DC-DC converter circuits have been used extensively in commercial low voltage (3 V-50 V) power control applications because of their speed and high efficiency. DTI has scaled this familiar circuit topology to high voltage (160 kV) and high power (3 MW) for power conversion applications. DTI combines many low voltage semiconductor components, such as IGBTs, in series, into a single high voltage switch. Recent improvements in voltage and current handling capabilities of IGBTs enable the design of very fast opening and closing switches. Two circuits, a buck regulator (down-converter), and a boost regulator (up converter), are illustrated in the figures on this page.

The opening and closing of the switch is controlled by Pulse Width Modulation (PWM), which provides feedback of the voltage or current delivered to the load. The pulsed output of the converter is then filtered for low ripple. These circuits act as nearly lossless DC transformers with output power equal to input power.

PowerMod buck regulator power supplies are highly reliable. Isolated switch module failures do not force the power supply to shut down because the solid-state components have full soft-fail capability. DTI delivered the buck regulator power supply shown to the left for a high power tube testing application.

An emerging application of DTI's DC-DC converters is solid-state DC power distribution and control. The benefits of using solid-state technology include:

  Simplicity & Scalability- Solid state DC-DC conversion eliminates 60 Hz SCR regulators and series-pass tube regulators. DTI's modular design can be scaled to different power requirements and delivered in virtually any combination of voltage (up to 200 kV) and current.

  Efficiency- A 20 kHz, 100 kV solid-state switch has nearly two orders of magnitude greater capability for high speed voltage regulation than a 60 Hz SCR controller. Its voltage drop is only 200V (4 kW, or 0.2%) vs. the much larger 10-20% voltage drop associated with vacuum tube systems. The overall efficiency of our DC-DC converters is estimated at greater than 98%.

  Cost Savings- In a typical 2 MW CW system, each percent of inefficiency wastes approximately $10,000 per year in electricity costs . Replacing a voltage regulation tube with a solid state buck/boost regulator creates $100K-$200K per year in cost savings, easily justifying their use in virtually all high power systems. In addition, increased efficiency significantly reduces the facility cooling requirement.

  Reliability- Each high voltage switch consists of a number of power modules in series which are typically derated by 30% or more. IGBTs, the main component in a power module, are rated to have MTBFs in the millions of hours. These modules, if they fail, always fail shorted, permitting continued operation of the switch system. Failed individual switch modules can be replaced during periodic maintenance without affecting the operation of the system.

  Flexibility- DTI switches can provide pulses from 1 microsecond to CW in response to arbitrary pulse commands.