Control unit for improving conversion efficiency

A control unit, configured to provide a control signal for controlling a power unit, wherein the power unit comprises:

• a first positive voltage terminal;
• a second positive voltage terminal;
• a first negative voltage terminal;
• and
• a second negative voltage terminal, wherein the first negative voltage terminal and the second positive voltage terminal are coupled to each other in a short circuit manner;
• and
• a switching element, wherein one terminal of the switching element is electrically connected to the first negative voltage terminal;
• wherein the control unit is configured to:
• receive a pulse width modulation signal, wherein a reference ground of the pulse width modulation signal is the second negative voltage terminal;
• receive a first power supply signal;
• receive a second positive voltage terminal signal;
• output a second power supply signal, wherein a voltage difference between the second power supply signal and the second positive voltage terminal signal is larger than zero;
• and
• output the control signal for controlling the switching element to be turned on or turned off, wherein a reference ground of the control signal is the second positive voltage terminal signal.