Charger having fast transient response and control method thereof

Patent metadata

Field	Value
Publication number	US-11088560-B2
Application number	US-201816049753-A
Country	US
Kind code	B2
Filing date	Jul 30, 2018
Priority date	Apr 3, 2018
Publication date	Aug 10, 2021
Grant date	Aug 10, 2021

Abstract

A charger having a fast transient response and a control method thereof are provided, which decide how to quickly respond to a requirement of a load by determining whether an input current reference signal indicating an input current is larger than or equal to a maximum safe current of a transformer. Therefore, the charger and the control method realize the fast transient response without having to control switching between a boost circuit and a buck circuit. Meanwhile, the charger and the control method thereof can be prevented from being damaged by an excessive input current and can stabilize an output voltage of the load more quickly.

First claim

What is claimed is:

1. A charger having a fast transient response, the charger comprising:
a transformer configured to supply an input current;
a current detector coupled to the transformer and configured to detect the input current to generate an input current reference signal indicating the input current;
a power stage circuit having one terminal coupled to the transformer and a load and another terminal coupled to an energy storage element;
a feedback compensation circuit coupled between the current detector and the power stage circuit, the power stage circuit is configured to detect a charging current and a charging voltage of the energy storage element, and the feedback compensation circuit is configured to generate an amplified error signal according to the charging current, the charging voltage and the input current reference signal;
a ramp circuit coupled to the current detector and configured to generate a ramp signal; and
a control circuit coupled between the ramp circuit, the feedback compensation circuit and the power stage circuit, and the control circuit is configured to control the power stage circuit according to the ramp signal and the amplified error signal;
wherein when the input current reference signal is larger than or equal to a maximum safe current of the transformer, the ramp circuit raises the ramp signal or the feedback compensation circuit reduces the amplified error signal, and the control circuit accordingly controls the power stage circuit to stop the input current charging the energy storage element and starts the energy storage element to charge the load through the power stage circuit, and when the input current reference signal is smaller than the maximum safe current, the ramp signal and the amplified error signal are not adjusted by the ramp circuit and the feedback compensation circuit respectively, and the control circuit accordingly controls the power stage circuit to transmit the input current to the load and the energy storage element.

2. The charger having the fast transient response of claim 1 , wherein the ramp circuit includes:
a ramp generator configured to generate the ramp signal; and
a ramp adjuster coupled between the ramp generator and the current detector and having the maximum safe current, and the ramp adjuster is configured to determine whether the input current reference signal is larger than or equal to the maximum safe current;
wherein when the input current reference signal is larger than or equal to the maximum safe current, the ramp adjuster raises the ramp signal;
wherein when the input current reference signal is smaller than the maximum safe current, the ramp signal is not raised by the ramp adjuster.

3. The charger having the fast transient response of claim 2 , wherein the ramp adjuster includes:
a variable current source;
a comparator having a positive terminal and a negative terminal, the positive terminal receiving the input current reference signal and the negative terminal receiving the maximum safe current generated by a current generator, and the comparator being configured to control the variable current source to generate a current signal according to the input current reference signal and the maximum safe current; and
an adder coupled to the variable current source and the ramp generator and configured to add up the ramp signal and the current signal;
wherein when the input current reference signal is larger than or equal to the maximum safe current, the comparator controls the variable current source to generate the current signal indicating a positive value;
wherein when the input current reference signal is smaller than the maximum safe current, the comparator controls the variable current source to generate the current signal indicating 0.

4. The charger having the fast transient response of claim 2 , wherein the ramp adjuster includes:
a variable voltage source;
a comparator having a positive terminal and a negative terminal, the positive terminal receiving the input current reference signal and the negative terminal receiving the maximum safe current generated by a current generator, and the comparator being configured to control the variable voltage source to generate a voltage signal according to the input current reference signal and the maximum safe current; and
an adder coupled to the variable voltage source and the ramp generator, and the adder is configured to add up the ramp signal and the voltage signal;
wherein when the input current reference signal is larger than or equal to the maximum safe current, the comparator controls the variable voltage source to generate the voltage signal indicating a positive value;
wherein when the input current reference signal is smaller than the maximum safe current, the comparator controls the variable voltage source to generate the voltage signal indicating 0.

5. The charger having the fast transient response of claim 1 , wherein the feedback compensation circuit includes:
an error amplifier configured to generate the amplified error signal; and
an amplified error adjuster coupled between the error amplifier and the current detector, the amplified error adjuster has the maximum safe current and is configured to determine whether the input current reference signal is larger than or equal to the maximum safe current;
wherein when the input current reference signal is larger than or equal to the maximum safe current, the amplified error regulator reduces the amplified error signal;
wherein when the input current reference signal is smaller than the maximum safe current, the amplified error signal is not reduced by the amplified error regulator.

6. The charger having the fast transient response of claim 5 , wherein the amplified error adjuster includes:
a variable voltage source;
a comparator having a positive terminal and a negative terminal, the positive terminal receiving the input current reference signal and the negative terminal receiving the maximum safe current generated by a current generator, and the comparator being configured to control the variable current source to generate a current signal according to the input current reference signal and the maximum safe current; and
an adder coupled to the variable current source and the error amplifier and configured to add up the amplified error signal and the current signal;
wherein when the input current reference signal is larger than or equal to the maximum safe current, the comparator is configured to control the variable current source to generate the current signal indicating a negative value;
wherein when the input current reference signal is larger than or equal to the maximum safe current, the comparator is configured to control the variable current source to generate the current signal indicating 0.

7. The charger having the fast transient response of claim 5 , wherein the amplified error adjuster includes:
a variable voltage source;
a comparator having a positive terminal and a negative terminal, the positive terminal receiving the input current reference signal and the negative terminal receiving the maximum safe current generated by a current generator, and the comparator being configured to control the variable voltage source to generate a voltage signal according to the input current reference signal and the maximum safe current; and
an adder coupled to the variable voltage source and the error amplifier and configured to add up the amplified error signal and the voltage signal;
wherein when the input current reference signal is larger than or equal to the maximum safe current, the comparator controls the variable voltage source to generate the voltage signal indicating a negative value;
wherein when the input current reference signal is smaller

Assignees

• Anpec Electronics Corp

Inventors

• Hsu Chun-Kai
• Chen Chih-Ning

Classifications

• H02J7/933

  the cycle being controlled or terminated in response to electric parameters · CPC title

• H02M1/08 Primary

  Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters · CPC title

• H02J7/02

  for charging batteries from AC mains by converters · CPC title

• H02M3/158

  including plural semiconductor devices as final control devices for a single load · CPC title

• H03K4/48

  using as active elements semiconductor devices (H03K4/787 - H03K4/84 take precedence) · CPC title