A current mode control dcdc boost converter and its pulse frequency modulation method
A technology of changer and current mode, which is applied in the direction of control/regulation system, conversion of DC power input to DC power output, and adjustment of electrical variables, etc. It can solve problems such as large ripples, simplify the system structure, and reduce the size of ripples. , Reduce the effect of integration difficulty
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Embodiment 1
[0039] Such as Figure 2A Shown is the circuit diagram of Embodiment 1 of the DCDC boost converter of the present invention. The DCDC step-up converter includes a DCDC step-up circuit and its control circuit.
[0040] The general structure is the same as that of a general DCDC step-up circuit, and the main components of the step-up circuit of the present invention are as follows: the DC power supply voltage is V BAT , the output voltage at the load terminal is V O , the master switch is SW1, the slave switch is SW2, L is the inductance, and RL is the load resistance.
[0041] Inside the dotted box is the control circuit of the DCDC step-up converter of the present invention, including a control unit 210 , an inductor current holding unit 220 , and an output voltage comparison unit 230 . The function and structure of each unit are as follows:
[0042] The control unit 210 receives signals from the inductor current holding unit 220 and the output voltage comparison unit 230,...
Embodiment 2
[0059] Such as image 3 Shown is the circuit diagram of Embodiment 2 of the DCDC step-up converter of the present invention. Depend on Figure 2B It can be seen that the output voltage V of the DCDC step-up converter of the basic structure of Embodiment 1 O with reference voltage V ref There is a slight deviation (this deviation is less than the V at the steady state of the system O ripple). If required V O exactly equal to V ref A further improvement can be made on the basis of Embodiment 1, and an error amplifier (Error Amplifier2) 232 and a compensation capacitor Cc are added to the output voltage comparison unit 230 . Using the high gain of the error amplifier and the negative feedback structure of the whole system, the output voltage Vo can be set to be exactly equal to V ref . Capacitor Cc is used to increase the stability of the converter negative feedback loop. This embodiment is suitable for applications requiring V O exactly equal to V ref occasions.
Embodiment 3
[0061] Figure 4 It is the circuit diagram of Embodiment 3 of the DCDC step-up converter of the present invention.
[0062] This embodiment is further improved on the basis of Embodiment 1, and a current comparator 223 is used in the inductor current holding unit 220 to replace the inductor current comparator 222 and the zero-crossing comparator 221 of Embodiment 1. The current comparator 223 has two switches SW3 and SW4, wherein SW3 is connected to 0 current, and SW4 is connected to the reference current I ref connected. The inductor current I can be compared by turning on or off SW3 and SW4 L with reference current I ref The size of the sensor, or the detection of the inductor current I L Whether to drop to 0.
[0063] When SW1 is turned on and SW2 is turned off, the control unit 210 outputs a signal to make the control switch SW4 turn on and SW3 is turned off, and the current comparator 220 compares the inductor current I L with reference current I ref size, when I ...
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