Inverter Boost Converter Phase Shifted Switching Control
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Solution Overview
Problem
The existing in-vehicle power conversion systems using boost converters and inverters face issues with surge voltage increases due to switching state changes, leading to increased torque ripple and deteriorated ride comfort, as described in PTL 1, where the frequency of switching state changes becomes high, causing distortion in output voltage and torque ripple.
Innovation Solution
A power conversion system that includes a boost converter and an inverter, controlled by a device generating switching signals based on comparisons of duty command values and triangular wave carriers, where the frequency of the second triangular wave carrier for the inverter is equal to the first, and its phase is 180 degrees different, to synchronize switching operations and reduce surge voltage without increasing torque ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the switching control signal input to the inverter is corrected such that change timing of switching state of the boost converter and change timing of switching state of the inverter are not overlapped, then the surge voltage is reduced, but the frequency of prohibiting output of change command becomes high, causing distortion of output voltage and increased torque ripple
Solution Approach 1:
The patent applies periodic action by synchronizing the switching operations of the boost converter and inverter at the same frequency. The control device generates switching signals such that both converters operate periodically with coordinated timing, preventing surge voltage while maintaining regular switching patterns that avoid torque ripple. This is achieved by making the switching frequency of the inverter equal to the switching frequency of the boost converter and coordinating their switching phases.
2Speed
If the switching frequency is increased to improve power conversion efficiency, then the response speed improves, but the surge voltage increases and torque ripple worsens
Solution Approach 1:
The patent maintains a fixed switching frequency for both the boost converter and inverter, creating periodic switching patterns. By coordinating the switching phases of both converters to operate at the same frequency with synchronized timing, the system achieves fast response without generating surge voltage. The periodic nature of the switching ensures that voltage changes are predictable and controlled.
Solution Approach 2:
The control device performs preliminary coordination of switching signals before actual switching occurs. By pre-synchronizing the switching phases of the boost converter and inverter, the system prepares the power conversion path in advance to handle voltage transitions smoothly, preventing surge voltage even at high switching frequencies.
Data Source
AI summary
A surge according to a change of a switching state can be reduced without increasing a torque ripple of a motor. A first switching signal to control switching of a boost converter is generated on the basis of a comparison of a first duty command value and a first triangular wave carrier of the boost converter. A second switching signal to control switching of an inverter is generated on the basis of a comparison of a second duty command value and a second triangular wave carrier of the inverter. In addition, the second triangular wave carrier is generated such that a frequency of the second triangular wave carrier becomes equal to a frequency of the first triangular wave carrier and a phase of the second triangular wave carrier is different from a phase of the first triangular wave carrier by 180 degrees.