Inverter Engine Generator Duty-Controllable Bridge Circuit
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Solution Overview
Problem
Existing inverter type engine generators have limitations due to their single step-down function, requiring higher alternator voltage at each rotation speed, which restricts their characteristics, structure, and withstand voltage, and necessitate additional DC step-up/down circuits.
Innovation Solution
A three-phase bridge circuit with duty-controllable diode and switching elements, including thyristors and MOSFETs, is used to convert three-phase AC to DC, enabling both step-up and step-down operations within a single circuit, allowing for flexible voltage control through an electronic control unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a mixed bridge circuit of thyristor and diode is used for rectification with voltage control by firing angle, then the configuration achieves step-down function without DC step-up/down circuit, but the configuration causes significant limitations in characteristics, structure, and withstand voltage
Solution Approach 1:
The patent applies dynamic control by making all six bridge circuit elements duty-controllable switching elements with anti-parallel diodes, allowing the rectifier to dynamically switch between step-up and step-down operation modes. This dynamic configurability resolves the contradiction by enabling the circuit to adapt its characteristics and withstand voltage requirements based on operating conditions, rather than being fixed in a single step-down configuration.
Solution Approach 2:
The patent implements universality by designing a bridge circuit where all elements are duty-controllable switching elements capable of performing multiple functions: rectification, step-up conversion, and step-down conversion. This multi-functional design eliminates the need for separate DC step-up/down circuits and resolves the contradiction by providing both step-up and step-down capabilities within a single universal circuit structure.
2Adaptability or versatility
If upper elements are configured from duty-controllable diode elements and lower elements from duty-controllable switching elements having diodes, then both step-up and step-down functions are achieved in a single three-phase bridge circuit, but the device complexity increases
Solution Approach 1:
The patent applies merging by combining the rectifier circuit and DC step-up/down circuits into a single integrated three-phase bridge circuit. All six bridge elements are configured as duty-controllable switching elements with anti-parallel diodes, merging multiple functions (rectification, step-up, step-down) into one unified structure. This resolves the contradiction by achieving functional integration while managing complexity through unified design.
Solution Approach 2:
The patent implements universality by designing all bridge elements as duty-controllable switching elements that can perform multiple operations: rectification during normal operation, step-up conversion during low rotation speeds, and step-down conversion during high rotation speeds. This multi-functional universal design resolves the contradiction by providing both step-up and step-down capabilities within the same circuit structure.
3Device complexity
If a single three-phase bridge circuit performs both rectification and step-up/down functions, then additional DC step-up/down circuits are eliminated, but the control complexity of the bridge elements increases
Solution Approach 1:
The patent applies feedback control by using a control unit that monitors the alternator's rotation speed and automatically adjusts the duty ratios of the bridge elements accordingly. During low rotation speeds, the control unit increases duty ratio for step-up operation; during high rotation speeds, it decreases duty ratio for step-down operation. This automated feedback control resolves the contradiction by managing control complexity through intelligent, condition-based adjustment rather than manual configuration.
Solution Approach 2:
The patent implements dynamic control by enabling the control unit to continuously adjust the duty ratios of all six bridge elements based on real-time rotation speed feedback. This dynamic control strategy automatically transitions the circuit between rectification, step-up, and step-down modes as needed, resolving the contradiction by automating the control process rather than requiring fixed, complex manual configuration.
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 configuration allows for efficient power generation across a wide range of rotation speeds, reducing the alternator's winding specifications, lowering idle rotation speed, and enhancing noise and fuel efficiency, while eliminating the need for additional step-up/down circuits, thus providing a more versatile and compact generator.
Implementation Method 1
an alternator (power generation unit) which has three-phase windings and is driven by a rotary motor to generate power
Implementation Method 2
a converter control unit configured to control driving of the elements of the three-phase rectifying bridge circuit so that a direct-current terminal voltage output from the converter becomes a target voltage
Data Source
AI summary
An inverter type engine generator includes an alternator; and a converter composed of the a three-phase rectifying bridge circuit including an upper and lower three sets of elements, and converting three-phase alternating current output from the alternator into direct current. The upper and lower three sets of elements of the three-phase rectifying bridge circuit of the converter are configured such that upper elements are configured at least from duty-controllable diode elements, and lower elements are configured at least from duty-controllable switching elements having diodes.