In the resonant transformerless switching-mode power supplies （TLSMPS）

the method of switchoff in the duration of zero current is applied. Consequently

as compared with chopper （PWM） type TLSMPS

it is possible to avoid the second breakdown

reduce the switching dissipation and radio frequency interference in the resonant TLSMPS.The operation of the power circuit of resonant TLSMPS is analyzed mathematically and the features of control are discussed in this paper. For solving the problem of stabilization in the control system of resonant TLSMPS

the technique of "forward" ripple feedback is proposed. Also

the existence of minor carrier storage effect in switching transistor of resonant loop is illustrated

and the impact of this effect is reduced.