Four-quadrant output switching power supply

When the switching power supply needs to work in a first quadrant and a third quadrant, a field programmable gate array controls an input power supply and a high-speed digital-to-analog converter to be conducted, the input power supply provides driving voltage, the high-speed digital-to-analog converter outputs an analog electric signal, a PWM signal is generated through an oscillation generation circuit, and the PWM signal is output to the first quadrant and the third quadrant. The driving circuit outputs first-quadrant current and third-quadrant current by controlling the magnitude of the output voltage of the driving circuit; when the switching power supply needs to work at two or four image limits, the driving circuit is connected with the output load, the output load inputs energy to the driving circuit, the driving circuit inputs the energy to the power absorption circuit, the power absorption circuit absorbs the energy input by the output load, and therefore the four-quadrant output function is achieve