The Studying Of The High Reliable Phase-changing Control Of BLDCM Driving Circuits

At present, the advent of information and digital technologies, the elevatedintegration density of electronic components resulting in the miniaturized consumerelectronics, give priority to the solution of electronic products’ cooling issues. Thereforethe BLDC cooling motors have been widely used. However domestically, thephase-changing control of BLDCM driving circuits is still rarely spoken. Andinternationally, this field is mostly dominated by two or three companies, like Rohm,Sanyo in Japan, etc. Therefore studying the phase-changing control of BLDCM drivercircuits can accept important academic and practical values.This thesis mainly studies the high reliable phase-changing control of BLDCMdriving circuits. By analyzing the operating principles of BLDCM, the thesis mainlystudies the high reliable phase-changing control method of BLDC motor driving circuits.It mainly includs that: the generation and suppression principle of kickback voltage，andthe suppress method during the phase-changing; Studying the phase-changing controlby the soft switching method. And promotes the novel suppress circuits of kickbackvoltage and the phase-changing control of soft switching. And the following noveltechnologies have been presented:①A new inductive kickback voltage absorption scheme (KAC Circuits: IEEET-IE,2012.02) is proposed. The scheme adopts a high speed comparator to detectinductive kickback voltage. Once detected, the comparator will generate logic controlsignals and control power H-bridge to absorb the kickback voltage by recirculating theindutive current. The scheme is fully integrated in the driving IC and no need externalpower zener diodes and large capacitors. It used for single phase BLDCM drivingcircuits with built-in power devices. The proposed kickback absorption scheme has beenrealized on a UMC0.6μm18V2P2M BCD process. And test result shows that thekickback voltage of power supply is more than4.9V without absorbing circuits, and thevoltage is just1.5V with the proposed circuits.②A new driving topology to suppress the kickabck voltage (Electronics andSignal Processing,2011.06) is proposed. By adopting a power isolation circuit, the new topology can auto-control the external H-bridge to suppress the kickback voltagewithout large capacitors, power zener diodes, and it also no need the high speedcomparator. Furthermore, all the devices used in the new driving topology are availablein the ordinary topology. It used for single phase BLDCM driving circuits with externalpower devices. The new driving topology has been verified in the driving IC withexternal power devices. And test result shows that the kickback voltage of power supplyis more than30V with ordinary topology, and the voltage is just4.0V with the newtopology.③A high precision zero temperature coefficent current reference has beenpresented in the thesis. The proposed current reference with on-chip resistors is currentmode. And trading off the resistor’s temperature coefficient, area and the changing rateof the current reference, we choose P+diffusion resistor in it. And the reference hasbeen successfully verified on a UMC0.6μm18V2P2M BCD process. The experimentalresults have confirmed that a maximum temperature coefficient74ppm/K could beobtained at power supply3.3V from-40℃to85℃and power supply sensitivity are0.27%at-40℃,0.27%at25℃and0.39%at85℃from2.2V to5.5V, respectively.④Propose the phase-changing control of BLDCM driving circuits with the softswitching method. Based on the priceples, the thesis studies two ways. The first is thesoft switching comparator circuits, and it mainly used for phase-changing of BLDCMdriving circuits. The second is PWM mode soft switching phase-changing method. Thetwo ways above have been successfully verified in UMC0.6μm18V2P2M BCD andUMC0.6μm5V2P3M BiCMOS processes, respectively. And they have been fullyintegrated in the BLDCM driving IC.