CM600DU-24FA IGBT – Removal of RTC over-current protection

The real-time current control (RTC) that can found in some IGBT modules is a protection against short circuits in f.ex. motor drives where they could have been used.

The conditions on which the RTC acts is however sharing area with using IGBT bricks in Tesla coils, as the RTC will never interact while operating the IGBT within its Safe Operating Area (SOA) there is still a risk that it will be activated when driving a IGBT hard in a DRSSTC where it could be used to switch currents many times its rating.

Below is a quote from a Powerex paper on how the RTC works and behaves. I added a few outlines and extrapolated the graph to show the typical 24 VDC gate drive in a DRSSTC.

[1] 4.0 RTC Description and Behavior

F-Series IGBTs include an integrated real-time current control (RTC) circuit for protection against short circuits, which was originally developed for intelligent power modules (IPMs). The RTC is a separate chip wire-bonded directly to the IGBT die and mounted adjacent to it. During normal operation of the device, the RTC is effectively “transparent” to the gate driver. Its power supply is drawn from the main collector-emitter path of the IGBT, so it imposes no additional drain on the gate driver. The RTC is connected to a current mirror emitter on the trench IGBT chip. A simplified diagram of this is shown in Figure 3.

When the IGBT operates in a short circuit, the RTC detects the excessive current in the IGBT and reduces the gate-emitter voltage to limit the short-circuit current. The gate-emitter voltage is reduced to less than 12V, compared with the normal recommended value of 15V. The effect of gate-emitter voltage on short-circuit current is shown by Figure 4. It is important to note that the RTC acts only to limit short-circuit current; it does not switch off the IGBT. Therefore the gate driver circuit should be designed to ensure that the IGBT is turned off within 10µs of a short circuit occurring. The RTC limits the short circuit collector current to 2-4 times rated current, depending on the junction temperature of the IGBT and the short circuit di/dt.

The minimum trip threshold for the RTC is 2 times the rated current of the device and occurs at high Tj and high di/dt. Therefore operation of the IGBT within its normal switching SOA is unaffected by the presence of the RTC

In the following video I show and explain where to locate the RTC circuit and how to disable it with a simple tool like tweezers. Side cutters can also be used but it will make a bigger mess and ruin more of the protective goop that surrounds the die and bonding wires.

References

[1] Powerex, “Featured Products Technology”

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Kaizer DRSSTC III update #6 – First full power test after removing RTC

After cutting out the bonding wires to the RTC circuit of the CM600DU-24FA IGBT bricks, which we thought could be one of the reasons that we were not able to trip the 1500 A OCD setting, we had a short test run to witness performance. I will do a video with more details of the real-time current control removal later.

While it might have limited the operation a little bit, it was nowhere near hindering performance, this coil is just so high impedance that it runs long on-times instead of high peak currents.

Fed with 3×400 VAC through a variac resulted in a 0.6 power factor. After roughly 8-10 test runs at up to 2 minutes, with peak power consumption hitting 14 kW at 500 BPS, 200uS, the total power consumption over all the tests was 0.281 kW/h, 0.331 kVAr/h and 0.438 kVA/h.

First video shows the coil running 120-500 BPS at somewhere around 200 uS on-time. Peak power consumption from the 3×400 VAC supply was around 14 kW. Sparks are 3 meters to ground and somewhat shorter to the ladder.

Second and third video show tests with a static load, peaking at about 10-14 kW depending on MIDI or interrupter is used.

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Astro HVO-Vario G 38, teardown of a 862 MHz cable TV amplifier

These are highly modular cable TV amplifiers, they are set up by using a wide range of different insert cards with different frequency ranges or options. These are 38 dB amplifiers in the range from 47 to 862 MHz.

This particular amplifier is set up for 862 MHz, 42 channels and has a return path amplifier for keeping signal strength on the line good. The line equalizer is used to adjust for how close to the community amplifier the house is located, the further away, the less attenuation is needed.

These small amplifiers are used in houses where it is not practical to use a receiving antenna to get the signal from the broadcast headend transmitter. They are called a “service drop”

Instead CATV is used, short for community antenna TV, a large receiving antenna is used, a cable connection runs out to every house in the neighborhood and each house has one of these amplifiers. The return path amplifier can also send some of the signal back into the line to keep the signal good enough for the next house.

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Finished project: Merlin Gerin PM700 power meter

Two days ago I conducted the first successful resistive load test of a 3 phase power meter that can measure voltage, current, power consumption, harmonic distortion and power factor.

Read all about the construction and see all the pictures and video demonstration here.

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Finished project: 3 phase 13A Lübcke variac

Yesterday I conducted the first successful resistive load test of a 3 phase 13 A variac stack that has been enhanced with safety and monitoring options.

Read all about the construction and see all the pictures and video demonstration here.

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Winners of a DRSSTC UD2.1 board

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Seven users entered the lottery for a board by leaving a comment with a email address and through a gentleman agreement subscribed to the various channels related to this site.

Two random numbers have been drawn between 1 and 7 using random.org 

The two lucky winners are schiro marc and David! Thank you very much to all the other contestants for subscribing.

I will contact you regarding shipping details

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Win a DRSSTC UD2.1 board for just a like/subscribe

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I got two spare DRSSTC driver boards and you now have the chance to one of them home. It is a Steve Ward UD2.1 board as you see in the picture, with free shipping.

All you have to do is one or all of the following things:

  • Like my facebook page this is where you get the most frequent updates.
  • Subscribe to my youtube channel for instant updates on new videos.
  • Subscribe to my newsletter for the latest posts on this website, you can find the “Subscribe to Blog via Email” out in the right menu column.

Afterwards make a comment to this post about which service you subscribed to and use a valid email address, so that it is possible for me to contact you for shipping details if you are drawn as a winner.

There are 2 boards up for lottery, drawn as random numbers from the list of comments on this post. Winners will be announced on facebook and this website at Monday, August 22nd, 2016.

 

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Nokia Siemens Networks Flexi WCDMA teardown: Antenna (part 3 of 3)

Nokia Siemens Networks Flexi Multiradio BTS is a GSM/EDGE, WCDMA/(I-)HSPA, and LTE base station for use in mobile telecommunication antenna networks. A network that you use daily on your cellphone.

Part 1: System station and Part 2: Power amplifier

This is an obsolete Kathrein XPol 2-port single band panel antenna. The 2 ports means that it actually has 2 antennas in the one unit. There is a main and a diversity antenna (90° polarized to each other) for 1710 – 2200 MHz (1800-2100 MHz mobile bands).

Newer antennas now have to allow for 700 LTE, 850 UMTS, 900 GSM and UMTS, 1800 LTE/GSM, 2100 UMTS and 2300 LTE so they have considerably more different antennas inside of them.

Each of the two antennas consists of a co-phased stacked array of dipoles. There is a total of 8 dipole pairs per antenna.

The antenna housing also includes a RET (Remote Electrical Tilt) which allows adjusting the direction of the electromagnetic lobe without climbing the tower or even moving the panel. By using a phase shifter located on the backside, the lower elements are phase delayed to electrically drop the front lobe down, without physically tilting the panel.

The phase shifters are actuated via the white glass fiber rod running up the side of the front of the antenna. The position of the arm inside the phase shifter is adjusted by turning the screw mechanism next to the connectors to move the rod.

Specifications

Frequency bands: 700, 800, 850, 900, 1800, 1900, 1700/2100, 2100, 2300 and 2600 MHz.

Maximum capacity: Up to 6+6+6 GSM or 4+4+4 WCDMA or 1+1+1 LTE at 20 MHz or flexible combination of the above technologies in concurrent mode.

Multi-radio configuration: 1 Flexi 3-sector RF module + 1 system module for GSM/EDGE + 1 system module for WCDMA/HSPA and LTE. Remote Radio Head (RRH) solution also supported.

RF power amplifier technology: Multicarrier power amplifier (multi-standard)

Height x width x depth: 133 x 447 x 560 mm per module, indoors and outdoors. Fits in any 19” rack.

Weight: 25 kg per module

Operating temperature range: -35 °C to +55 °C

Power supply: 40.5 – 57 VDC, 184 – 276 VAC with power module

Typical power consumption: 790W for combined GSM and WCDMA site

Output power: 240 W per RF module or 40 W + 40W per Remote Radio Head (RRH)

Ingress protection class: IP 65

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Nokia Siemens Networks Flexi WCDMA teardown: Power amplifier (part 2 of 3)

Nokia Siemens Networks Flexi Multiradio BTS is a GSM/EDGE, WCDMA/(I-)HSPA, and LTE base station for use in mobile telecommunication antenna networks. A network that you use daily on your cellphone.

Part 1: System station and Part 3: Antenna

The following 12 minute video shows the teardown step by step with explanations, high resolution pictures of content is further down this post.

In the above pictures we see the tuning cavities of the band pass filter for the transmit and receive channels for the antenna connections. There is a total of three separate band pass filters. Each filter consists of a, from the left, receiving band pass filter, in the middle transmitting band pass filter and at the right another receiving band pass filter.

Most of the enclosure work also includes the small drums for tuning the cavities with the adjustable pins seen in the second picture, but in the transmitting cavities the silvered drums are, very unusually, made of a ferrous metal that is attracted with a magnet. Earlier I have only seen these as silver plated brass, but it does seem that even cheaper metals with enough silver plating can do the same job.

The tuning pins are however of a extraordinary good quality, very smooth surface with gold plating.

In the above pictures we see the three-sector RF amplifier boards, there is a total of three of these boards. The board itself is a Aluminium Silicon Carbide heat sink on which all the components are directly mounted. The input connectors in the bottom of the pictures leads the signals through a coupler to the Freescale / NXP MD7IC2250GN integrated RF LDMOS which is a 2-2.2GHz 5 Watt amplifier. From here the signal is routed via a Aeroflex P131103 output filter to the Anaren X3C21P1-05S Xinger III coupler where it distributes to the three output amplifiers through a additional coupler. The last stage of amplification is handled by three Ampleon / NXP BLF8G22LS-160BV Power LDMOS transistors which are 2-2.2GHz 160 Watt transistors, but in this setup used for a combined 60 Watt output of the module. The output filter is a Aeroflex 5608098 ISO-2100-33CW with a built in PT-100W 50Ω attenuation.

In the above pictures we can see that there is a massive amount of ceramic capacitor filtering on the input DC voltage that could range from 40.5 to 57 VDC.  The input is protected by varistor’s, chokes and diodes.

The digital signal processing board has its own power supply seen down in the right corner and each power amplifier module also has its own power supply which consists of a controller, transistors, planar transformer, output capacitors and choke to regulate the voltage very tight for the amplifier. There is also a massive amount of ceramic capacitors for filtering the voltage right up to where is connects to the modules.

In the above pictures we see the digital signal processing board with the three optical inputs in the bottom of the picture. Digital data is processed by the Freescale / NXP MCP8378 PowerQUICC II CPU and its associated Altera Cyclone IV FPGA (it should have been IV, not II on the picture).

Translation and splitting of the telecommunications protocol data and selection of different drive modes, if the amplifier is used for GSM, EDGE, HSPA, WCDMA or LTE, is done by the Nokia Siemens Networks marked ICs. The NSN 4371734 MURKKU2 and P155718 MERA CPUs are impossible to locate any data on, they do however have great resemblance to the NEC marked CPUs I have seen in GSM/EDGE amplifiers.

The Skyworks SKY65338-21 IC is a GSM 450-470 MHz transmit / receive front end.

The AD9122 TxDAC is a 16-Bit digital analogue converter that translates the telecommunications protocol into a analogue data stream with as much as 1230 MSPS. The analogue signal is amplified by the Skyworks SKY65387-11 IC that is a WCDMA variable gain amplifier.

A part of the receiving signal processing and filtering are the TriQuint 856731 192 MHz SAW filters that form a network to feed into the AZ4246 (ADS4246) which is a dual 14-Bit ADC analogue digital converter that translates the analogue data stream back into the telecommunications protocol with a speed of 160 MSPS. This section is most likely related to the GSM part of the receiving amplifier.

 

Specifications

Frequency bands: 700, 800, 850, 900, 1800, 1900, 1700/2100, 2100, 2300 and 2600 MHz.

Maximum capacity: Up to 6+6+6 GSM or 4+4+4 WCDMA or 1+1+1 LTE at 20 MHz or flexible combination of the above technologies in concurrent mode.

Multi-radio configuration: 1 Flexi 3-sector RF module + 1 system module for GSM/EDGE + 1 system module for WCDMA/HSPA and LTE. Remote Radio Head (RRH) solution also supported.

RF power amplifier technology: Multicarrier power amplifier (multi-standard)

Height x width x depth: 133 x 447 x 560 mm per module, indoors and outdoors. Fits in any 19” rack.

Weight: 25 kg per module

Operating temperature range: -35 °C to +55 °C

Power supply: 40.5 – 57 VDC, 184 – 276 VAC with power module

Typical power consumption: 790W for combined GSM and WCDMA site

Output power: 240 W per RF module or 40 W + 40W per Remote Radio Head (RRH)

Ingress protection class: IP 65

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Nokia Siemens Networks Flexi WCDMA teardown: System station (part 1 of 3)

Nokia Siemens Networks Flexi Multiradio BTS is a GSM/EDGE, WCDMA/(I-)HSPA, and LTE base station for use in mobile telecommunication antenna networks. A network that you use daily on your cellphone.

Part 2: Power amplifier and Part 3: Antenna

In the above picture we  see the first DSP board that was visible when the first shield was taken off the enclosure. Please watch the following video to get a detailed description as I take it apart. Details on all the ICs, CPU and controllers follows in the pictures below the video.

In the above pictures there is a Freescale SC8548CVTANGB PowerQUICC III CPU which 2-16 GB Samsung memory. Other ICs include Texas Instruments ACH973, NXP LVC823A and Spansion GL512P12FFIV1.

In the above pictures there is Texas Instruments TMS320TC16488ZUN DSP processor, Lattice POWR1220AT8 programmable power supply controller and Marvell 88E6185-LKJ1 10-port Gigabit ethernet switch. There was a total of 14 Texas Instruments TMS320 DSP processors with each 28800 MIPS in processing power, combined that is over 400000 MIPS and corresponds to calculating power of 3x Intel Core i7 4770K CPUs.

In the above pictures there is a TDK Lambda iQE48025A050V-0A1-R switch mode power supply with planar transformers that uses gold traces in the PCB as windings.

In the above pictures there is a four ethernet ports out to the left which connects to the isolation transformers Pulse HX5004NL and HX1188NL. The network interface is managed by the Marvell Alaska 88E1145 Gigabit quad-port ethernet transceiver.

In the above pictures there is a Epson Toyocom OX-6500GG temperature controlled 30.72 MHz crystal oven that is stabilized by always keeping it at a constant temperature. Above it there is a Altera Cyclone II FPGA from the EP2C5 family and this model has 4608 LE’s, 119,808 RAM bits and 158 user I/O pins.

In the above pictures there is Texas Instruments TMS320TC16488ZUN DSP processor, Lattice POWR1220AT8 programmable power supply controller, Marvell 88E6185-LKJ1 10-port Gigabit ethernet switch, NEC 4374360MUKSU2 CPU which is unknown to me, a Spansion GL01GP13FFIV1, NXP LVC373A, Texas Instruments ACH973 and a Toyocom TCO-2111N2 153.6 MHz crystal.

Specifications

Frequency bands: 700, 800, 850, 900, 1800, 1900, 1700/2100, 2100, 2300 and 2600 MHz.

Maximum capacity: Up to 6+6+6 GSM or 4+4+4 WCDMA or 1+1+1 LTE at 20 MHz or flexible combination of the above technologies in concurrent mode.

Multi-radio configuration: 1 Flexi 3-sector RF module + 1 system module for GSM/EDGE + 1 system module for WCDMA/HSPA and LTE. Remote Radio Head (RRH) solution also supported.

RF power amplifier technology: Multicarrier power amplifier (multi-standard)

Height x width x depth: 133 x 447 x 560 mm per module, indoors and outdoors. Fits in any 19” rack.

Weight: 25 kg per module

Operating temperature range: -35 °C to +55 °C

Power supply: 40.5 – 57 VDC, 184 – 276 VAC with power module

Typical power consumption: 790W for combined GSM and WCDMA site

Output power: 240 W per RF module or 40 W + 40W per Remote Radio Head (RRH)

Ingress protection class: IP 65

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