| Brushless DC motor(BLDCM)has the advantages such as small size,high power density,flexible control,high efficiency,and good reliability.It is widely used in many fields such as electric vehicles,industrial drives,and home appliances.Based on the traditional square wave and sine wave control methods of brushless DC motors,this paper proposes two control strategies for brush drive DC motor drive based on Buck / Boost DC-DC converters.This research has important research significance for promoting the integration of the brushless DC motor drive system.First of all,this paper conducted a systematic theoretical analysis and experimental research on the traditional pairwise conduction square wave control strategy of the brushless DC motor and the sine wave control strategy based on space vector pulse width modulation.It lays a theoretical and experimental basis for the realization of the drive control of the brushless DC motor based on the boost drive power topology of the Buck / Boost DC-DC converter.Secondly,in order to realize the flexible regulation of the bus voltage and increase the controllable dimension of the brushless DC motor,the brushless DC motor square wave and sine wave control strategies are studied based on the cascaded boost drive power of the Buck / Boost DC-DC converter and the three-phase full-bridge power converter.Among them,according to the different regulation methods of bus voltage,two speed control methods of bus voltage constant voltage speed closed loop and variable voltage speed closed loop are studied.In order to verify the feasibility of the method above,the steady-state and dynamic operation experiments of the system were carried out on a 60 W brushless DC motor drive system experimental platform based on the ARM controller.The theoretical analysis and experimental comparison of the two control methods found that: 1)Although the constant voltage speed closed-loop can meet the speed closed-loop control requirements of the full speed range,the motor commutation control and speed closed-loop control are algorithmically coupled,and high-speed operation under BLDC square wave control requires a three-phase full-bridge converter of the switching devices work in high-frequency PWM mode and cannot avoid high-frequency switching losses.2)The variable voltage speed closed-loop control method can realize the decoupling of speed control and drive control without changing the basic control algorithm of the brushless DC motor,so it is more suitable for speed closed-loop control when the motor runs at high speed.Finally,the introduction of the Buck / Boost DC-DC converter will increase the number of switching device and drive circuit resources of the entire power system,resulting in a corresponding increase in the size and cost of the power system.In order to further improve the integration of the power system and reduce the introduction of additional switching devices,a BLDC integrated drive power converter topology with boost drive capability is proposed,and the bus boost control and BLDC sine wave control are studied based on the power topology mutually coupled boost integrated drive control algorithm.In order to verify the operation principle of the integrated drive power converter and the effectiveness of the coupling control algorithm,a system experiment was carried out on a 60 W brushless DC motor drive system platform based on the TMS320F28335 controller.The experimental results show that this method can realize the topology integration of the boost DC-DC converter and the three-phase full-bridge converter with the addition of only one switch.The integrated drive control strategy of the boost can satisfy the stable control of the bus voltage and motor speed closed-loop control requirements.The research of the power topology and control strategy will help to further improve the integration and control flexibility of the BLDC drive system. |
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