Research And Design Of High Volatage H-Brigde Motor Drive Circuit

With the development of power electronics,power devices and BCD technology,Smart Power Integrated Circuit(SPIC)was widely used in small and medium-sized power equipments in all walks of life,which has the advantages of small size,low cost,high reliability and high integration.As the core module of SPIC,motor drive circuit has broad application and market prospects.Under the subject of green and energy-saving today,motor drive chip has become an indispensable research object in the field of integrated circuits.In this paper,a three-phase H bridge motor drive chip was designed based on the Dongbu 0.18μm BCD process.The chip has a power supply voltage of 10V-80 V and work in 120° conduction mode,which has two modes of constant voltage control and PWM control.The chip contains power circuit,logic control circuit,high and low side drive circuit,output drive circuit and protection circuits,which can be applied to the small and medium power brushless DC motor system whose motor current is less than 6A.Firstly,this paper described the basic theory of drive circuit,including working principle,mathematical model,control principle and switching characteristics.Secondly,the design idea of three-phase H-bridge drive circuit was briefly described,so as to determine the overall framework and design indicators of the drive circuit.In addition,the analysis and design of circuits were completed,including bandgap reference circuit,LDO circuit,logic control circuit,level shift circuit,output circuit and over temperature protection circuit.The functions and performances of each circuit are verified by simulation under different process and temperature conditions.At the same time,the whole circuit simulation test platform was built to complete the simulation of the syetem,that ensure the correctness of the circuit.Finally,according to the principle of layout reliability and device matching,the layout design of important circuits were completed.Firstly,this paper combined the pre-regulated circuit with the high voltage LDO circuit to provide reliable and stable power supply voltage for the internal circuit in the different condition with different temperature and process.Secondly,based on the principle of fixed bias current and capacitor differential spike current,a new two-level shift circuit with narrow pulse modulation was proposed,which has the characteristics of low power consumption,less delay and high stability,and provides reliable gate driving signals for high-side power transistors.Then,the RC oscillator with high stability and good linearity was adopted to provide 1MHz frequency for charge pump circuit to control motor for the wide frequency.Finally,a fixed-time and adaptive dead-time generation circuit was used in the gate drive circuit,so that the PMOS and NMOS controlled by the same signal have definite cross conduction time,which ensures the high reliability of the circuit.The three-phase motor driver chip is applied to the motor drive system,and the function and performance simulation of the whole motor drive chip are completed based on the H_PWM-L_ON control mode.The simulation results show that,the motor current is 3.82 A under typical conditions.Power up time is 80μs and shut current is 9.6μA.Supply current is 6.74 m A,the source current is 208 m A,and the sink current is 228 m A.In order to study the variable speed motion of the motor,various factors affecting motor current are discussed and studied.The results show that the motor current can be adjusted by changing the power supply voltage,PWM frequency,PWM duty cycle and motor load to achieve variable speed control of the motor.The designed three-phase H-bridge motor drive chip is simple and practical,and can be well used in high voltage motor drive system.