Active Capacitive Coupler for Efficient High Voltage Step-Down
Traditional capacitive dropper circuits typically utilize a passive shunt element to perform voltage regulation at the DC output. This element carries the full dropper capacitor current at all times, and as a result, dissipates power when no or little load is applied to the circuit. This wastes energy during light-load periods of operation, and additionally limits the power capacity of larger dropper circuits to that which is reasonably able to be dissipated by a passive regulator element such as a pass transistor or Zener diode.
Researchers at Arizona State University have developed a new capacitive coupler that creates usable voltage for small electronics by efficiently harvesting and converting energy from high-voltage power lines.
The active capacitive coupler utilizes an actively-controlled current-steering circuit in series with a current-limiting capacitor in order to transform a higher and potentially variable AC voltage to a lower regulated DC voltage. The topology intrinsically limits the maximum voltage across all switching elements and diodes to that of the DC output voltage, and as such may be used to transform very high AC voltages (limited by the dropper capacitor rating only) to low DC voltage.
• Telecommunication power lines
• Electrical line maintenance
• Recharge stations for electric vehicles and drones
• Consumer electronics
Benefits and Advantages
• Employs a switched-mode regulator that dissipates minimal power in the regulating element
• Allows operation at greater efficiency than an equivalent passive shunt-regulated capacitive coupler over most (especially lighter) load ranges
• Versatile design can accommodate various types of electronics
• Compact, minimalist form simplifies field implementation