When Vo is less than the minimum voltage Vomin, the logical unit outputs the constant-frequency light-to-heavy load LTH mode in the dynamic mode to enable the output to be rapidly raised to the reference voltage Vref by inputting large power and then jump out of the mode and enter the normal mode, and the initial state of the normal mode is set by the mode control module.

When Vo is greater than the maximum voltage Vomax, the logical unit outputs the constant-frequency heavy-to-light load HTL in the dynamic mode to enable the output to be rapidly dropped to the reference voltage Vref by inputting small power and then jump out of the mode and enter the normal mode, and the initial state of the normal mode is set by the mode control module.

If Vo does not change greatly, the dynamic mode is not needed, and loop control is realized through normal PI control method and mode control, which is called normal working mode.

When Vo is between Vomin and Vref, if the logical unit outputs the LTH mode in last period, then the LTH mode is outputted in the period; if the output of the logical unit is the HTL mode in last period, then the output of the logical unit is the normal mode in the period; if the output of the logical unit is the normal mode in last period, then the output of the logical unit is the normal mode in the period; when Vo is between Vref and Vomax, if the output of the logical unit is the LTH mode in last period, then the output of the logical unit is the normal mode in the period; if the output of the logical unit is the HTL mode in last period, then the output of the logical unit is the HTL mode in the period; and if the output of the logical unit is the normal mode in last period, then the output of the logical unit is the normal mode in the period.