Converter Control Device for Vehicle Resonance Suppression
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Solution Overview
Problem
Conventional converter circuits struggle to suppress output voltage variations caused by motor torque fluctuations, leading to resonance issues due to the coincidence of torque variation frequencies with the resonance frequency of the LC resonance circuit, which results in increased drive voltage variation and costs associated with large capacitance requirements.
Innovation Solution
A converter control device with a basic command value calculation section, variation state detection section, and correction value calculation section is implemented to generate a control signal that corrects the basic command value, thereby suppressing drive voltage variations by adjusting the duty cycle of the switching elements in the converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large capacitance capacitor is used to suppress drive voltage variation, then the drive voltage stability is improved, but the device cost and size increase
Solution Approach 1:
The patent changes the control parameters of the switching elements (duty cycle, switching timing) to dynamically adjust the converter output and suppress drive voltage variation, eliminating the need for large capacitance capacitors
Solution Approach 2:
The patent implements feedback control by detecting the drive voltage variation and adjusting the switching element control based on the detected variation, thereby stabilizing the drive voltage without requiring large capacitance
2Productivity
If the resonance frequency of the LC resonance circuit coincides with the torque variation frequency, then the system operates efficiently, but the drive voltage variation is magnified due to resonance
Solution Approach 1:
The patent applies preliminary anti-action by detecting the drive voltage variation before it is magnified by resonance and adjusting the switching element control in advance to counteract the resonant effect, thereby suppressing the harmful voltage variation
Solution Approach 2:
The patent makes the control system dynamic by continuously adjusting the switching element parameters based on real-time detection of drive voltage variation, allowing the system to adapt to resonant conditions and suppress voltage variation effectively
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 solution effectively reduces drive voltage variations by detecting and correcting resonance-induced fluctuations, improving system stability and reducing the need for large capacitors, thus lowering costs and enhancing overall system performance.
Implementation Method 1
the resonance frequency of the booster circuit is about 205 Hz as calculated using the following expression (1). (1⁄2)×[1/{2π√(500μ×300μ)}]≈205 (1) The resonance frequency falls in the variation range (0 to 2 kHz) of the torque variation frequency of the motor described above as an example. Hence, during a vehicle travel, the torque variation frequency and the resonance frequency of the LC resonance circuit often coincide with each other. When the torque variation frequency and the resonance frequency happen to coincide with each other, the variation width of the drive voltage outputted from the booster circuit is magnified by the resonance.
Data Source
AI summary
A boost control section for controlling a converter includes a PI control section and a resonance suppression section. The PI control section calculates a basic command value based on a deviation between a drive voltage generated by the converter and a target voltage to equalize the drive voltage and the target voltage. The resonance suppression section calculates, based on the state of variation of the drive voltage, a correction value for correcting the basic command value to suppress the variation. The basic command value is corrected by adding the correction value. First and second drive pulses corresponding to the corrected command value are outputted to the converter.