DC/DC Converter Phase Shift Control for Capacitor Voltage Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional DC/DC converters face challenges in accurately determining the direction of power transmission between the low-voltage and high-voltage sides due to ripple components in reactor current, leading to incorrect voltage control of the charge/discharge capacitor, which can result in overvoltage and reliability issues.
Innovation Solution
A DC/DC converter design that includes a control device generating gate signals for switching elements, with a duty command calculation unit and a phase shift duty command calculation unit, shifting the phases of gate signals for the second and third switching elements relative to the first and fourth switching elements, ensuring stable voltage control of the charge/discharge capacitor regardless of power transmission direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ON time of switching elements is adjusted based on detected reactor current to control charge/discharge capacitor voltage, then voltage control is achieved, but incorrect power transmission direction determination occurs due to ripple components in reactor current
Solution Approach 1:
The control device determines the power transmission direction in advance by detecting the polarity of reactor current before using this information to control the charge/discharge capacitor voltage. This preliminary determination of power flow direction allows the system to properly adjust switching element ON times without being misled by current ripple components, ensuring reliable voltage control.
2Measurement precision
If the reactor current is averaged to determine power transmission direction, then ripple components are reduced, but detection delay occurs making it impossible to respond to rapid direction changes
Solution Approach 1:
Instead of completely averaging the reactor current which would smooth out all variations including rapid direction changes, the control device uses the detected reactor current polarity directly to determine power transmission direction. This partial action approach maintains responsiveness to rapid direction changes while still providing sufficient information for accurate control decisions.
3Reliability
If conventional voltage control methods are used for the charge/discharge capacitor, then voltage regulation is attempted, but overvoltage occurs due to incorrect polarity control from misidentified power direction
Solution Approach 1:
The control device continuously monitors reactor current polarity to determine power transmission direction and uses this feedback information to adjust the ON times of switching elements appropriately. This feedback mechanism ensures that voltage control actions are always aligned with the actual power flow direction, preventing overvoltage conditions caused by incorrect polarity control.
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 stabilizes voltage control of the charge/discharge capacitor by adjusting current flow into and out of the capacitor, maintaining a predetermined polarity relationship and enhancing reliability by preventing overvoltage and incorrect power direction determination.
Implementation Method 1
One of conventional DC/DC converters controls the amount of energy accumulated into a reactor and the amount of energy released from the reactor
Implementation Method 2
there is known a technique of reducing voltage applied to the reactor by using charging and discharging of a capacitor
Data Source
AI summary
A DC/DC converter includes: duty command calculation units for calculating duty command values for first, second, third, and fourth switching elements on the basis of difference voltage between a high-voltage-side voltage command value and a high-voltage-side voltage detection value; and a phase shift duty command calculation unit for calculating a phase shift duty command value corresponding to a phase difference between gate signals for the first and fourth switching elements and gate signals for the second and third switching elements, on the basis of difference voltage between a voltage target value and a charge voltage detection value of a charge/discharge capacitor, wherein gate signals for driving the first, second, third, fourth switching elements are generated on the basis of the duty command values and the phase shift duty command value.