Synchronous motor excitation control system and method and refrigeration equipment

The invention discloses a synchronous motor excitation control system and method and refrigeration equipment, a direct current driver, a direct current operation power supply and a main controller, the direct current driver and the direct current operation power supply are both connected with the main controller, and the direct current driver is in excitation connection with a synchronous motor and is used for providing excitation current for the synchronous motor; the DC operation power supply comprises a rectification module, a storage battery and an operation switch, the rectification module and the operation switch are connected with the main controller, the storage battery is connected with the rectification module in parallel, the input end of the rectification module is externally connected with AC commercial power, and the output end of the rectification module is in excitation connection with the synchronous motor through the operation switch; the main controller is used for obtaining the running sta