Booster Circuit Control for Unbalanced AC Sources
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Solution Overview
Problem
In power supply apparatuses for air conditioning and heat source systems, the existing booster circuit control mechanisms are prone to frequent boosting start and stop cycles when the AC source is unbalanced, leading to increased switching losses and reduced component lifetime due to the close setting of first and second set values for boosting.
Innovation Solution
A controller is implemented to adjust the set values for boosting start and stop based on the balance state of the AC source, setting a lower value when unbalanced to prevent immediate reactivation of the booster circuit, thereby reducing switching losses and extending component lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the first set value for boosting stop is set close to the second set value for boosting start, then switching loss of the booster circuit is reduced, but frequent repetitions of boosting start and stop occur when the AC source is in an unbalanced state, adversely affecting component lifetime
Solution Approach 1:
The patent applies dynamics by making the set values dynamic rather than fixed. The controller adjusts the first and second set values based on the balance state of the AC source. When the AC source is unbalanced, the controller sets the first set value lower than the second set value by a larger margin, preventing frequent boosting cycles. When balanced, the values are set closer together to minimize switching loss. This dynamic adjustment resolves the contradiction between reducing switching loss and preventing component fatigue.
Solution Approach 2:
The patent changes the parameters (set values) based on operating conditions. Specifically, the controller monitors the balance state of the AC source and adjusts the threshold values for boosting start and stop accordingly. When unbalance is detected, the hysteresis width between the first and second set values is increased, which prevents immediate reactivation of boosting and reduces switching frequency, thereby protecting components while still managing energy loss.
2Reliability
If the hysteresis width between first set value and second set value is increased to prevent frequent boosting cycles, then component lifetime is extended, but switching loss increases due to prolonged boosting period
Solution Approach 1:
The patent makes the hysteresis width dynamic rather than fixed. The controller adjusts the difference between the first and second set values based on the AC source balance state. When the AC source is unbalanced, a larger hysteresis width is applied to prevent frequent boosting cycles and protect components. When the AC source is balanced, the hysteresis width is reduced to minimize the boosting period and reduce switching loss. This dynamic approach resolves the contradiction between component protection and energy efficiency.
Solution Approach 2:
The patent changes the hysteresis width parameter based on operating conditions. The controller monitors AC source balance and adjusts the threshold values accordingly. When unbalance is detected, the first set value is set significantly lower than the second set value, creating a larger hysteresis width that prevents immediate reactivation. When balanced, the values are closer together, reducing the hysteresis width and minimizing energy loss while still providing sufficient protection.
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
The solution effectively reduces switching losses and prevents frequent boosting cycles, thereby enhancing the lifespan of electronic components in the booster circuit by adjusting set values according to AC source balance states.
Implementation Method 1
a rectifier circuit configured to rectify voltages of an AC source
Implementation Method 2
booster circuit including a series circuit of a reactor and first switch element configured to boost an output voltage of the rectifier circuit by turning on/off of the first switch element
Data Source
AI summary
According to one embodiment, when an effective value of an input current flowing into a booster circuit rises to a value greater than or equal to a second set value, boosting of the booster circuit is started and, after the start, when the effective value lowers to a value lower than a first set value lower than the second set value, boosting of the booster circuit is stopped. Then, if the three-phase AC source is in an unbalanced state, the first set value is set to a value lower than usual.