit includes driving a flow of direct current through an at least partially inductive load. The switching control circuit is adapted for adjusting a control current in order to activate and/or deactivate a flow of current to a load terminal. The system comprises a timer element for initiating at least one timed adjustment of the control current during activation or deactivation of the flow of current through a first semiconductor switch of the circuit so as to anticipate a state change of a component of the switching control circuit. The controller is adapted for determining a timing for the timed adjustment in a predictive manner. A method employs the various features of the switching control circuit. | 10-30-2014 |