A Voltage Doubling Variable Frequency Drive (VFD) is a type of VFD that increases the output voltage beyond the input voltage level, typically used in applications where a higher voltage motor needs to be powered from a lower voltage, single or three phase supply.
How It Works:
- Rectifier – AC to DC:
- The VFD first converts the incoming AC power (single or three-phase) into DC using a rectifier.
- In a standard VFD, the DC bus voltage is approximately 1.414 times the AC line voltage (due to the rectification process).
- Voltage Doubling Circuit:
- A voltage doubling circuit, increases the DC bus voltage to approximately twice the rectified DC voltage.
- This step allows a lower input voltage (208 – 230 V) to generate a higher DC voltage (650 – 720 V DC), which can then be used to produce a higher AC output.
- Inverter – DC to AC
- The high DC voltage is then converted back into three-phase AC using three IGBTs creating a PWM waveform.
- The output frequency and voltage (v/f) are then controlled to match the motor’s requirements.
Applications:
- Powering 460 V motors using a 230 V input (common in industrial settings).
- Retrofitting older motors that require higher voltage without replacing the power supply.
- Long motor lead lengths.
Advantages
Eliminates the need for a step-up transformer.
Allows the use of existing lower-voltage infrastructure.
Significant savings on wire costs, as 460 V is half the current of 230 V.
Phase Technologies has developed and patented unique lines of voltage doubling, phase-converting VFDs. Their products are made in the USA and can convert 208V/230V/240V single-phase or three-phase input to 460V three-phase output, eliminating the need for additional transformers. These VFDs are specifically designed for pumping applications and offer features like easy-to-use interfaces and significant installation cost savings.
VFD Series that has voltage doubling options:
- 2XD Series – General Purpose, 6-pulse VFD
- 1LHX Series – Low Harmonic AFE, Phase Converting VFD
- 3LHX Series – Low Harmonic AFE, Three Phase VFD