Systems and methods for output current regulation in power conversion systems

A system controller for regulating a power converter, the system controller comprising:

• a driver configured to output a drive signal to a switch to affect a current flowing through an inductive winding of a power converter, the drive signal being associated with a switching period including an on-time period and an off-time period;
• and
• a controller terminal configured to receive a first signal related to an input signal of the power converter;
• wherein:
• the switch is closed in response to the drive signal during the on-time period;
• the switch is opened in response to the drive signal during the off-time period;
• a duty cycle is equal to a duration of the on-time period divided by a duration of the switching period;
• and
• one minus the duty cycle is equal to a parameter;
• wherein the system controller is configured to keep a multiplication product of the duty cycle, the parameter and the duration of the on-time period approximately constant;
• wherein the system controller is configured to keep a multiplication product of the duty cycle, the parameter and the duration of the on-time period approximately constant so that an average of the current during one or more switching periods increases in magnitude with the increasing input signal over time and decreases in magnitude with the decreasing input signal over time.

A system controller for regulating a power converter, the system controller comprising:

• a driver configured to output a drive signal to a switch to affect a current flowing through an inductive winding of a power converter, the drive signal being associated with a switching period including an on-time period and an off-time period;
• and
• a controller terminal configured to receive a first signal related to an input signal of the power converter;
• wherein:
• the switch is closed in response to the drive signal during the on-time period;
• the switch is opened in response to the drive signal during the off-time period;
• a duty cycle is equal to a duration of the on-time period divided by a duration of the switching period;
• and
• one minus the duty cycle is equal to a parameter;
• wherein the system controller is configured to keep a multiplication product of the duty cycle, the parameter and the duration of the on-time period approximately constant;
• wherein:
• the input signal changes over time along a first waveform;
• and
• the average of the current changes over time along a second waveform similar to the first waveform.

A system controller for regulating a power converter, the system controller comprising:

• a driver configured to output a drive signal to a switch to affect a current flowing through an inductive winding of a power converter, the drive signal being associated with a switching period including an on-time period and an off-time period;
• a ramp-current generator configured to receive a modulation signal and generate a ramp current based at least in part on the modulation signal;
• a ramp-signal generator configured to receive the ramp current and generate a ramping signal based at least in part on the ramp current;
• a modulation component configured to receive the ramping signal and generate the modulation signal based at least in part on the ramping signal;
• and
• a logic controller configured to receive the modulation signal and generate a control signal based at least in part on the modulation signal;
• wherein:
• the switch is closed in response to the drive signal during the on-time period;
• the switch is opened in response to the drive signal during the off-time period;
• a duty cycle is equal to a duration of the on-time period divided by a duration of the switching period;
• and
• one minus the duty cycle is equal to a parameter;
• wherein the system controller is configured to keep a multiplication product of the duty cycle, the parameter and the duration of the on-time period approximately constant;
• wherein the driver is further configured to generate the drive signal based at least in part on the control signal.

A system controller for regulating a power converter, the system controller comprising:

• a driver configured to output a drive signal to a switch to affect a current flowing through an inductive winding of a power converter, the drive signal being associated with a switching period including an on-time period and an off-time period;
• a first controller terminal configured to receive a first signal related to an input signal of the power converter;
• and
• a second controller terminal configured to receive a current sensing signal associated with the current flowing through the inductive winding;
• wherein:
• the switch is closed in response to the drive signal during the on-time period;
• the switch is opened in response to the drive signal during the off-time period;
• a duty cycle is equal to a duration of the on-time period divided by a duration of the switching period;
• and
• one minus the duty cycle is equal to a parameter;
• wherein the system controller is configured to keep a multiplication product of the duty cycle, the parameter and the duration of the on-time period approximately constant;
• wherein the switch is connected between the first controller terminal and the second controller terminal.

A system controller for regulating a power conversion system, the system controller comprising:

• a ramp-current generator configured to receive a modulation signal and generate a ramp current based at least in part on the modulation signal;
• a ramp-signal generator configured to receive the ramp current and generate a ramping signal based at least in part on the ramp current;
• a modulation component configured to receive the ramping signal and generate the modulation signal based at least in part on the ramping signal;
• and
• a driver configured to generate a drive signal based on at least information associated with the modulation signal and output the drive signal to a switch to affect a first current flowing through an inductive winding of a power converter, the drive signal being associated with a switching period including an on-time period and an off-time period;
• wherein:
• the switch is closed in response to the drive signal during the on-time period;
• the switch is opened in response to the drive signal during the off-time period;
• a duty cycle is equal to a duration of the on-time period divided by a duration of the switching period;
• and
• one minus the duty cycle is equal to a parameter;
• wherein the ramp-current generator is further configured to generate the ramp current approximately proportional in magnitude to a multiplication product of the duty cycle and the parameter.

A method for regulating a power conversion system, the method comprising:

• generating a drive signal associated with a switching period including an on-time period and an off-time period;
• and
• outputting the drive signal to a switch to affect a current flowing through an inductive component;
• wherein the outputting the drive signal to the switch to affect the current includes:
• outputting the drive signal to close the switch during the on-time period;
• and
• outputting the drive signal to open the switch during the off-time period;
• wherein:
• a duty cycle is equal to a duration of the on-time period divided by a duration of the switching period;
• and
• one minus the duty cycle is equal to a parameter;
• wherein the generating the drive signal associated with the switching period includes keeping a multiplication product of the duty cycle, the parameter and the duration of the on-time period approximately constant;
• wherein the keeping the multiplication product of the duty cycle, the parameter and the duration of the on-time period approximately constant includes keeping the multiplication product of the duty cycle, the parameter and the duration of the on-time period constant.

A method for regulating a power conversion system, the method comprising:

• receiving a modulation signal;
• generating a ramp current based at least in part on the modulation signal;
• receiving the ramp current;
• generating a ramping signal based at least in part on the ramp current;
• receiving the ramping signal;
• generating the modulation signal based at least in part on the ramping signal;
• receiving the modulation signal;
• generating a drive signal based at least in part on the modulation signal, the drive signal being associated with a switching period including an on-time period and an off-time period;
• and
• outputting the drive signal to a switch to affect a first current flowing through a primary winding of a power conversion system;
• wherein the outputting the drive signal to the switch to affect the first current includes:
• outputting the drive signal to close the switch during the on-time period;
• and
• outputting the drive signal to open the switch during the off-time period;
• wherein:
• a duty cycle is equal to a duration of the on-time period divided by a duration of the switching period;
• and
• a parameter is equal to one minus the duty cycle;
• wherein the generating the ramp current based at least in part on the modulation signal includes generating the ramp current approximately proportional in magnitude to a multiplication product of the duty cycle and the parameter.