Inverter Engine Generator Bridge Circuit Voltage Control
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Solution Overview
Problem
Inverter type engine generators require a separate DC booster circuit due to the use of a three-phase bridge circuit for rectification and motor driving, leading to size, weight, and cost issues.
Innovation Solution
A three-phase rectifying bridge circuit with duty-controllable switching elements and thyristors, along with a processor and memory for controlling the elements to achieve step-up/down functionality and motor starting, allowing a single circuit to perform rectification, boosting, and motor driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a three-phase bridge circuit is used for both rectification and motor driving, then device complexity is reduced, but voltage adjustment capability is lost requiring additional DC booster circuit
Solution Approach 1:
The three-phase bridge circuit is designed to perform multiple functions: rectification during power generation mode and motor driving during starting mode. The same circuit elements (switching elements and diodes) are used for both rectifying AC from the alternator and driving the rotary motor, eliminating the need for separate circuits and reducing overall device complexity while maintaining adaptability through mode switching
Solution Approach 2:
The bridge circuit operates dynamically in different modes controlled by the processor. During power generation, it functions as a rectifier converting AC to DC. During motor starting, it switches to motor drive mode where the same elements are controlled differently to supply three-phase AC to the motor. This dynamic reconfiguration allows one circuit to serve multiple purposes without requiring additional voltage adjustment circuits
2Adaptability or versatility
If separate DC booster circuit is added for voltage adjustment, then voltage control capability is improved, but device size and weight increase
Solution Approach 1:
The voltage control and motor driving functions are merged into the same three-phase bridge circuit. The switching elements (FETs/IGBTs) and diodes in the bridge circuit are controlled by the processor to achieve both rectification with voltage regulation and motor driving. By combining these functions in one circuit rather than using separate DC booster circuit, the overall device size and weight are reduced while maintaining voltage control capability
3Adaptability or versatility
If separate DC booster circuit is added for voltage adjustment, then voltage control capability is improved, but device cost increases
Solution Approach 1:
The three-phase bridge circuit is designed as a universal circuit that performs both rectification with voltage control and motor driving functions. The same power semiconductor elements (switching elements and diodes) and control processor are used for both operations, eliminating the need for additional DC booster circuit components. This reduces manufacturing cost by reducing the total number of components while maintaining full voltage control capability through intelligent control of the bridge circuit elements
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
Enables a compact, lightweight, and cost-effective solution for inverter type engine generators by integrating rectification, step-up/down, and motor starting functions into a single three-phase bridge circuit, improving efficiency and reducing size and weight.
Implementation Method 1
an alternator 12, which has three-phase windings 12a, 12b, 12c, is driven by a rotary motor 10 to generate power
Implementation Method 2
a converter 14, which converts a three-phase alternating current output from the alternator 12 into a direct current
Data Source
AI summary
An inverter type engine generator includes an alternator operable as a motor for starting an engine; a converter composed of a three-phase rectifying bridge circuit, converting three-phase alternating current output from the alternator into direct current, and operatable as a motor driver for driving the alternator when power is supplied from a power source; and a processor and a memory. 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 from duty-controllable switching elements and thyristors connected in parallel therewith, and lower elements are configured from duty-controllable switching elements having diodes. The processor and the memory perform turning off the lower elements and controlling the duty of the thyristors while turning off the upper elements so that an output voltage of the three-phase rectifying bridge circuit is reduced, when a detected terminal voltage of the converter exceeds the target voltage.