Output current and input power regulation with a power converter
View Patent ↗A power converter circuit senses the output voltage (Vo) and controls the converter's duty cycle (d 1 ) to provide a steady output current (Io) or input power (Pin) in each switching cycle (T). During an initial period (Tramp), the controller provides a possibly smaller target current (Iramp) to reduce the system stress while the output voltage rises to a suitable value (InitVtar).
1. A method for controlling an average output current provided by a power converter on the converter's output terminal in a plurality of consecutive periods of time of an equal length T, wherein the average output current in any one of said periods of time is Q/T where Q is a charge provided to the output terminal said one of the periods of time, the method comprising, for at least one period of time:
(1) receiving, by a computing circuit, (i) an input-voltage-defining value which defines a sampled input voltage on the converter's input terminal, and (ii) an output-voltage-defining value which defines a sampled output voltage on the output terminal; and
(2) calculating by the computing circuit a pulse-width-defining value PW1 which defines a pulse width of a control signal in said at least one period of time, the pulse width controlling the average output current, wherein the value PW1 is calculated as a function of (i) the input-voltage-defining value, (ii) the output-voltage-defining value, and (iii) a target value for the average output current to be delivered to the output terminal in said at least one period of time;
wherein the converter is a boost converter;
wherein the value PW1 is calculated to represent the pulse width as directly proportional to (a) a square root of said target value, and (b) a square root of said length T.
2. The method of claim 1 wherein the value PW1 is not calculated as a function of any sampled values other than said sampled input voltage and said sampled output voltage.
3. A method for controlling an average input power provided by a power converter on the converter's input terminal in consecutive periods of time of an equal length T, the average input power being defined as a product of an input voltage on the input terminal multiplied by an average input current on the input terminal, wherein the average input current in any one of said periods of time is Q/T where Q is a charge provided to the input terminal in said one of said periods of time, the method comprising, for at least one period of time:
receiving, by a computing circuit, (i) an input-voltage-defining value which defines a sampled input voltage on the input terminal, and (ii) an output-voltage-defining value which defines a sampled output voltage on the converter's output terminal; and
calculating, by the computing circuit, a pulse-width-defining value PW1 which defines a pulse width of a control signal in said at least one period of time, the pulse width controlling the average input power, wherein the pulse-width-defining value PW1 is calculated as a function of:
(A) the input-voltage-defining value;
(B) the output-voltage-defining value; and
(C) at least one of:
(C1) a target value for the average input power to be provided to the input terminal in said at least one period of time;
(C2) a pulse-width-defining value PW1 for an earlier one of said periods of time which precedes said at least one of said periods of time, wherein the pulse-width-defining value PW1 for the earlier one of said periods of time was computed to provide said target value for the average input power in the earlier one of said periods of time.
4. The method of claim 3 wherein the value PW1 for said at least one of said periods of time is not calculated as a function of any sampled values other than said sampled input voltage and said sampled output voltage.
5. The method of claim 3 wherein the converter is a boost converter.
6. The method of claim 5 wherein the value PW1 for said at least one of said periods of time is calculated to represent the pulse width as directly proportional to (a) a square root of said target value, and (b) a square root of said length T.
7. A method for controlling an average output current or an average input power of a power converter in consecutive periods of time of an equal length T, the method comprising controlling the converter in a plurality of first periods of time and in one or more second periods of time preceding the first periods of time, the method comprising:
receiving, by a computing circuit, a first target value defining the average output current or the average input power for each of the first periods of time;
receiving, by the computing circuit, a second target value defining the average output current for each of the one or more second periods of time;
for each of the first and second periods of time, computing, by the computing circuit, a pulse-width-defining value PW1 which defines a pulse width of a control signal for each of the first and second periods of time, the pulse width controlling the average output current and/or the average input power for each of the first and second periods of time, wherein:
for each of the first periods of time, the pulse-width-defining value PW1 is computed to provide the first target value for the average output current or for the average input power; and
for each of the second periods of time, the pulse-width-defining value PW1 is computed to provide the second target value for the average output current,
wherein computing the value PW1 comprises, for each of the first periods of time:
receiving, by the computing circuit, (i) an input-voltage-defining value which defines a sampled input voltage on an input terminal of the power converter, and (ii) an output-voltage-defining value which defines a sampled output voltage on an output terminal of the power computer; and
calculating, by the computing circuit, the pulse-width-defining value PW1 as a function of:
(A) the input-voltage-defining value;
(B) the output-voltage-defining value; and
(C) at least one of:
(C1) the first target value for the target average input power;
(C2) the pulse-width-defining value PW1 for another one of said first periods of time which precedes said at least one of said first periods of time.
8. The method of claim 7 wherein the first target value is a target value for the average output current, and the second target value is lower in magnitude than the first target value.
9. The method of claim 7 wherein computing the value PW1 comprises:
(1) receiving, by the computing circuit, (i) an input-voltage-defining value which defines a sampled input voltage on an input terminal of the power converter, and (ii) an output-voltage-defining value which defines a sampled output voltage on an output terminal of the power converter; and
(2) calculating by the computing circuit the pulse-width-defining value PW1 as a function of:
(i) the input-voltage-defining value;
(ii) the output-voltage-defining value; and
(iii) for each first period of time, of the first target value for the average output current, and for each second period of time, of the second target value.