Inverter Controller Two-Phase Modulation Dwell Balance
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Solution Overview
Problem
Conventional two-phase modulation systems for inverter controllers experience dwell period unbalance and phase unbalance in switching, leading to impaired driving characteristics and unnecessary pulsation in load current or output torque when the carrier wave frequency is lowered to reduce switching loss.
Innovation Solution
An inverter controller that sets the carrier wave frequency to an integral multiple of the modulation wave frequency in two-phase modulation mode, ensuring balanced dwell periods and preventing phase unbalance during switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the carrier wave frequency is lowered to decrease switching loss, then the switching loss is reduced and cooler downsizing is enabled, but the modulation accuracy is degraded and noise level increases
Solution Approach 1:
The patent applies segmentation by dividing the three-phase switching control into two independent phase controls with one phase dwelled. This two-phase modulation approach segments the switching operations to reduce the total number of switchings and lower switching loss while maintaining acceptable modulation performance
Solution Approach 2:
The patent changes the carrier wave frequency parameter to be an integral multiple of the modulation wave frequency. This parameter adjustment optimizes the switching pattern to reduce unnecessary switchings while maintaining modulation accuracy, resolving the contradiction between lowering switching frequency and maintaining modulation precision
2Loss of energy
If the carrier wave frequency is lowered to decrease switching loss, then the switching loss is reduced, but the noise level becomes greater
Solution Approach 1:
The patent adjusts the carrier wave frequency to be an integral multiple of the modulation wave frequency, which optimizes the switching pattern. This parameter change reduces the number of unnecessary switchings, thereby lowering switching loss while simultaneously suppressing noise generation by eliminating irregular switching patterns
3Loss of energy
If the carrier wave frequency is lowered to decrease switching loss, then the switching loss is reduced, but the modulation accuracy is degraded
Solution Approach 1:
The patent sets the carrier wave frequency as an integral multiple of the modulation wave frequency, which creates optimized switching patterns. This parameter relationship ensures that switching operations are synchronized with the modulation waveform, maintaining modulation accuracy while reducing the total number of switchings and associated losses
4Loss of energy
If two-phase modulation is used to reduce switching loss, then the switching loss decreases to approximately 2/3, but dwell period unbalance and phase unbalance occur
Solution Approach 1:
The patent changes the carrier wave frequency parameter to be an integral multiple of the modulation wave frequency. This parameter adjustment synchronizes the carrier wave with the modulation wave, ensuring balanced dwell periods across phases and eliminating phase unbalance while maintaining the reduced switching loss benefits of two-phase modulation
Data Source
AI summary
A PWM operation unit includes a modulation-mode selecting unit selecting a two-phase modulation mode signal and a carrier-wave-synchronous-mode select command, a modulation-wave generating unit generating a modulation wave in response to the two-phase modulation mode signal, a carrier-wave generating unit generating a carrier wave in response to the carrier-wave-synchronous-mode select command, and a comparing unit comparing the modulation wave with the carrier wave. In a two-phase modulation mode, the PWM operation unit controls the carrier-wave generating unit such that a carrier wave frequency is set to an integral multiple of a modulation wave frequency.