Voltage compensation method and device of voltage reducing circuit

1. A voltage compensation method of a voltage reducing circuit, comprising the following steps:

determining a capacitance value of each capacitor and a resistance value of each resistor in a voltage compensation circuit according to a voltage compensation expectation of the voltage reducing circuit;

determining each zero and each pole of a transfer function of the voltage compensation circuit according to the capacitance value of each capacitor and the resistance value of each resistor;

setting each capacitor and the resistor not in direct connection with the capacitor in series to have a positive temperature coefficient, and setting the resistor in direct connection with the capacitor in series to have a negative temperature coefficient, wherein the positive and negative temperature coefficients are set to enable a variable quantity, generated when a temperature change occurs, of each zero and each pole of the transfer function of the voltage compensation circuit to not exceed a predetermined fluctuation range; and

compensating voltage for the voltage reducing circuit by using the voltage compensation circuit to output a rated voltage;

wherein the voltage compensation circuit comprises resistors (Rc 1 ), (Rf 1 ), (Rf 2 ), (Rf 3 ) and capacitors (Cc 1 ), (Cc 2 ), (Cf 3 ), wherein the resistor Rf 3 and the capacitor Cf 3 are connected in series and then are connected in parallel with the resistor Rf 1 between an output voltage and an inverting input terminal of a comparator; the resistor Rc 1 and the capacitor Cc 1 are connected in series and then are connected in parallel with the capacitor Cc 2 between the inverting input terminal and an inverting output terminal of the comparator; and the inverting input terminal of the comparator is grounded through the resistor Rf 2 ;

wherein the capacitors Cc 1 , Cc 2 , Cf 3 are capacitors having a positive temperature coefficient; the resistors Rf 1 , Rf 2 are resistors having a positive temperature coefficient; and the resistors Rc 1 , Rf 3 are resistors having a negative temperature coefficient;

according to a zero-pole calculation formula of the transfer function of the compensation circuit, resistance values of themistors having a negative temperature coefficient increase when the capacitance values of the capacitors having a positive temperature coefficient decrease with temperature, so that each zero and pole of the transfer function of the compensation circuit are stabilized within a certain range.

2. The method according to claim 1 , wherein the voltage reducing circuit is a BUCK circuit.

3. The method according to claim 1 , wherein the voltage compensation circuit is a type-3 compensation circuit.

4. The method according to claim 1 , wherein the transfer function of the voltage compensation circuit has two zeros and three poles.

5. The method according to claim 4 , wherein the two zeros (FZ 1 ), (FZ 2 ) are respectively:

F

Z

⁢

⁢

1

=

1

2

⁢

⁢

π

·

R

C

⁢

⁢

1

·

C

C

⁢

⁢

1

F

Z

⁢

⁢

2

=

1

2

⁢

⁢

π

·

C

f

⁢

⁢

3

·

(

R

f

⁢

⁢

1

+

R

f

⁢

⁢

3

)

.

6. The method according to claim 4 , wherein the three poles (FP 1 ), (FP 2 ), (FP 3 ) are respectively:

F

p

⁢

⁢

1

=

0

F

p

⁢

⁢

2

=

1

2

⁢

⁢

π

·

C

f

⁢

⁢

3

·

R

f

⁢

⁢

3

F

p

⁢

⁢

3

=

1

2

⁢

⁢

π

·

R

C

⁢

⁢

1

·

C

C

⁢

⁢

2

.

7. A voltage compensation device of a voltage reducing circuit, comprising:

a voltage compensation circuit, connected with a BUCK circuit and comprising a plurality of capacitors and a plurality of resistors, wherein the capacitors and the resistors not directly connected in series with the capacitors have a positive temperature coefficient, and the resistors directly connected in series with the capacitors have a negative temperature coefficient, and the positive and negative temperature coefficients are set such that a variable quantity, generated when a temperature change occurs, of each zero and each pole of a transfer function of the voltage compensation circuit does not exceed a predetermined fluctuation range;

wherein the voltage compensation circuit comprises resistors (Rc 1 ), (Rf 1 ), (Rf 2 ), (Rf 3 ) and capacitors (Cc 1 ), (Cc 2 ), (Cf 3 ), wherein the resistor Rf 3 and the capacitor Cf 3 are connected in series and then are connected in parallel with the resistor Rf 1 between an output voltage and an inverting input terminal of a comparator; the resistor Rc 1 and the capacitor Cc 1 are connected in series and then are connected in parallel with the capacitor Cc 2 between the inverting input terminal and an inverting output terminal of the comparator; and the inverting input terminal of the comparator is grounded through the resistor Rf 2 ;

wherein the capacitors Cc 1 , Cc 2 , Cf 3 are capacitors having a positive temperature coefficient; the resistors Rf 1 , Rf 2 are resistors having a positive temperature coefficient; and the resistors Rc 1 , Rf 3 are resistors having a negative temperature coefficient;

according to a zero-pole calculation formula of the transfer function of the compensation circuit, resistance values of themistors having a negative temperature coefficient increase when the capacitance values of the capacitors having a positive temperature coefficient decrease with temperature, so that each zero and pole of the transfer function of the compensation circuit are stabilized within a certain range.

8. The voltage reducing circuit, comprising the voltage compensation device of the voltage reducing circuit according to claim 7 .