Power Converter Switching Control for Accurate Semiconductor Switchover
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Solution Overview
Problem
Existing power converter systems for electrical axle drives in motor vehicles face challenges in achieving accurate and efficient switchover between different types of semiconductors with minimal errors in voltage-time integral, particularly during torque-free emergency operations of synchronous machines.
Innovation Solution
The method involves using discontinuous pulse-width modulation to actuate switching elements in a power converter system, where two types of switching elements are operated in parallel with temporally separate actuation, adjusting parameters such as pulse-width, pulse duration, and pulse interval to minimize current errors and ensure accurate switchover, and equalizing load between high-side and low-side switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If discontinuous pulse-width modulation is used for switchover between different types of semiconductors, then switchover accuracy is improved, but device complexity increases
Solution Approach 1:
The control system dynamically adjusts the pulse-width modulation parameters based on real-time current flux measurements. The controller continuously monitors the current flux and dynamically modifies the pulse width, pulse duration, and pulse interval of the PWM signals to achieve accurate switchover between different semiconductor types while adapting to changing operating conditions.
Solution Approach 2:
The system employs feedback control by continuously measuring the current flux through sensors and using this information to adjust the PWM signal parameters. The controller compares the measured current flux with reference values and modifies the pulse characteristics accordingly, ensuring accurate switchover timing and minimizing current errors during the transition between different semiconductor types.
2Productivity
If parallel operation of different switching elements is implemented, then efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by assigning different operational characteristics to different switching elements based on their specific capabilities and the local operating conditions. Each switching element type (e.g., IGBT, MOSFET, SiC) is optimized for specific current flux ranges, and the control system activates the appropriate element type for each local operating condition, thereby maximizing overall system efficiency while managing precision requirements.
Solution Approach 2:
The system changes operational parameters dynamically by adjusting the pulse width, pulse duration, and pulse interval of PWM signals based on the current flux level and the specific switching element being controlled. This parameter adaptation allows the system to optimize the performance of each switching element type for its operating range, achieving high efficiency while compensating for manufacturing variations through dynamic parameter adjustment.
3Object-generated harmful factors
If temporally separate actuation of switching elements is used, then current errors are minimized, but loss of time increases
Solution Approach 1:
The control system performs preliminary action by preparing the next switching element for activation in advance. Before completely deactivating one switching element, the system pre-charges the gate capacitance of the next element and positions the PWM signal parameters for the upcoming transition. This preliminary preparation reduces the actual switchover time while maintaining the benefits of temporally separate actuation for minimizing current errors.
Solution Approach 2:
The system rushes through the critical switchover transition by using discontinuous pulse-width modulation with optimized pulse timing. The PWM controller delivers concentrated control pulses that quickly establish the desired switching state, minimizing the duration of the transition period. This approach allows the system to complete the switchover rapidly while still maintaining temporal separation to avoid current errors during the transition.
Data Source
AI summary
A method for operating at least one switching device of a power converter includes actuating a first switching element of the switching device by a first pulse-width modulation signal when the current flux in the switching device lies below a predefined threshold value, or actuating a second switching element of the switching device by a second pulse-width modulation signal when a current flux in the switching device exceeds the predefined threshold value. At least one parameter of the first pulse-width modulation signal and/or of the second pulse-width modulation signal is adjusted according to the time point of achievement of the predefined threshold value.