Wind Generator Converter Segmentation for Reliability
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Solution Overview
Problem
Conventional full power back-to-back converter systems for wind power generation face inefficiencies due to high switching frequencies, increased component costs, and reduced reliability, especially as wind power generation demands higher voltages and larger power levels, with existing solutions struggling to handle these demands effectively.
Innovation Solution
A generator system with a main converter for power production and an auxiliary converter for control functions, utilizing a diode full-bridge rectifier for the main converter and a PWM full-bridge converter for the auxiliary, allowing for optimized design for high power levels and reduced current ratings in control windings, thereby simplifying and cost-reducing the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PWM switching occurs at high frequency (2.5 kHz) to control current harmonics and torque ripples, then generator control dynamics are improved, but power losses and heat increase, reducing efficiency and converter lifetime
Solution Approach 1:
The converter is divided into multiple independent power units (modules) connected in parallel. Each module operates at a lower switching frequency, avoiding the high switching losses and heat generation associated with high-frequency PWM operation of a single large converter. This segmentation allows the system to achieve the required power level while maintaining lower individual switching frequencies for each module.
Solution Approach 2:
The switching frequency parameter is changed from a high uniform frequency across the entire converter to lower individual frequencies for each power unit. By operating each module at its optimal lower frequency and coordinating their operation, the system achieves effective control while reducing overall switching losses and improving converter lifetime.
2Power
If multiple power units are arranged in parallel to handle high power levels, then the required power capacity is achieved, but current sharing between modules becomes difficult to control, requiring special techniques like pulse insertion or dropping
Solution Approach 1:
A control system with feedback mechanisms monitors and adjusts the operation of each parallel power unit to maintain balanced current sharing. The control system detects current imbalances and applies corrective actions to individual modules, eliminating the need for complex predetermined techniques like pulse insertion or dropping while achieving optimal current distribution.
3Reliability
If more converter modules are used to create current/power margins, then system reliability is improved, but component cost and system complexity increase
Solution Approach 1:
Each power unit module is designed to be universal and multi-functional, capable of operating independently to provide both power conversion and control functions. This modularity allows the system to achieve required reliability margins through parallel redundancy while keeping each module relatively simple, avoiding the need for overly complex individual components.
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 system achieves reliable high-power generation while being relatively cheap and simple in construction, with reduced switching losses and extended component lifetime, and lower costs due to lower current ratings in control windings, improving efficiency and reliability.
Implementation Method 1
the rotor is adapted to induce electrical voltage in the first set of windings and in the second set of windings when the rotor is rotated relative to the stator
Implementation Method 2
the first converter being adapted to convert alternating voltage in the first set of windings into an output DC voltage
Implementation Method 3
the second converter being adapted to generate control voltages and/or control currents in the second set of windings
Data Source
Figure 1
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Figure 3
AI summary
There is described a generator for producing electric power, the generator comprising (a) a generator unit (210, 410', 510, 610) comprising a stator (313) and a rotatably supported rotor, wherein the stator comprises a first set of windings (211, 411', 511, 611) and a second set of windings (212, 412, 512, 612), and wherein the rotor is adapted to induce electrical voltage in the first set of windings and in the second set of windings when the rotor is rotated relative to the stator, the generator further comprising (b) a first converter (220, 421, 522, 622) coupled to the first set of windings, the first converter being adapted to convert alternating voltage in the first set of windings into an output DC voltage, (c) a DC output coupled to the first converter to receive the output DC voltage, and (d) a second converter (230, 430, 532, 632) coupled to the second set of windings and to the DC output, the second converter being adapted to generate control voltages and/or control currents in the second set of windings.