The DC DC converter is a DC conversion device that converts the DC power to the upstream, and then converts it to another DC voltage. The commonly used DC to DC converter is a complete power system consisting of a DC DC converter module, a monitoring module and the corresponding user interface boards and DC distribution units.
In the system of a plurality of DC-DC converter modules in parallel sharing load operation, and will transform the DC voltage into 48V and 24V (or +12V, +5V) DC voltage, the output branch insurance to load output; monitoring module is responsible for the working state and the converter module and the whole system can monitor, a monitor through the system and into the communication port of RS232.
The - 48V converter module is responsible for converting DC voltage to DC voltage and 24V, consists of two parts: power circuit and control circuit. The power circuit realizes the transformation from DC input to DC output, and the control circuit provides all the control signals needed for power transformation, including feedback loop, DC signal processing, analog and switching circuit.
The power circuit mainly includes the DC input filter circuit, DC - DC converter circuit, DC output filter circuit and auxiliary power supply.
The DC input filter circuit includes anti surge device, differential mode, common mode filter and so on. In case of lightning or other high pressure surge, the varistor and transient voltage suppressor can protect the converter from shock. The difference mode filter and the common mode filter can effectively suppress the high-frequency noise generated by the module, and also make interference from the DC input power does not affect the normal operation of the module.
DC - DC converter circuit mainly includes the converter circuit and the rectifier output circuit, which is an important part of the whole transformation module.
The auxiliary power supply circuit provides the DC operating voltage for the control circuit, and also provides the DC input voltage sampling.
The control circuit mainly includes DC DC conversion control circuit, protection circuit, output voltage error amplification circuit, and digital display, alarm, communication circuit and so on.
Its working principle is: after FB (output feedback circuit) received FB pin sampling amplifier, comparing the feedback voltage VFB and set a good comparison voltage Vcomp, error voltage signal, the error voltage signal input to the PWM module, the PWM based on the error voltage to adjust the duty ratio, so as to achieve the purpose of controlling the output voltage and oscillator is the role of a triangle wave frequency PWM, triangular wave through the chopper voltage chopper, Fang Bo, MOSFET is the control of the square wave conduction time to control the output voltage.