Hysteretic Mode Controller for Capacitor Voltage Divider Efficiency
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Solution Overview
Problem
Conventional voltage converters, such as buck converters, suffer from inefficiencies like diode reverse recovery and inductor power loss, while capacitive voltage dividers face challenges in maximizing efficiency within electronic circuits.
Innovation Solution
A capacitor voltage divider with a hysteretic mode controller using a pulse width modulation (PWM) signal and a hysteretic mode controller that includes an amplifier, gain circuit, and hysteretic comparator circuit to control the switching frequency based on load current, maintaining efficiency by adjusting the switching frequency with increasing load current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional buck converter is used to reduce voltage level, then voltage conversion is achieved, but efficiency deteriorates due to diode reverse recovery and inductor power loss
Solution Approach 1:
The patent replaces the conventional buck converter topology with a capacitor voltage divider topology, substituting inductors and diodes with capacitors and switches. This eliminates the mechanical/physical limitations of inductor core losses and diode reverse recovery effects, achieving superior efficiency while maintaining voltage conversion functionality.
Solution Approach 2:
The patent changes the fundamental operating parameters by using capacitive elements instead of inductive elements for voltage conversion. The capacitor voltage divider uses different physical principles (capacitive charging/discharging) compared to conventional inductive switching, fundamentally altering the energy transfer mechanism to reduce losses.
2Loss of energy
If fixed frequency PWM control is used in capacitor voltage divider, then control simplicity is maintained, but efficiency deteriorates under varying load conditions
Solution Approach 1:
The patent implements a hysteretic control mechanism that continuously monitors the output voltage and adjusts the PWM duty cycle accordingly. When the output voltage drops below a lower threshold, the PWM signal activates to charge the capacitors; when it exceeds an upper threshold, the PWM signal deactivates. This feedback loop automatically adapts to varying load conditions, maintaining high efficiency without requiring complex external control circuits.
Solution Approach 2:
The patent transitions from fixed-frequency PWM control to dynamic frequency control through hysteretic mode operation. The switching frequency automatically adjusts based on load demands and voltage conditions, allowing the system to optimize efficiency across different operating points while maintaining relatively simple control circuitry through inherent hysteretic behavior.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The capacitor voltage divider with hysteretic mode control maintains high efficiency across varying load currents and input voltages, achieving efficiency levels above 95% even at low input voltages and high load currents, outperforming conventional converters.
Implementation Method 1
a hysteretic mode controller that includes an amplifier, gain circuit, and hysteretic comparator circuit to control the switching frequency based on load current
Data Source
AI summary
A hysteretic mode controller for controlling a capacitor voltage divider which has a flying capacitor. In one embodiment, the hysteretic mode controller includes an amplifier, a gain circuit and a hysteretic comparator circuit. The amplifier has an input for coupling to the flying capacitor and an output providing a fly voltage. The gain circuit has an input for receiving the input voltage and an output coupled to a reference node providing a reference voltage. The hysteretic comparator circuit has a first input coupled to the output of the amplifier, a second input receiving the reference voltage, and an output for providing a PWM signal to control the capacitor voltage divider. The fly voltage is compared to voltage limits of a hysteretic voltage window for switching the PWM signal. The switching frequency is increased with higher load current to maintain high efficiency.