Battery charging apparatus and control method
A battery charging apparatus includes a first converter coupled between an input voltage bus and a battery, and a second converter coupled between the input voltage bus and the battery, wherein switches of the first converter and switches of the second converter are integrated in a same semiconductor chip, and wherein the first converter and the second converter are configured to be coupled to a controller, the controller being configured to generate gate drive signals for configuring the first converter and the second converter during a charging process of the battery such that a load current distribution between the first converter and the second converter is controlled based on an input current limit of the battery charging apparatus.
1 . A battery charging apparatus comprising:
a first converter coupled between an input voltage bus and a battery; and
a second converter coupled between the input voltage bus and the battery, wherein switches of the first converter and switches of the second converter are integrated in a same semiconductor chip, and wherein the first converter and the second converter are configured to be coupled to a controller, the controller being configured to generate gate drive signals for configuring the first converter and the second converter during a charging process of the battery such that a load current distribution between the first converter and the second converter is controlled based on a total input current limit of the battery charging apparatus.
2 . The battery charging apparatus of claim 1 , wherein:
the first converter is a dual-phase switched capacitor converter; and
the second converter is a buck converter.
3 . The battery charging apparatus of claim 2 , wherein the dual-phase switched capacitor converter comprises:
a first switch, a second switch, a third switch and a fourth switch connected in series between the input voltage bus and ground;
a first flying capacitor connected between a common node of the first switch and the second switch, and a common node of the third switch and the fourth switch;
a fifth switch, a sixth switch, a seventh switch and an eighth switch connected in series between the input voltage bus and ground; and
a second flying capacitor connected between a common node of the fifth switch and the sixth switch, and a common node of the seventh switch and the eighth switch, and wherein a common node of the second switch and the third switch is connected to a common node of the sixth switch and the seventh switch, and further connected to an output of the dual-phase switched capacitor converter.
4 . The battery charging apparatus of claim 2 , wherein the buck converter comprises:
a high-side switch and a low-side switch connected in series between the input voltage bus and ground; and
an inductor connected between a common node of the high-side switch and the low-side switch, and an output bus of the buck converter.
5 . The battery charging apparatus of claim 4 , further comprising:
an isolation switch connected between the output bus of the buck converter and the battery.
6 . The battery charging apparatus of claim 1 , wherein:
the second converter is configured to operate in a power saving mode in response to an increase of a current flowing through the first converter.
7 . The battery charging apparatus of claim 6 , wherein:
the second converter is configured to leave the power saving mode once the first converter is shut down.
8 . The battery charging apparatus of claim 1 , wherein:
the second converter is configured to operate in a forced PWM mode to provide a sink current in response to an increase of a load transient caused by the first converter.
9 . A method comprising:
prior to activating a charge pump converter, applying an input current limit control mechanism to a step-down converter, wherein the charge pump converter and the step-down converter are connected in parallel between an input voltage bus and a battery;
after activating the charge pump converter, reducing a current flowing through the step-down converter so that a sum of a current flowing through the charge pump converter and the current flowing through the step-down converter is equal to a total input current limit at the input voltage bus;
configuring the charge pump converter and the step-down converter to provide power to the battery simultaneously, wherein the step-down converter is configured to operate in a pulse skip mode; and
after the charge pump converter is shut down, configuring the step-down converter to leave the pulse skip mode and operate with a current equal to the total input current limit.
10 . The method of claim 9 , further comprising:
reducing the current flowing through the step-down converter until the step-down converter enters into the pulse skip mode.
11 . The method of claim 9 , further comprising:
detecting a current flowing into the input voltage bus; and
applying the input current limit control mechanism to the step-down converter based on a detected current indicative of the current flowing into the input voltage bus.
12 . The method of claim 9 , further comprising:
packaging switches of the charge pump converter and switches of the step-down converter into one single semiconductor chip; and
detecting a current flowing into the one single semiconductor chip through a current detecting circuit in the one single semiconductor chip.
13 . The method of claim 9 , further comprising:
after the charge pump converter is shut down, increasing the current flowing through the step-down converter until the current flowing through the step-down converter reaches the input total current limit.
14 . The method of claim 9 , wherein:
coupling the input voltage bus to a receiver coil of a wireless power transfer system.
15 . The method of claim 9 , wherein the charge pump converter comprises:
a first switch, a second switch, a third switch and a fourth switch connected in series between the input voltage bus and ground;
a first flying capacitor connected between a common node of the first switch and the second switch, and a common node of the third switch and the fourth switch;
a fifth switch, a sixth switch, a seventh switch and an eighth switch connected in series between the input voltage bus and ground; and
a second flying capacitor connected between a common node of the fifth switch and the sixth switch, and a common node of the seventh switch and the eighth switch, and wherein a common node of the second switch and the third switch is connected to a common node of the sixth switch and the seventh switch, and further connected to an output of the charge pump converter.
16 . The method of claim 9 , wherein the step-down converter comprises:
a high-side switch and a low-side switch connected in series between the input voltage bus and ground; and
an inductor connected between a common node of the high-side switch and the low-side switch, and an output bus of the step-down converter.
17 . A controller comprising:
a plurality of gate drivers configured to generate a plurality of gate drive signals for driving switches of a charge pump converter and switches of a step-down converter, wherein:
the charge pump converter and the step-down converter are connected in parallel between an input voltage bus and a battery; and
a load current distribution between the charge pump converter and the step-down converter is controlled based on a total input current limit at the input voltage bus.
18 . The controller of claim 17 , wherein the controller is configured such that:
prior to activating the charge pump converter, apply an input current limit control mechanism to the step-down converter;
after activating the charge pump converter, reduce a current flowing through the step-down converter so that a sum of a current flowing through the charge pump converter and the current flowing through the step-down converter is equal to the total input current limit;
configure the charge pump converter and the step-down converter to provide power to the battery simultaneously, wherein the step-down converter is configured to operate in a pulse skip mode; and
after the charge pump converter is shut down, configure the step-down converter to leave the pulse skip mode and operate with a current equal to the total input current limit.
19 . The controller of claim 17 , wherein:
the charge pump converter comprises:
a first switch, a second switch, a third switch and a fourth switch connected in series between the input voltage bus and ground;
a first flying capacitor connected between a common node of the first switch and the second switch, and a common node of the third switch and the fourth switch;
a fifth switch, a sixth switch, a seventh switch and an eighth switch connected in series between the input voltage bus and ground; and
a second flying capacitor connected between a common node of the fifth switch and the sixth switch, and a common node of the seventh switch and the eighth switch, and wherein a common node of the second switch and the third switch is connected to a common node of the sixth switch and the seventh switch, and further connected to an output of the charge pump converter; and
the step-down converter comprises:
a high-side switch and a low-side switch connected in series between the input voltage bus and ground; and
an inductor connected between a common node of the high-side switch and the low-side switch, and an output bus of the step-down converter.
20 . The controller of claim 17 , wherein:
switches of the charge pump converter and switches of the step-down converter are packaged in a single semiconductor chip; and
the input voltage bus is coupled to a receiver coil of a wireless power transfer system.