Application Solutions

Patented technology enhances and simplifies QM module design

Posted by Martin on January 30, 2020
QM SA module

TDK-Lambda’s QM series of modular power supplies utilises pre-built parts or parts that can be quickly assembled to demand. These assemblies are configured to produce power supplies that offer between 1 and 18 outputs ranging from 2.8V to 105.6V, capable of delivering between 550W to 2,000W in total output power.

Internally, the QM converter module takes the applied input voltage and converts it into a regulated high voltage bus. This voltage is used by DC-DC converter modules to deliver isolated, regulated voltages to the user’s loads. An extensive range of output modules with power capabilities of up to 1200W make it possible to achieve almost any combination of voltage and current.

In some configurations, low power outputs with ratings of 150W or less are requested. Previously the solution was to offer the QM “SB” modules rated at 150W to 300W, which had a cost impact. A development for a lower cost “SA” module was proposed, with a 5V 75W output and 12V, 15V and 24V 150W outputs.

Resonant DC-DC converters based on LLC series circuits are widely used in power supplies as they offer high efficiencies. One drawback is that the converter is difficult to control when operated over a wide range. With extensive experience in power supplies with digital control, the TDK-Lambda R&D team designed a circuit using a digital controller and in-house developed algorithms. A patent has since been granted for the technology.

Using multiple sensing signals an emulated current-mode control was created. This phase mode control arrangement ensures that the converter has a greater loop stability across a wider range of operating conditions. This has resulted in an improved output voltage response when sudden changes in load currents occur, producing faster and improved recovery times.

The use of the digital controller in the SA module reduced the number of surface mount components by 42%. As the SA module is half the power of the SB module, four TO-220 power devices were replaced by SMT semiconductors, requiring no external heatsinks or thermal insulating pads. Overall 40% of the through-hole components were eliminated.

The lower cost SA modules are now included in the QM online configurator, which automatically selects the most suitable modules for the user’s choice of output voltages and currents.

All models in the QM series feature low acoustic noise and full MoPPs isolation. With medical and industrial safety certifications, the QM series addresses a wide range of applications, including BF rated medical equipment, test and measurement, broadcast, communications and renewable energy applications. The QM series is certified to IEC/EN/UL/CSA 60601-1, ANSI/AAMI ES 60601-1, IEC/EN 61010-1 and IEC/EN/UL/CSA 60950-1 with CE marking for the Low Voltage, EMC and RoHS Directives.