“AIST”Tools—Make Work Efficient
DC chopper is the conversion of fixed DC voltage into variable DC voltage, also known as DC/DC transformation.
Chopper there are two ways of working, one is the pulse width modulation mode, Ts (cycle) is constant, change the Ton (general, Ton to switch every time on time), the second is the frequency modulation way, Ton is constant, change the Ts (prone to interference).
The specific circuits are as follows:
1. Buck circuit: voltage reducing chopper, the output average voltage Uo is less than the input voltage Ui, and the output voltage is of the same polarity as the input voltage.
2. Boost circuit: Boost chopper, whose output average voltage Uo is greater than the input voltage Ui, and the output voltage has the same polarity as the input voltage
3. Buck-boost circuit: voltage reduction or Boost chopper, whose output average voltage Uo is greater than or less than the input voltage Ui, and the output voltage has the same polarity as the input voltage and inductance transmission.
4. Cuk circuit: voltage-reducing or voltage-boosting chopper, whose output average voltage Uo is greater than or less than the input voltage Ui, the output voltage is opposite to the input voltage polarity, and capacitor transmission.
Using dc chopper instead of rheostat can save energy (20~30 %). Dc chopper can not only play the role of regulating voltage (switching power), but also can play an effective role in suppressing the harmonic current noise on the power grid side.
The soft switch technology has made a qualitative leap, happened to the DC/DC United States VICOR ECI companies design and manufacture of a wide range of soft switch DC/DC converter, the maximum output power is 300 W, 600 W, 800 W, etc., the corresponding power density for (6, 2, 10 and 17) W/cm ^ 3, the efficiency for (80-90) %. NemicLambda Japanese company newly launched a new soft switch technology of RM series high frequency switch power supply module, the switching frequency is (200-300) kHz, power density has reached 27 w/cm ^ 3, the synchronous rectifier (MOS FET instead of schottky diode), the whole circuit efficiency to 90%.