基于基准频率自适应谐波准谐振控制器的宽变频逆变电源控制研究

Research on Control of Wideband Variable-Frequency Inverters Based on Harmonics Quasi Resonant Controller with Frequency Reference Adapting

360~800 Hz宽变频交流电源系统是多电飞机电力系统的主要发展方向之一。为实现宽变频中频逆变电源在包括带整流型非线性负载等工况下的宽范围谐波抑制,保证其任意基准频率下的输出电压质量,提出一种基于频率基准自适应谐波准谐振控制器的控制策略。基于滤波电感电流反馈,设计了包含数字控制延迟补偿的有源阻尼方案,以抑制输出滤波器的谐振尖峰,对电压控制器的被控对象进行校正使系统得到简化;设计并采用积分与准比例谐振相结合的基波追踪控制器以消除基波频段的稳态误差;提出基准频率自适应的补偿角度设计方法以实现谐波准谐振控制在电压环控制带宽之外的谐波抑制。在理论分析的基础上,搭建了一台300~800 Hz/600 W单相逆变器样机并进行实验测试,结果表明,采用该控制策略的逆变器能够实现宽基波频段内任意基准频率下的宽范围谐波抑制,且具有良好的稳态和动态输出特性。

With the development of more electric aircraft(MEA)and the increase of aircraft power system capability,AC power system of 360~800 Hz wide variable frequency has become one of the most important development trends due to its high reliability,high power density,and huge individual machine capability.However,since more and more electric and electronic equipment,especially nonlinear loads such as rectifiers,are applied in aircraft,the harmonics induced by those loads significantly impact the voltage quality of the aircraft grid.Unlike a 50 Hz inverter,the harmonic frequency of a medium-frequency inverter is very high,usually beyond the control band,which leads to a relatively small phase margin and great difficulty in control.Typical methods,such as repetitive control,do not satisfy the requirement when the power source frequency varies.QPR(quasi-proportional resonant)and HQR(harmonics quasi-resonant)control performs poor stability since its phase changes suddenly at the resonant frequency.The paper focuses on harmonics suppression for 360~800 Hz wide variable frequency AC power inverter,as well as the stability of the voltage controller.First,the structure of a single-phase inverter with digital control is described,and then the delay of digital control,which greatly influences control stability,is derived.Next,the stability of the control system with the application of HQR is discussed.The system phase margin is very small,even negative.Due to large frequency variation,a constant angle compensation cannot ensure the control system’s stability.To simplify the design of the voltage controller,inductor current feedback active damping with digital control delay compensation is designed,which provides a suitable stability margin and minimum phase characteristic for the controlled object and suppresses the resonance peak.Furthermore,the I(integration)+QPR control scheme is proposed to improve the tracking ability of fundamental voltage.As the frequency varies from 360 Hz to 800 Hz,for HQR,a constant angle compensation cannot guarantee the voltage controller’s stability.Accordingly,a frequency self-adapted HQR-PC(harmonics quasi-resonant with phase compensation)is proposed,compensating a specific angle for the control object to acquire a sufficient stability margin under a wide frequency reference range.After that,the stability of the control system is verified by root locus figures.The digital control implementation method of polynomial fitting of compensation angle is also given.It is indicated that the control scheme has high open-loop gain at fundamental and harmonics frequencies by open-loop frequency response,and harmonics can be suppressed with simulation verification.Finally,an experimental platform of 600 W medium frequency inverter power supply with a wide output frequency range is built.The control performance of the proposed control methods is tested with resistive and nonlinear loads,respectively.The results show that the medium-frequency inverter can output voltage with small harmonics,and the total harmonics distortion of the output voltage conforms to the industrial power supply standard under the frequency reference range.Moreover,the inverter shows excellent static and dynamic performance.