A resonant power converter, comprising: a switch circuit , a resonant tank , a transformer , and a rectifier circuit connected sequentially, wherein the switch circuit is adapted to receive an input voltage (Vin) from an input source , and the rectifier circuit is adapted to output an output voltage (Vout) to a load ; and a current synthesizing module , comprising: a sensing circuit configured to sense a resonant capacitor voltage (Vcr) on a resonant capacitor of the resonant tank ; a peak hold circuit electrically connected to the sensing circuit for receiving the resonant capacitor voltage (Vcr), wherein the peak hold circuit is configured to acquire a peak value (Vcr_ph) of the resonant capacitor voltage (Vcr); and a calculation unit electrically connected to the peak hold circuit , wherein the calculation unit is configured to receive the peak value (Vcr_ph), a switching frequency (Fsw), the input voltage (Vin), the output voltage (Vout), and a resonant capacitance (Cr) of the resonant capacitor of the resonant power converter and generate a synthesized output current (lout) accordingly based on an equation: Iout = K ∗ Vin ∗ Fsw ∗ Cr ∗ 2 ∗ Vcr _ ph − Vin Vout where Iout is the synthesized output current, K is an efficiency coefficient, Vin is the input voltage, Fsw is the switching frequency, Cr is the resonant capacitance, Vcr_ph is the peak value, and Vout is the output voltage. a switch circuit , a resonant tank , a transformer , and a rectifier circuit connected sequentially, wherein the switch circuit is adapted to receive an input voltage (Vin) from an input source , and the rectifier circuit is adapted to output an output voltage (Vout) to a load ; and a current synthesizing module , comprising: a sensing circuit configured to sense a resonant capacitor voltage (Vcr) on a resonant capacitor of the resonant tank ; a peak hold circuit electrically connected to the sensing circuit for receiving the resonant capacitor voltage (Vcr), wherein the peak hold circuit is configured to acquire a peak value (Vcr_ph) of the resonant capacitor voltage (Vcr); and a calculation unit electrically connected to the peak hold circuit , wherein the calculation unit is configured to receive the peak value (Vcr_ph), a switching frequency (Fsw), the input voltage (Vin), the output voltage (Vout), and a resonant capacitance (Cr) of the resonant capacitor of the resonant power converter and generate a synthesized a sensing circuit configured to sense a resonant capacitor voltage (Vcr) on a resonant capacitor of the resonant tank ; a peak hold circuit electrically connected to the sensing circuit for receiving the resonant capacitor voltage (Vcr), wherein the peak hold circuit is configured to acquire a peak value (Vcr_ph) of the resonant capacitor voltage (Vcr); and a calculation unit electrically connected to the peak hold circuit , wherein the calculation unit is configured to receive the peak value (Vcr_ph), a switching frequency (Fsw), the input voltage (Vin), the output voltage (Vout), and a resonant capacitance (Cr) of the resonant capacitor of the resonant power converter and generate a synthesized output current (lout) accordingly based on an equation: Iout = K ∗ Vin ∗ Fsw ∗ Cr ∗ 2 ∗ Vcr _ ph − Vin Vout where Iout is the synthesized output current, K is an efficiency coefficient, Vin is the input voltage, Fsw is the switching frequency, Cr is the resonant capacitance, Vcr_ph is the peak value, and Vout is the output voltage. <EOS>