This presentation by Sam Ben-Yaakov, titled “Back to Basics: Practical Capacitor Charging Currents,” explores the behavior of charging currents in power electronics systems using an LTspice simulation. It addresses a common scenario where a capacitor connected to a power source (like a battery) initially has no charge, leading to potentially hazardous high current spikes. To manage this, pre-charging circuits with resistors and switches are often used to control the current. The presentation delves into the effects of resistance, inductance, and capacitance in such circuits, explaining how these elements interact and influence the charging process. Using a practical RLC circuit model, the speaker demonstrates how inductance reduces peak currents, highlights power losses due to resistance, and shows the relationship between system parameters and oscillation behavior.
The key takeaway is that while inductance helps limit dangerous peak currents, it can introduce oscillations and affect resonance frequency. The simulation illustrates how varying inductance and resistance changes current peaks and power losses, providing valuable insights for designing stable circuits. However, the speaker warns that inductance at the input of an inverter in a closed-loop system may lead to instability due to negative resistance effects. This highlights the trade-offs between stability and current limitation in capacitor charging circuits, emphasizing the importance of careful system design.
For further information, check out these videos:
- Instability and oscillations of inverters’/converters’ bus capacitors: Part I
- Correction to:Instability and oscillations of inverters’/converters’ bus capacitors: Part I
Relates posts:
Video content
- Introduction to the problem
- Pre-Charge circuit
- RLC circuit description
- Key observations
- LTspice simulation
- Simulation results
- Inductance effects
- Resistance effects.
- Conclusions
- Final notes
Source: Sam Ben-Yaakov
