| CPC H02M 3/01 (2021.05) [H02M 1/0058 (2021.05); H02M 3/07 (2013.01)] | 20 Claims |
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1. A control module, for a resonant switched-capacitor converter comprising first, second, third, and fourth switches connected in cascade, wherein the first and second switches form a first inner node, the second and third switches form an output node configured to be coupled to a load and an output capacitor, and the third and fourth switches form a second inner node, the converter configured to receive an input voltage and generate an output voltage on the output node, and comprising a resonant series circuit, which is coupled to the first and second inner nodes and includes an inductor and a first capacitor, the control module comprising:
a controller stage configured to control the first, second, third, and fourth switches so that the converter operates alternatively in:
a first phase, in which the first and third switches are closed, and the second and fourth switches are open, so that an inductor current that flows through the inductor is coupled to the load;
a second phase, in which the second and third switches are closed, and the first and fourth switches are open, so that the inductor current is decoupled from the load;
a third phase, in which the second and fourth switches are closed, and the first and third switches are open, so that the inductor current is coupled to the load; and
a fourth phase, in which the first and fourth switches are closed, and the second and third switches are open, so that the inductor current is decoupled from the load;
an input stage configured to generate a first control signal indicating a control quantity;
a delay stage configured to receive the first control signal and to generate a duration signal indicating a time quantity that depends on the control quantity according to a first function that is monotonically increasing or decreasing;
a zero-crossing detection circuit coupled to the inductor and configured to generate a current signal indicating zero crossings of the inductor current;
wherein the control quantity is fixed, or variable and depends on a difference between a reference quantity and a feedback quantity that depends on the output voltage;
wherein the input stage is further configured, when the control quantity is variable, to clamp the control quantity to a control threshold in response to the control quantity reaching the control threshold, wherein the control threshold is a lower bound for the control quantity when the first function is monotonically increasing, or is an upper bound for the control quantity when the first function is monotonically decreasing;
wherein the controller stage is further configured to:
receive the current signal and the duration signal; and
operate in a normal mode, in which the controller stage controls the first, second, third, and fourth switches to carry out a phase sequence by iterating pulses, each respective pulse including a respective first phase, a respective second phase, a respective third phase, and a respective fourth phase, the respective first, second, third and fourth phases having respective timings that depend on the zero crossings of the inductor current and on the time quantity, so that a duration of each pulse rises as the time quantity rises and the converter generates on the output node an average output current directed to the load and the output capacitor that depends on the time quantity according to a monotonically increasing second function, wherein the average output current is prevented from dropping below a minimum load current, which is a function of the control quantity when the control quantity is fixed, and of the control threshold, when the control quantity is variable, wherein the output voltage thereby tends to rise when the load drains a load current that is lower than the minimum load current;
a comparison stage configured to generate a second control signal indicating time instants in which the output voltage reaches an upper voltage threshold and time instants in which the output voltage drops to a lower voltage threshold; and
wherein the controller stage is further configured to:
receive the second control signal;
when the second control signal indicates that the output voltage has reached the upper voltage threshold, to switch from the normal mode to a pulse-skipping mode, in which the controller stage suspends execution of the phase sequence, thereby causing the output voltage to drop; and
resume the execution of the phase sequence after the second control signal indicates that the output voltage has dropped to the lower voltage threshold.
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