These highly specialized transformers are designed to enhance and control characteristics that are normally minimized. CVTs require highly controlled leakage inductance (the inductance that prevents any primary voltage from transferring to the secondary) to isolate the secondary from the primary. The leakage inductance is electrically connected to a capacitor that forms a resonant tank circuit causing the secondary portion of the magnetic core to saturate. Saturation, something to be avoided in other transformer designs, is exploited to force a maximum limit on the secondary voltage.
The pros and cons of CVTs with this capability are:
- Good output regulation with no active circuitry
- High reliability
- Excellent primary to secondary isolation
- Improved power factor on the primary even when the secondary is rectified and filtered
- Excellent tolerance to continued short-circuit on the secondary
- Can be audibly noisy
- Large size relative to power output
- Requires separate resonating capacitor
- Does not tolerate surge loads
- Lower efficiency due to more core material and saturating part of the core
Electronetics designs CVT transformers for a wide variety of applications with regulation profiles as tight as ±3% with an input voltage variation as much as ±15%. Contact us today.