Abstract: With the rapid development of China’s new energy power generation system, the electrical interaction between inverters and the grid becomes more and more complex, which makes the problems of harmonic resonance, low frequency oscillation and harmonic instability increasingly prominent. The accurate measurement of impedance parameters is the main way to identify whether the system oscillates or loses stability, and the broadband impedance measurement is one of the most studied impedance measurement techniques. The overall structure design of a controllable broadband impedance measuring device based on AC-DC-AC topology is presented, and the topology design of harmonic power amplifier unit and its control strategy are introduced. Then the reason of frequency coupling caused by voltage source converter(VSC) is given, and the law of aliasing between the effective broadband response and the coupling component is discussed. Then, the frequency coupling component and the effective response of VSC are staggered to avoid overlapping by injecting the broadband disturbance alternately with an odd-even frequency multiplier. Finally, Matlab/Simulink and RT-LAB semi-physical simulation are used to verify the effectiveness and correctness of the design device and measurement method.