DC to DC Converter Dynamic PWM Frequency Control for Overshoot Mitigation
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Solution Overview
Problem
Conventional DC to DC converters experience significant overshoot issues when the output current changes rapidly, leading to transient DC output voltages that exceed the steady-state voltage, which can negatively impact the performance of computer system components.
Innovation Solution
A control method is introduced where the operating frequency of the PWM signal is dynamically adjusted based on the DC output voltage, switching to a higher frequency when the output voltage exceeds a threshold, thereby increasing the switching speed of the power transistors to mitigate overshoot. This involves a control circuit that monitors the output voltage and adjusts the PWM signal frequency from a first frequency to a second, higher frequency when the output voltage is above a predetermined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the output current changes rapidly, then the response speed of the DC to DC converter is improved, but the overshoot voltage increases
Solution Approach 1:
The patent applies dynamics by making the PWM frequency adjustable rather than fixed. The control circuit dynamically changes the PWM frequency based on the operating mode: using a first frequency in normal mode and a second frequency (higher than the first) in overshoot mode. This dynamic adjustment allows the system to optimize between response speed and overshoot control depending on the operating conditions.
Solution Approach 2:
The patent changes the PWM frequency parameter to control overshoot. By detecting when overshoot occurs and switching to a higher PWM frequency, the system modifies this key parameter to reduce the overshoot voltage. The control circuit monitors the output voltage and adjusts the frequency parameter accordingly, transitioning between two distinct frequency states to manage overshoot.
2Object-generated harmful factors
If the PWM frequency is increased to reduce overshoot, then the overshoot voltage is reduced, but the switching losses increase
Solution Approach 1:
The system dynamically adjusts PWM frequency based on operating conditions rather than maintaining a high frequency continuously. The control circuit switches between a first frequency (normal operation) and a second frequency (overshoot correction), allowing the system to minimize switching losses during normal operation while only increasing frequency when overshoot occurs.
Solution Approach 2:
The patent changes the PWM frequency parameter selectively - using a lower first frequency during normal operation to minimize switching losses, and switching to a higher second frequency only when overshoot is detected. This conditional parameter change optimizes the trade-off between overshoot reduction and energy efficiency.
Data Source
AI summary
A DC to DC converter includes a control circuit, a gate driver circuit, and a power stage circuit. The control circuit receives and compares a DC output voltage. When the DC output voltage lower than a first threshold voltage, a PWM signal with a first frequency is outputted, and when the DC output voltage higher than the first threshold voltage, the PWM signal with a second frequency is outputted. The second frequency is higher than the first frequency. The gate driver circuit receives the PWM signal and converts the PWM signal to a first driving signal and a second driving signal. The power stage circuit converts a DC input voltage to the DC output voltage according to the first driving signal and the second driving signal.