中文摘要：

针对脉冲密度调制功率调节方式实现复杂的缺点，提出了基于时间分割法的串联谐振逆变电源功率调节方式，该方法可确保串联谐振逆变电源输出电压频率和幅值恒定，开关管工作在零压开通和近似零电流关断状态，开关损耗小，电源效率高；同时给出了相应的频率自动跟踪电路，详细分析了其工作原理。时间分割法功率调节方式尤其适合于负载要求串联谐振逆变电源的输出电压频率和幅值恒定的场合。电源长期运行结果表明，所提功率调节方式和频率自动跟踪电路具有简单、可靠、高效、成本低、工程应用价值高等优点。

英文摘要：

The pulse density modulation method is difficult to realize for series-resonant inverter. To overcome the shortcomings of pulse density modulation method, this paper presents a time division power modulation method,analyzes the switching modes in detail, and gives its control circuit. The time division power modulation method enables frequency and amplitude of series-resonant inverter output voltage constant. Moreover, it can achieve zero voltage switch and low turn-off loss at switch transition in all operation conditions. The time division power modulation compares pulse-density modulation with the advantages of easy realization and low cost. A simple frequency auto-tracing circuit is given, and the principle of circuit is analyzed in details. The frequency auto-tracing circuit consists of two ICs （SG3525 and CD4046）. Output current reshaping signal and switch driver signal are as phase comparator П of CD4046 input signals. Phase comparator П output voltage varies with the difference phase of the two input signals. SG3525 output frequency is determined by phase comparator П output voltage. The frequency auto-tracing circuit has an excellent phase compensation effect without measurement of the inverter output voltage. Practical engineering application results show that the time division power modulation method and frequency auto-tracing circuit have the advantages of simple to realize, excellent reliability, low cost and good engineering application value.