W04 Electric heater function control principle
1. Soft start
PWM soft start mode, group soft start, each group starts sequentially, and staggers the peak value of the inrush current. There are 2 groups of IGBTs inside, the delay time between each group is 5~25S, and the soft start is completed within 25~50 seconds. The current waveform of the heater during soft start is as follows.
Full power soft start current-time trend graph
2. Power, temperature control
After the soft start is completed, the PTC heater will compare the actual water outlet temperature and the PTC heating power according to the outlet water temperature and the target power, and perform comprehensive adjustment of power and temperature. The specific heating control rules are as follows.
Target power = set power percentage * rated power;
Target temperature = set temperature.
The PTC heater has the following heating states.
State 1: The outlet water temperature is lower than the target temperature, and the PTC heater heats according to the target power.
State 2: When the outlet water temperature is higher than the target temperature, the heater automatically adjusts the heating power to achieve constant temperature control. The temperature control range is the target temperature +-3°C.
