Parallel Converter Drive-Pulse Control for Low-Current Distortion
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Solution Overview
Problem
Existing power conversion apparatuses for permanent-magnet synchronous motors in hybrid vehicles face challenges in reducing distortion in output currents due to increased complexity and noise from multiple parallel converters, especially when command current values are low, leading to harmonic current distortion and electromagnetic compatibility issues.
Innovation Solution
A power conversion apparatus with first to xth converters connected in parallel, featuring a pulse generator that selects and generates multiple drive-pulse trains to drive a variable number of converters, and a variable determiner to adjust the multiply-driven number, ensuring sufficient drive pulse width and reducing distortion in output currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple converters are connected in parallel to reduce output current distortion, then the distortion reduction effect is improved, but the device complexity and noise increase
Solution Approach 1:
The patent divides the parallel converter system into multiple independently controllable converter units, each capable of being selectively driven. By segmenting the control strategy into individual converter control, the system achieves distortion reduction without proportionally increasing overall control complexity, as each segment can be managed separately through the pulse generator's selective drive capability.
Solution Approach 2:
The patent implements dynamic control of the parallel converter system by using a variable determiner that adjusts the multiply-driven number n based on operating conditions. This dynamic adaptation allows the system to optimize the number of actively driven converters according to command current values and operational requirements, thereby managing complexity dynamically rather than statically.
2Manufacturing precision
If multiple converters are driven in parallel at low command current values, then the distortion reduction is improved, but the control complexity and noise increase
Solution Approach 1:
The variable determiner dynamically adjusts the multiply-driven number n based on command current values, enabling the control system to adapt to low current conditions without excessive complexity. At low command current values, the system optimally selects the number of converters to drive, balancing distortion reduction with manageable control complexity through condition-based dynamic adjustment.
Solution Approach 2:
The patent changes the operational parameter of the multiply-driven number n based on command current values. By varying this parameter according to operating conditions, the system achieves effective distortion reduction at low current values while maintaining reasonable control complexity through parameter adaptation rather than fixed complex control.
3Manufacturing precision
If the multiply-driven number is increased to reduce distortion, then the distortion reduction effect is improved, but the drive pulse width may become insufficient
Solution Approach 1:
The pulse generator implements dynamic control of the multiply-driven number n, allowing the system to adjust the number of driven converters based on real-time conditions. This dynamic adjustment ensures that when n is increased for distortion reduction, the drive pulse width remains sufficient by coordinating the timing and distribution of drive pulses across the selected converters.
Solution Approach 2:
The patent uses periodic drive pulse trains with controlled timing to drive the selected converters. By implementing periodic action with appropriate pulse width and timing intervals, the system can drive multiple converters effectively while maintaining sufficient pulse width for each, preventing the pulse width from becoming insufficient when the multiply-driven number is increased.
Data Source
AI summary
In a power conversion apparatus, first to xth converters are connected in parallel to each other. A control unit outputs, based on command information related to an output of the power conversion apparatus, control information. A pulse generator selects, based on the control information, a number n of converters from the first to xth converters, n being an integer more than or equal to 2 and smaller than x. The number n is defined as a multiply-driven number n. The pulse generator generates, based on the control information, at least one multiple drive-pulse train that comprises n drive pulses for multiply driving the n selected converters. A variable determiner changes the multiply-driven number n.