Boosting Circuit Controller for Power Supply Apparatus
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Solution Overview
Problem
The existing power supply apparatuses for air conditioning systems experience power loss due to voltage drops across diodes in the boosting circuit, and reverse recovery currents can lead to excessive surge voltages that may damage diode elements, especially during changes in load or compressor speed.
Innovation Solution
A power supply apparatus with a controller that switches the boosting circuit from boosting mode to non-boosting mode when the reactor current falls below a set value, using a configuration of a reactor, switch elements, and diodes to minimize power loss and prevent reverse recovery currents, and optionally incorporating a surge voltage absorption capacitor to protect the diode elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a second switch element is connected in parallel with the backflow prevention diode to reduce power loss, then power loss is reduced, but reverse recovery current causes excessive surge voltage that may damage diode elements
Solution Approach 1:
The patent changes the operational parameters by detecting reactor current magnitude and switching between two different circuit configurations: using the second switch element for power loss reduction when current is high, and switching to the diode-only configuration when current is low to avoid reverse recovery issues. This dynamic parameter-based switching resolves the contradiction between power efficiency and voltage safety.
Solution Approach 2:
The patent implements dynamic switching between two operational modes based on real-time reactor current detection. The controller dynamically selects which circuit path to use (boosting mode with second switch element or non-boosting mode with diode only) according to load conditions, making the system adaptable to prevent surge voltage while maintaining power efficiency when appropriate.
2Loss of energy
If the second switch element is turned on to reduce diode conduction time, then power loss is reduced, but negative reactor current flows when reactor current is near zero, causing reverse recovery current in diode elements
Solution Approach 1:
The patent employs feedback control by continuously detecting the reactor current magnitude and using this information to control the switching of the second switch element. When detection indicates reactor current is near zero, the controller prohibits turning on the second switch element, thereby preventing the reverse recovery current condition while still allowing power loss reduction when current is sufficiently high.
Solution Approach 2:
The patent takes preliminary protective action by detecting low reactor current conditions and preemptively prohibiting the activation of the second switch element before reverse recovery current can occur. This advance prevention based on current level detection ensures diode element reliability is maintained while still permitting efficient operation during high current conditions.
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 solution reduces power loss and prevents diode element damage by minimizing the duration of forward current through diodes and absorbing surge voltages, thereby enhancing the efficiency and reliability of the power supply apparatus.
Implementation Method 1
the rate of change with time (di/dt) of the negative reactor current −Ia abruptly changes from a negative value to a positive value. At this time, a large counter-electromotive force is generated in the reactor, and an excessive surge voltage resulting from the counter-electromotive force is created across the both ends of the reactor
Implementation Method 2
Normally, although a diode element does not make a current flow in the reverse direction, when a reverse voltage is applied to the diode element through which a current has so far been made to flow in the forward direction, a reverse current (called a reverse recovery current) flows through the diode element
Data Source
AI summary
According to one embodiment, the controller configured to, when an operation of the boosting circuit is in the boosting mode, and if an instantaneous value Ia of a current flowing through the reactor lowers to a value smaller than or equal to a set value Ias, switch the operation of the boosting circuit from the boosting mode to the non-boosting mode.