Bi-Directional DC/DC Converter Reduces Costs

A consortium led by Prodrive has developed an approach to the configuration of DC/DC converters that will reduce the cost, weight and package space associated with electric vehicle battery packs. The system is said to address the spiralling costs of energy storage by increasing the voltage available at the traction motors.

To improve efficiency, electric motors require ever wider speed ranges; as speed is proportional to voltage, electric vehicles and hybrids are progressing from 300V to 600V systems. This creates a challenge because battery chemistry dictates the voltage per cell, so doubling the voltage with the same battery chemistry means doubling the number of cells, incurring cost, weight, and packaging penalties.

More cells, or a switch to an alternative chemistry, may also exacerbate challenges such as thermal management, availability, environmental protection and end-of-life recycling. To address this challenge, the consortium (which also includes the University of Manchester, HILTech Developments, Sloan Electronics , International Transformers and Newcastle University) has developed a bi-directional DC/DC converter that gives a 600V output from a 380V source and maintains its output even when the source voltage drops to as little as 200V.

The key is a new topology that delivers up to 97 per cent efficiency and is also low cost and compact. The power-handling capability is scalable, with development units rated at 50kW for full hybrid applications. The voltage of batteries (and fuel cells and supercapacitors) can fluctuate with changing load, but the Prodrive converter always presents the full voltage required by the motor. Vehicle architecture benefits from a reduced battery pack envelope and weight, and there is an overall cost saving.

GEOID Software Reduces Tool Costs

Blohm Jung has announced that at the Schleifring Grinding Symposium 2009, it will present, under the expression GEOID, a new development for compensation of contour faults in dressing tools. The example shows the quick manufacture of a blanking punch on the Vario D. GEOID was developed in conjunction with the Georg Simon Ohm University in Nuremberg.

The software for compensation of uneven wear in dressing tools is a further development of the automatic diamond adjustment by Blohm Jung and is used in conjunction with the CNC PA37K profile dressing device and the table version PA130TM. Topography of the cutting edge of the dressing tool can be determined with accuracy using GEOID. The correction values calculated are fed directly into the dressing program and create a perfect contour on the grinding wheel.

The result is an increased service life for the dressing tool, reduced costs of tools and improved contour accuracy. For profile grinding, different dressing systems are available for the Vario range of profile grinders by Blohm Jung. According to requirements, profiled crushing units, fixed-profile diamonds or swivelling diamond wheels are mounted on the grinding table. The company said a highlight of the range is the CNC PA37K head-dressing unit.

The function 'CD Abrichten' (continuous dressing), or parallel dressing cuts machining times by up to 50 per cent. Blohm Jung will also show how the GEOID correction software determines the actual contour of the diamond via a measuring probe and then corrects the dressing program accordingly. Therefore GEOID compensates for the wear in individual diamonds and diamond wheels, increases the usability of the dressing tools, and reduces the costs of tools.

Rubber Reduces Noise In Anti-Vibration Systems

Trelleborg Automotive has announced the introduction of Noise-Free Rubber, a self-lubricated, low-friction rubber formulation that overcomes noise issues associated with automotive applications.

The Noise-Free Rubber features improved dynamic properties while reducing noise in specific anti-vibration system components, such as anti-roll bar isolators, suspension bushings and engine mounts. The product has also been engineered to meet stringent fatigue requirements, the result of which is an increase in durability of around 50 per cent.

Sound Dead Steel Reduces Gas Pipeline Noise

Sound Dead Steel (SDS) was contacted by the Industrial Noise and Vibration Centre (INVC) to assist with a noise reduction programme for Scottish Power. The power station's main gas pipe work is 400mm diameter, with a reduction to 150mm at the metering section Close microphone measurements indicated noise levels as high as 100 to 110dB(A) with the dominant energy at frequencies >500Hz. SDS clad the pipeline with Sonphonon sound dead steel, fabricated and fitted split boxes to encase the valves.

After the final snagging was completed, the attached noise survey was carried out to determine the overall noise reduction for this project. The average noise reduction achieved within the GRF compound was approximately 8dB(A). The maximum reduction achieved was 16dB(A); this was adjacent the metering flow meter area. INVC noted that noise from adjacent cooling fans masked the full noise reduction benefits.

Noise reductions on plain pipeline measured 19dB(A), which clearly shows the effectiveness of the SDS cladding on standard pipe sections. Reductions of 7 to 8dB(A) were measured mid, up and downstream of the metering section using close microphone measurements. The reductions would have been greater, but pipe joint flanges have to be left open in case leakage occurs resulting in explosive conditions.

Novel Thermal Design Reduces Inverter Volume

Lenze has developed 8200 vector inverters using the 'cold plate' technique for cases where the inverter can be mounted directly onto a substantial heatsink. AC Tech (Lenze AG) 8200 Vector Inverters are available for power 0.55 to 90kW with three-phase supply. In the more popular smaller sizes up to 22kW, a space saving variant can reduce the requirement for panel space by up to 40%.

By dissipating the heat outside the cabinet, these 'cold plate' versions enable panels to have higher enclosure ratings. Alternatively a plate with external cooling by liquid or air can be used. The cold plate versions of the 8200 vector inverters have no heat fins, so heat generated is passed to the mounting plate and transmitted out of the cabinet.

In this way inverters require less mounting depth and the space savings are substantial. For a 1.5kW inverter the saving is 25%, rising to 40% for a 22kW inverter. Therefore panels can be smaller and costs reduced. As the heat is now transmitted to outside of the cabinet, requirements for a flow of cooling air through the cabinet are removed. Cabinets can be sealed and protection to IP65 is easier to achieve.

This is particularly advantageous in dusty conditions where any through flow of air would cause a dust build-up. Above 22kW the cold plate design is not available. However an alternative 'push-through' design can be used right up to 90kW. Here the Lenze Inverter Heatsink is mounted outside of the panel, gaining the advantages of panel space and enclosure as described. The concept of the 8200 vector frequency inverter is based on a modular system of complementary components.

Combined with a Lenze geared motor or a Lenze three-phase AC motor, it can be used to implement electronic variable speed drives for a multiplicity of applications. Compact: Side-by-side mounting saves space in the control cabinet. Integrated filters (optional) simplify installation. Flexible: The modular structure enables the inverters to be optimised for your application. This results in cost-effective but high-performance drive solutions. Whether as a "stand-alone" inverter with setpoint selection via potentiometer or a networked inverter with speed feedback in master/slave mode, the inverter functions can be adapted to suit every application.