PFM Voltage Converter With Input-Adaptive MOS On-Time Control
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Solution Overview
Problem
Known pulse frequency modulation (PFM) type switched-mode converters face inefficiencies in power conversion due to dependencies on the input voltage, leading to increased electric power consumption and variability in output regulation.
Innovation Solution
A DC/DC voltage converter design that maintains a MOS transistor in the on state for a time period proportional to the inverse of the potential difference between the power supply and output voltages, using a control circuit with ramp generators and comparators to regulate the converter's operating cycles, ensuring the converter operates efficiently regardless of input voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PFM-type switched-mode converters are used for power conversion, then the converter can operate with variable frequency, but the power consumption increases and output regulation becomes variable due to dependency on input voltage
Solution Approach 1:
The patent changes the control parameter from fixed frequency to variable duty cycle, where the MOS transistor remains in the on state for a time period proportional to the inverse of the potential difference between input and output voltages. This parameter adaptation allows the converter to maintain efficient operation across varying input voltage conditions while regulating output voltage consistently.
Solution Approach 2:
The control circuit implements feedback by monitoring the output voltage and adjusting the MOS transistor on-time accordingly. The time period is dynamically set based on the potential difference between power supply and output voltages, creating a closed-loop control system that regulates power consumption and output voltage simultaneously.
2Adaptability or versatility
If PFM-type switched-mode converters are used for power conversion, then the converter can operate with variable frequency, but output voltage regulation becomes variable due to dependency on input voltage
Solution Approach 1:
The patent adapts the duty cycle parameter dynamically by setting the MOS transistor on-time proportional to the inverse of the potential difference. This ensures that even though the operating frequency varies, the output voltage regulation remains consistent and reliable across different input voltage conditions.
Solution Approach 2:
The control system dynamically adjusts the MOS transistor on-time based on real-time voltage conditions. The time period is not fixed but is continuously adapted to maintain proper output voltage regulation despite variations in input voltage and operating frequency.
3Device complexity
If the MOS transistor on-time is fixed in PFM converters, then the control is simple, but the converter efficiency decreases and output regulation becomes input-voltage dependent
Solution Approach 1:
The patent implements dynamic parameter adjustment where the MOS transistor on-time is set proportional to the inverse of the potential difference between input and output voltages. This adaptive approach optimizes conversion efficiency by matching the duty cycle to the actual voltage conversion requirements, rather than using a fixed time period.
Solution Approach 2:
The control circuit preliminarily determines the appropriate on-time duration based on the measured potential difference before activating the MOS transistor. This pre-calculation ensures that the transistor remains on for the optimal duration needed for efficient power conversion, avoiding both excessive conduction losses and insufficient power transfer.
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
This design minimizes electric power consumption and maintains output voltage regulation independently of input voltage fluctuations, ensuring efficient power delivery to loads while optimizing converter performance.
Implementation Method 1
a current source having a first terminal connected to the first rail and having a second terminal connected to the third node, the current source being configured to deliver a current having a value proportional to the potential difference
Implementation Method 2
a capacitor connected between the second rail and a third node configured to deliver the potential ramp
Implementation Method 3
an operational amplifier having a first input, preferably inverting, configured to receive the output potential, having a second input, preferably non-inverting, connected to the fourth node, and having an output connected to a control terminal of the third transistor and to a control terminal of the fourth transistor
Implementation Method 4
a first MOS transistor connected between a first rail configured to receive a power supply potential and a first node; and an inductance connected between the first node and a second node configured to deliver an output potential
Implementation Method 5
an inductance connected between the first node and a second node configured to deliver an output potential
Data Source
AI summary
In an embodiment, a voltage converter includes: a first transistor coupled between a first rail configured to receive a supply voltage and a first node; and an inductance coupled between the first node and a second node configured to deliver an output voltage, wherein, at each operating cycle of the converter, the first transistor is maintained in the on state for a first time period proportional to the inverse of a voltage difference between the supply voltage and the output voltage.