Inverter Controller Chip Temperament via Independent Phase Frequency
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Solution Overview
Problem
Inverters operating at low output frequencies experience significant temperature fluctuations due to alternating loads, leading to premature aging of semiconductor modules, and existing solutions either increase power losses or require costly oversizing of power semiconductors.
Innovation Solution
The inverter independently adjusts the switching frequency of each phase branch based on its own switching frequency parameter, allowing for gentle operation by minimizing temperature swings and power losses, while maintaining accurate tracking of the setpoint profile, and incorporating features like monolithic semiconductor modules and thermal coupling for efficient heat management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the inverter is operated at low output frequency, then the output current follows a sinusoidal pattern with long period, but the semiconductor chip experiences large temperature swings that accelerate aging
Solution Approach 1:
The patent applies periodic switching action within each output period to generate multiple switching cycles. By introducing a switching frequency parameter that defines multiple switching periods within one output current period, the semiconductor chip experiences more frequent but smaller temperature fluctuations instead of large swings, reducing thermal stress and aging while maintaining low output frequency operation
Solution Approach 2:
The patent dynamically adjusts the switching frequency parameter based on operating conditions. By making the number of switching cycles per output period variable rather than fixed, the system can optimize the balance between reducing temperature swings and maintaining efficient operation, thereby improving semiconductor reliability without sacrificing performance
2Reliability
If the switching frequency is increased to reduce temperature swings, then the semiconductor module aging is reduced, but the power losses increase
Solution Approach 1:
The patent changes the switching frequency parameter dynamically based on operating conditions such as output current magnitude and thermal state. By adjusting this parameter, the system finds an optimal balance point where temperature swings are sufficiently reduced to protect the semiconductor, while switching losses remain acceptable, thus resolving the contradiction between reliability and energy efficiency
3Reliability
If power semiconductors are oversized to reduce temperature swings, then the semiconductor module aging is reduced, but the cost increases significantly
Solution Approach 1:
Instead of changing the physical size of the semiconductor components, the patent changes operational parameters (switching frequency, number of switching cycles per output period) to achieve the same protective effect. This parameter-based approach reduces temperature swings and extends component lifespan without requiring expensive oversizing, thus resolving the contradiction between reliability and manufacturing cost
4Reliability
If the switching frequency is adjusted independently per phase branch, then the temperature control is optimized, but the control system complexity increases
Solution Approach 1:
The patent segments the control system by allowing independent switching frequency parameter adjustment for each phase branch. This segmentation enables optimized temperature control for each phase based on its specific loading and thermal conditions, while the modular nature of the control architecture minimizes the added complexity, resolving the contradiction between reliability and system complexity
Data Source
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AI summary
The invention relates to an inverter (28) having two DC voltage inputs (34, 36) and at least two phase branches (38). Each phase branch (38) comprises an AC voltage output (40), a switching bridge (42') for alternately galvanically coupling the AC voltage output (40) with the DC voltage inputs (34, 36), and a modulator (46) for controlling the switching bridge (42') by means of a pulse signal (Su, Sv, Sw). The object of the invention is to enable gentle operation of the switching bridges (42') in the inverter (28). According to the invention, each modulator (46) is designed to change the switching frequency of its pulse signal (Su, Sv, Sw) independently of any other modulator (46) during operation of the inverter (28) according to a switching frequency parameter (1/Tu, 1/Tv, 1/Tw).