Inverter Controller Surge Voltage Avoidance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power converters face challenges in managing surge voltages during simultaneous switching of multiple switches, leading to potential switch breakage, and current control precision is compromised by methods that either increase component cost or switch loss.
Innovation Solution
The inverter controller adjusts switch opening/closing timings based on PWM modulation ratio instructions to avoid simultaneous switching of switches in different phases, using a surge voltage superimposition avoiding unit that generates appropriate gate signals to prevent surge voltage superimposition, thereby maintaining output voltage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If switches are changed over at the same time to improve productivity, then switching speed increases, but surge voltage is generated causing switch breakage
Solution Approach 1:
The control device determines switching timing in advance and adjusts the timing of at least one phase to avoid coincidence with other phases. By pre-calculating and preemptively adjusting switching schedules before the surge voltage issue occurs, the system maintains high switching speed while preventing switch breakage through proactive timing coordination.
2Reliability
If capacitor is connected in parallel with switches to reduce surge voltage, then switch protection is improved, but device complexity and component cost increase
Solution Approach 1:
The patent replaces the passive hardware solution (capacitor connection) with an active control solution (timing adjustment algorithm). The control device uses computational logic to determine and adjust switching timings, substituting the need for additional protective components with intelligent timing coordination that prevents surge voltage generation at its source.
Solution Approach 2:
The invention extracts and addresses the root cause of surge voltage (simultaneous switching coincidence) rather than treating the symptom with additional components. By removing the problematic simultaneous switching condition through timing adjustment, the system eliminates the need for surge voltage suppression capacitors and their associated complexity.
3Reliability
If switch operation speed is delayed to avoid surge voltage, then switch protection is improved, but current control precision deteriorates
Solution Approach 1:
The control device dynamically adjusts switching timing parameters based on real-time operational conditions. Instead of uniformly delaying all switch operations, the system selectively modifies timing parameters for specific phases and switching events, maintaining current control precision by adapting timing adjustments to the actual electrical state and load conditions.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
According to one embodiment, an inverter controller includes a current controller (10) which calculates and output PWM modulation ratio instructions of a first phase and a second phase, such that an inverter outputs a predetermined current; a switching timing arithmetic unit (221) which calculates timings at which switches of the respective phases are opened and closed; a simultaneous switching avoiding unit (220) which determines whether a first switching timing for changing over the switch of the first phase and a second switching timing for changing over the switch of the second phase coincide or not, and to generate, upon determining that the first switching timing and the second switching timing coincide, triangular-wave carriers of the first phase and the second phase by making different waveforms of the triangular-wave carriers; and a switch opening/closing timing generator (224) which calculates a timing for opening/closing the switch.