Page 96
www.us-tech.com
May, 2018
New Approach to IGBT Control: Electrical Plugging — Optical Transmission
By Rainer Bussmann, Senior Product Manager, and Jonas Diekmann, Special Editor, HARTING Electronics
ndustrial drive engineering, with its automated manufacturing processes, would not be possible without electric motors. IGBT (insulated-gate bipolar transistor) semiconductor elements control powerful electrical drives that are connected by polymer optical fibers for the necessary isolation. This solution takes up a lot of space and is very sensitive. HARTING is now offering a new, minia- turized approach to IGBT control.
I
Electric motors in drive technology can con- sume kilowatts or even megawatts of power. At constant speeds, their control technology is rela- tively simple. But, the motor speed often needs to be adjusted, making the whole system much more complex.
In higher power classes, such as traction con- trol, or train and ship propulsion systems, the speed is controlled by IGBT semiconductors. These devices are able to switch great loads with very lit- tle driving power. The signals required for IGBT control are transmitted along polymer optical fibers, as they have very high isolation and can handle high voltages. Currently, six IGBT driver boards are required per phase to control a three- phase motor. These polymer optical fibers enable interference-free and electrically isolated signal transmission.
IGBTs in Railway
Especially in locomotive applications, IGBTs provide redundancy so that the controller board can transfer the function to the redundant compo- nent, ensuring the functionality of the system if an IGBT fails. This is in addition to a doubling of the optical transmission distances.
In the past, individual fibers would be used to connect the controller and driver board. The elec- tro-optical signal conversion takes place in the transceivers of the circuit board, with optical con- tacts to connect to the fibers. Each optical fiber has an individual port with the transceiver in it, on the driver board, as well as the controller board. This
Conventional optical elements were devel- oped mainly for industrial applications with wide temperature ranges and high levels of vibration, but only offer the fibers a simple strain relief. What is also important is that the optical interface needs to be protected from dirt and contamination. This makes protective covers necessary when unplugged.
In the past, if a transceiver were to break, one had to disconnect, replace and reconnect the entire board and all of its contacts, which takes consider- able time and labor. In partnership with estab- lished railway vehicle manufacturers, HARTING has developed a transmission solution that involves relocating the controller board’s trans- ceivers to a pluggable module. This integrates the optical interface.
Pluggable Transceiver Module Pluggable IGBT module.
solution eats up a lot of space on the controller board, making it unnecessarily large. Another disadvantage is that the various polymer optical fibers must be plugged in at the right places during installation and service calls, as each fiber must be connected to the driver and controller boards individually. This requires time and must be done carefully as it is relatively easy to mix up the senders and receivers. To guarantee the quality of the fiber end surface, the cables are prefabricated and can also be individually installed by the user on site.
For the electrical plugging and system hous- ing, the company relies on components from the DIN 41612 range. The DIN housing is made from die-cast zinc and meets the railway market’s requirements for robustness and EMC. It offers the possibility to run the cables straight or at angles, incorporating kink protection and strain relief for the fibers.
The circuit board in the DIN housing is able to accommodate series resistors and decoupling capac- itors for error-free control of the optical elements, and to mitigate interference. The electrical contacts in the DIN 41612 range are also resistant to micro- vibration wear and are themselves tested and
Continued on next page
Manufactured in the U.S.A. since 1966
www.westbond.com
1551 S. Harris Court Anaheim, CA 92806 Tel 714·978·1551
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