Based on multi-frequency shift, a novel technology was proposed for controlling gradient amplifier in magnetic resonance imaging. Phase-locked-loop (PLL) circuit was used to achieve phase shift, and insulated-gate bipolar transistor (IGBT) full-bridge to achieve parallel output current and output power inductor. An output negative feedback system and average current control on every bridge were used to achieve high power, low ripple and low noise current output for the amplifier. The technology was validated on a custom-made gradient amplifier.%提出了一种基于倍频移相的梯度放大器控制技术，该系统利用PLL形成相位差通过 IGBT 全桥拓扑结构以及输出功率电感并联电流输出。通过输出端闭合反馈系统和各个桥臂的均流控制反馈，实现大功率、低纹波、低噪声的电流输出。将该控制方法用于自主研制开发的梯度放大器上进行实验验证，测试得到的电流精度、纹波、噪声均达到指标要求，结果证明该设计方案具有可行性。
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