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Back-to-Back Buck-Boost Converter

Through the proper configuration of two OZIP-DC/DC Intelligent Power Modules, it is possible to transfer energy between two DC power sources with overlapping voltage ranges.  In this configuration the DC-DC Converters are connected “back-to-back” such that they share a common, intermediary rail voltage.  The following figure illustrates a “Back-to-Back” Buck-Boost DC/DC converter. The Boost converter […]

A Second Generation Digital SCR Controller

The OZSCR-2000 is our latest SCR Firing and Control board offering, built upon the successful OZSCR-1000 digital control platform. This second-generation controller uses a Texas Instruments Piccolo processor and provides all the original digital control features, including: Jitter free, Digital Phase Locked Loop (PLL) Digital Control Laws for Closed-Loop Applications 100% Software Configurable One of the […]

Effects of Cable Length on SCR Drive Waveforms

A general rule of thumb when driving SCRs is to use as short a cable as possible in order to provide the most efficient turn-on characteristics. As cable length increases, two important parameters are degraded: inductance and series resistance. In order to minimize inductance, gate drive cables should be constructed in a manner that tightly […]

SCR Driver Board Firing Pulses

The newly introduced OZSCR-1000 SCR firing board is capable of controlling a wide range of commercially available SCRs.  SCRs operate similarly to diodes, with current flowing in only one direction through the device.  In both SCRs and diodes, current cannot pass through the device until the anode is at a higher potential than the cathode, […]

Controlling Power with SCR: Phase Angle vs Zero Crossing Mode

When controlling power with SCR-based designs, engineers are faced with the decision of what type of control mode to use; zero-crossing or phase angle control. In order to make the right decision, the design engineer must understand the advantages and disadvantages of both control modes as well as the attributes of his or her load. […]

SCR Control Goes Digital

SCR Control circuits and products have been around for decades. An industry-standard SCR controller typically consists of an SCR firing circuit, a phase-locked loop (PLL) or line synchronization circuit, and a means of controlling the firing angle of the SCR device, typically a 0-5V or 4-20mA analog input. While there are currently several industry-standard SCR […]

Porting Free Modbus for the SCR-1000 Control Board

For our SCR-1000 board, we needed to implement a Modbus stack for communicating with the board over RS-485. We have previously ported the FreeMODBUS stack to the Texas Instruments 28335 for use on the OZDSP-3000 board, so again we selected FreeMODBUS for use on the Stellaris part that controls the SCR-1000. The SCR-1000 only requires the use of the RTU mode […]