Variable Impedance Capacitor Control for Power Supply Volume Reduction
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Solution Overview
Problem
AC-to-DC power supplies require large and costly capacitors to store energy across a wide range of input voltages, leading to increased physical size and cost due to the need for high capacitance values and voltage ratings, which is inefficient and impractical for compact electronic equipment.
Innovation Solution
The implementation of a variable impedance element and a driver circuit that dynamically control the engagement and disengagement of capacitances based on the rectified voltage, allowing a combination of high and low voltage capacitors to optimize energy storage while minimizing physical volume and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If high capacitance values and high voltage ratings are used to ensure operation across wide AC input voltage range, then reliability and adaptability are improved, but device volume and cost increase significantly
Solution Approach 1:
The bulk capacitance is divided into multiple separate capacitor components (first bulk capacitor component and second bulk capacitor component) with different voltage ratings. This segmentation allows each capacitor to be optimized for specific voltage ranges, reducing the total volume required compared to using a single high-voltage capacitor designed for the maximum voltage range.
Solution Approach 2:
The patent implements dynamic switching between different capacitor configurations based on the detected AC input voltage level. A controller selectively engages or disengages capacitor components during normal operation and during holdup periods, optimizing the capacitance value for each operating condition. This dynamic adaptation reduces the need for oversized capacitors that would be required to handle all conditions simultaneously.
2Reliability
If high capacitance values are used to maintain minimum input voltage for DC-to-DC converter, then operational reliability is improved, but device volume and cost increase
Solution Approach 1:
The controller dynamically adjusts the effective capacitance by selectively engaging or disengaging capacitor components based on operating conditions. During normal operation, the full capacitance is available to maintain minimum input voltage. During holdup periods after AC input removal, the controller manages the discharge of capacitors to extend operational time, reducing the required capacitance value for achieving the same reliability.
Solution Approach 2:
The patent changes the effective capacitance parameter dynamically based on operating conditions. By detecting AC input voltage levels and operational state (normal operation vs. holdup period), the system adjusts which capacitor components are active, optimizing the capacitance value for each condition and reducing the overall volume required compared to using maximum capacitance continuously.
3Reliability
If high voltage rating capacitors are used to withstand maximum AC input voltage, then reliability is improved, but cost increases significantly
Solution Approach 1:
The bulk capacitance is segmented into multiple capacitor components with different voltage ratings (e.g., first component rated for lower voltage, second component rated for higher voltage). This allows the system to use cheaper, lower-voltage-rated capacitors for the majority of the capacitance requirement, while using higher-voltage-rated capacitors only for the portion needed to handle maximum voltage conditions, significantly reducing overall cost compared to using high-voltage capacitors for the entire capacitance value.
Solution Approach 2:
The system dynamically changes which capacitor components are active based on the AC input voltage level. When AC voltage is below maximum, lower-voltage-rated capacitors suffice. When AC voltage approaches maximum, the controller engages additional high-voltage-rated capacitors. This parameter change strategy allows the use of cheaper capacitors for most operating conditions, reducing overall manufacturing cost while maintaining reliability across the full voltage range.
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 approach reduces the physical volume and cost of capacitors required for energy storage, ensuring efficient operation across a range of input voltages while maintaining the necessary holdup time and output voltage stability.
Implementation Method 1
The bulk capacitance receives the rectified input current, using it to store energy in the form of a voltage on one or more capacitors
Implementation Method 2
A variable impedance element and a driver circuit are provided in an energy storage circuit of an AC-to-DC power supply
Data Source
AI summary
A driver circuit included in a power supply having a rectifier coupled to a single phase AC input voltage is disclosed. An example driver circuit includes a drive signal generator to generate a drive signal to be coupled to a variable impedance element. A voltage sensor is coupled to the drive signal generator and is to be coupled to sense a voltage across a high voltage capacitance. The driver circuit is to be coupled to control the variable impedance element in response to the voltage sensor. A low voltage capacitance is allowed to receive current from the input if the sensed voltage is less than a second threshold value. The low voltage capacitance is prevented from receiving current from the input if the sensed voltage is greater than a first threshold value.