Power conversion device and control method therefor

1 . A power conversion device comprising:

an input terminal;

an output terminal;

a DC/DC converter that is connected to the input terminal and the output terminal and includes a conversion circuit that convers direct-current power, wherein the conversion circuit includes a switching element; and

a control circuit that detects a first voltage at the output terminal, a first current flowing through the conversion circuit, and a second voltage at the input terminal, obtains information indicating a target output voltage and a predetermined voltage, and performs a plurality of calculations to emit a pulse width modulation (PWM) signal for driving the switching element, wherein

the control circuit:

performs a first calculation for calculating a target current for approximating the first voltage to the target output voltage;

performs a second calculation for calculating a first duty ratio for approximating the first current to the target current;

performs a third calculation for calculating a second duty ratio based on the predetermined voltage and the second voltage;

performs a fourth calculation for calculating a driving duty ratio of the PWM signal using the first duty ratio and the second duty ratio;

controls the first voltage by emitting the PWM signal having the driving duty ratio; and

calculates the driving duty ratio using a product of the first duty ratio and the second duty ratio in the fourth calculation.

2 . The power conversion device according to claim 1 , wherein

the control circuit calculates the driving duty ratio using a sum of the first duty ratio and the second duty ratio in the fourth calculation.

3 . The power conversion device according to claim 1 , wherein

the DC/DC converter includes first to Nth conversion circuits connected in parallel, the first to Nth conversion circuits each being the conversion circuit, N being an integer, and

the control circuit:

calculates the driving duty ratio for each of the first to Nth conversion circuits; and

controls the first voltage by emitting, to a corresponding one of the first to Nth conversion circuits, the PWM signal having the driving duty ratio calculated.

4 . The power conversion device according to claim 1 , wherein

the control circuit performs the first calculation, the second calculation, the third calculation, and the fourth calculation upon receipt of a start signal from outside the power conversion device, and controls the first voltage by emitting the PWM signal having the driving duty ratio.

5 . The power conversion device according to claim 1 , wherein

the predetermined voltage is the target output voltage.

6 . A power conversion device comprising:

an input terminal;

an output terminal;

a DC/DC converter that is connected to the input terminal and the output terminal and includes a conversion circuit that convers direct-current power, wherein the conversion circuit includes a switching element; and

a control circuit that detects a first voltage at the output terminal, a first current flowing through the conversion circuit, and a second voltage at the input terminal, obtains information indicating a target output voltage and a predetermined voltage, and performs a plurality of calculations to emit a pulse width modulation (PWM) signal for driving the switching element, wherein

the control circuit:

performs a first calculation for calculating a target current for approximating the first voltage to the target output voltage;

performs a second calculation for calculating a first duty ratio for approximating the first current to the target current;

performs a third calculation for calculating a second duty ratio based on the predetermined voltage and the second voltage;

performs a fourth calculation for calculating a driving duty ratio of the PWM signal using the first duty ratio and the second duty ratio;

controls the first voltage by emitting the PWM signal having the driving duty ratio; and

calculates, in the second calculation, a temporary duty ratio by performing a predetermined calculation using the first current and the target current, and when the temporary duty ratio calculated exceeds a predetermined maximum value, the control circuit outputs the predetermined maximum value as the first duty ratio.

7 . The power conversion device according to claim 6 , wherein

the control circuit calculates the driving duty ratio using a sum of the first duty ratio and the second duty ratio in the fourth calculation.

8 . A control method for a power conversion device, wherein

the power conversion device includes:

an input terminal;

an output terminal;

a DC/DC converter that is connected to the input terminal and the output terminal and includes a conversion circuit that converts direct-current power, wherein the conversion circuit includes a switching element; and

a control circuit that detects a first voltage at the output terminal, a first current flowing through the conversion circuit, and a second voltage at the input terminal, obtains information indicating a target output voltage and a predetermined voltage, and performs a plurality of calculations to emit a pulse width modulation (PWM) signal for driving the switching element,

the control method comprising:

performing, by the control circuit, a first calculation for calculating a target current for approximating the first voltage to the target output voltage;

performing, by the control circuit, a second calculation for calculating a first duty ratio for approximating the first current to the target current;

performing, by the control circuit, a third calculation for calculating a second duty ratio based on the predetermined voltage and the second voltage;

performing, by the control circuit, a fourth calculation for calculating a driving duty ratio of the PWM signal using the first duty ratio and the second duty ratio;

controlling, by the control circuit, the first voltage by emitting the PWM signal having the driving duty ratio; and

calculating, by the control circuit, the driving duty ratio using a product of the first duty ratio and the second duty ratio in the fourth calculation.

9 . The power conversion device according to claim 6 , wherein

the DC/DC converter includes first to Nth conversion circuits connected in parallel, the first to Nth conversion circuits each being the conversion circuit, N being an integer, and

the control circuit:

calculates the driving duty ratio for each of the first to Nth conversion circuits; and

controls the first voltage by emitting, to a corresponding one of the first to Nth conversion circuits, the PWM signal having the driving duty ratio calculated.

10 . The power conversion device according to claim 6 , wherein

the control circuit performs the first calculation, the second calculation, the third calculation, and the fourth calculation upon receipt of a start signal from outside the power conversion device, and controls the first voltage by emitting the PWM signal having the driving duty ratio.

11 . The power conversion device according to claim 6 , wherein

the predetermined voltage is the target output voltage.