Abstract: The damped AC (DAC) technology is widely used in partial discharge detection of high-voltage cables due to its advantages of small size, lightweight, and low noise. However, the DC-DAC generators tend to cause space charge accumulation, while existing AC-DAC devices have low load capacity and they all have the deficiencies of short maintenance time of nominal voltage. To address these issues, this paper proposes a DAC generation method based on full-bridge submodule cascading and piecewise linearization of circuit. Firstly, the paper presents a circuit structure based on full-bridge submodule cascading, where the voltage of the energy storage capacitor is inverted into a square wave voltage to serve as the resonant power source for the capacitor-inductor series circuit. Then, a method based on piecewise linearization of the state equation and optimized duty cycle calculation is proposed. By controlling the power electronic switches, the entire resonance process is controlled, thereby generating flexible and diverse high-voltage AC waveforms on the capacitive test object. The effectiveness of this method is verified in the laboratory, and the defects can be successfully and accurately located in a field test on a defective 110 kV cable. This technology has broad application prospects in cable insulation state detection and defect location. Compared to existing AC-DAC technology, it significantly improves load capacity. The generated high-voltage waveforms are more diverse, making it suitable for cable insulation state detection.