对拖测试平台的共模回路阻抗提升控制技术

A Control Technology of Improving Common Mode Impedance for Pump-back Test Bench

中压变换器的测试面临着供电电压高、能耗大、测试平台建设成本高等问题,实验室常使用共直流母线的对拖测试平台以降低对供电和负载的要求,并通过虚拟负载的手段降低测试平台的建设成本。但由于这种测试平台共模通路阻抗较小,容易形成很大的共模电流,因而无法测试变换器采用空间矢量调制(SVM)或注入零序分量脉宽调制(PWM)的运行工况。为此,这里提出了一种提升共模回路阻抗的陪测变换器控制方法。该方法利用谐振控制抑制共模电流的低频分量,通过注入稳态分量抑制共模电流的高频分量,从而有效提高了零序分量通路的阻抗,使被测变换器可注入零序分量,测试工况更接近实际工况,并拓宽了测试范围。

Testing of medium voltage converters faces many problems,such as high voltage,high energy consumption and high cost of test platform construction.A DC-coupling pump-back test bench is introduced to reduce the requirement of grid,and virtual machine is introduced to reduce the cost of load installation.However,because the commonmode channel impedance of the test platform is small and the common-mode current is easily formed,it is impossible to test the operation condition of the converter using space vector modulation(SVM)or zero-sequence component pulse width modulation(PWM).A method is proposed to improve common mode impedance,which combine proportional integral resonance control and steady-state control.In this method,resonance control is used to suppress the low frequency component of common mode current,and steady-state component is injected to suppress the high frequency component of common mode current.Common mode voltage can be injected in the test bench by using this method,which makes test condition more reasonable and widens test scope.