Control system and control method for a phase shifted full bidge charger

A control method for a phase shifted full bridge charger using a control system as below:

• the control system comprising a sampling system and a charger controller;
• wherein, the sampling system comprises an input voltage acquisition device mounted at an input terminal of the charger to acquire an input voltage, a total output voltage acquisition device and a total output current acquisition device both mounted at an output terminal of the charger to respectively acquire a total output voltage and a total output current, and a charging current acquisition device mounted at an input terminal of a storage battery to acquire a charging current;
• the charger controller comprising:
• a start and running determination unit configured to receive a total output voltage signal, a total output current signal, a charging current signal and a duty ratio, and determine whether the charger operates in a waiting state, a pre-charging state, a soft start state or a running state, and generate a corresponding state signal;
• and the running state comprises a constant-voltage running state, a total-current-limiting running state and a charging-current-limiting running state;
• a soft start control unit configured to control the charger during the soft start state of the charger;
• a running control unit configured to control the charger in the running state of the charger and determine the running state of the charger;
• the running control unit comprising:
• a mode determination unit configured to receive a total output voltage value, a total output current value and a charging current value, to determine which running state the charger operates in, and to generate a running state signal of the charger;
• a constant-voltage control unit configured to control the charger when the charger operates in the constant-voltage running state;
• a total-current-limiting control unit configured to control the charger when the charger operates in the total-current-limiting running state;
• a charging-current-limiting control unit configured to control the charger when the charger operates in the charging-current-limiting running state;
• the charger controller further comprises a smooth switchover control unit configured to receive the running state signal of the charger fed back by the mode determination unit, and a soft start state signal fed back by the start and running determination unit;
• when the charger is switched between the soft start state and the running states, the control system is smoothly switched a control unit corresponding to the soft start state or the three running states of the running control unit to control a PSFB circuit connection of the charger;
• the control method comprising the following steps:
• determining whether the pre-charging of the charger ends;
• if so, the charger comes into the soft start state, and an operation of the charger is controlled by the soft start control unit;
• determining whether the soft start of the charger ends;
• if so, the charger comes into the running state, the running control unit operates, and the smooth switchover control unit allows that a control is switched to the constant-voltage control unit;
• receiving, by the mode determination unit, the total output voltage value, the total output current value and the charging current value;
• a total output current limiting value;
• and configuring, for the mode determination unit, a set value of the charging current, a total output current limiting value, a charging current limiting value, and a reference value of the total output voltage;
• determining the running state of the charger by the above received values and set values;
• and feeding an instruction for the running state of the charger back to the smooth switchover control unit;
• in the constant-voltage running state, a constant-voltage control algorithm is used, however,
• when
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• the charger comes into the total-current-limiting running state, and the smooth switchover control unit controls the switchover to the total-current-limiting control unit;
• otherwise, when
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• the charger comes into the charging-current-limiting running state, and the smooth switchover control unit controls the switchover to the charging-current-limiting control unit;
• otherwise, the charger is still in the constant-voltage running state;
• in the charging-current-limiting running state, a charging-current-limiting control algorithm is used, however,
• when
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• the charger comes into the constant-voltage running state, and the smooth switchover control unit controls the switchover to the constant-voltage control unit;
• otherwise, when
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• the charger comes into the total-current-limiting running state, and the smooth switchover control unit controls the switchover to the total-current-limiting control unit;
• otherwise, the charger still operates in the charging-current-limiting running state;
• in the total-current-limiting running state, a total-current-limiting control algorithm is used, however,
• when
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• the charger comes into the constant-voltage running state, and the smooth switchover control unit controls the switchover to the constant-voltage control unit;
• otherwise, when
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• the charger comes into the charging-current-limiting running state, and the smooth switchover control unit controls the switchover to the charging-current-limiting control unit;
• otherwise, the charger still operates in the total-current-limiting running state;
• in the above formulas, Vout denotes the total output voltage value, Iout denotes the total output current value, Iout-ref denotes the total output current limiting value, Ibat denotes the charging current value, Ibat-ref denotes the charging current limiting value, and Vref denotes the reference value of the total output voltage.