Matrix AC/AC Converter PWM Control Reduces Switching Losses
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Solution Overview
Problem
Existing matrix direct AC/AC converters are inefficient due to high energy losses, primarily conduction and switching losses, which make them costly and not easily producible.
Innovation Solution
A matrix direct AC/AC converter with a control device that generates PWM signals to minimize switching losses by optimizing the connection of input and output phases, using a combination of IGBTs and diodes, and an FPGA-based control system to process input and output signals, reducing unnecessary switching and energy wastage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional PWM control is used to generate output voltages, then the converter can achieve arbitrary voltage amplitude and frequency control, but switching losses increase significantly
Solution Approach 1:
The patent applies periodic action by using a triangular carrier signal that periodically intersects with sinusoidal reference signals to generate PWM control pulses. This periodic modulation enables the switching devices to operate in a controlled manner, achieving voltage and frequency control while managing switching losses through optimized switching patterns.
Solution Approach 2:
The patent changes parameters by dynamically adjusting the amplitude and frequency of the output voltages through PWM modulation. By varying the duty cycle of the PWM signals based on the intersection points of carrier and reference signals, the converter achieves arbitrary voltage amplitude and frequency control while optimizing switching operations.
2Ease of operation
If frequent switching of IGBTs is performed to control output voltages, then the converter can regulate voltage amplitude, but switching losses increase proportionally to switching frequency and voltage amplitude squared
Solution Approach 1:
The patent employs feedback by continuously monitoring the output voltages and comparing them with reference signals. The PWM control device adjusts the switching signals based on the error between actual and desired voltages, enabling precise voltage amplitude regulation while optimizing switching frequency to minimize losses.
Solution Approach 2:
The patent applies dynamics by making the switching frequency and duty cycle variable rather than fixed. The PWM control dynamically adjusts switching parameters based on instantaneous voltage requirements, allowing flexible voltage regulation while reducing unnecessary switching events that would increase losses.
3Adaptability or versatility
If nine electronic two-way switching devices are used to connect all input phases with all output phases, then the converter can achieve matrix direct AC/AC conversion, but conduction losses increase due to voltage drop across switching devices
Solution Approach 1:
The patent applies preliminary action by pre-configuring the switching devices in a matrix arrangement with anti-series IGBT pairs and parallel diodes. This preliminary setup enables the converter to handle both voltage polarity directions without requiring additional switching operations, reducing conduction losses by eliminating unnecessary voltage drops during current flow.
4Manufacturing precision
If PWM control signals are generated to obtain sinusoidal output voltages and currents, then the converter can achieve high quality power conversion, but device complexity increases due to control circuit requirements
Solution Approach 1:
The patent applies segmentation by dividing the control function into modular components: a PWM control device that generates basic modulation signals and a microprocessor that provides higher-level control and coordination. This segmentation allows sinusoidal waveform generation to be handled by the dedicated PWM circuit while reducing the complexity burden on the microprocessor.
Solution Approach 2:
The patent uses an intermediary approach by introducing a dedicated PWM control device as a mediator between the microprocessor and the switching devices. This intermediary handles the complex PWM signal generation and switching coordination, freeing the microprocessor from detailed timing control and reducing overall system complexity.
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 significantly reduces energy losses by minimizing switching events, resulting in a more efficient and cost-effective converter with reduced production complexity.
Implementation Method 1
switching between the conductive state ('ON') and the resistive state ('OFF') of the IGBT
Implementation Method 2
Conduction losses are due to the voltage drop across the electronic switching devices
Implementation Method 3
Switching losses are due to switching between the conductive state ('ON') and the resistive state ('OFF') of the IGBT and are substantially proportional to the output current of the IGBT, to the frequency of the PWM control signal, and to the square of the voltage amplitude corresponding to each PWM switching
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Matrix direct AC/AC converter having a plurality of electronic two-way switching devices (6) arranged so as to matrix-connect the input phases (2) to the output phases (4), and a control device (7) provided with voltage and current measuring means (8, 9) for obtaining measured values (VEM, ILM) of the input voltage (VE) of the converter and of the load current (IL) of the converter and configured for processing the measured voltage values (VEM) so as to obtain a first signal (VEmax), a second signal (VEmid), and a third signal (VEmin), which represent the maximum values, the intermediate values, and the minimum values, respectively, of the phases of the input voltage (VE), for generating a common-mode voltage (VCM) as a function of a reference voltage (VREF) for the output (4), of the measured values (VEM, ILM), and of the first, second, and third signals, and for combining the reference voltage (VREF) with the common-mode voltage (VCM) and the first, second, and third signals in such a way as to obtain a plurality of pulse-width modulated control signals (PWM), each of which is designed to control a respective two-way switch (6).