Comparison of Different Switch Technologies C H Gough

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Comparison of Different Switch Technologies

C H Gough

Introduction

This Note is one of a series, documenting the development of the five Storage Ring Kicker systems for the SLS. The performance of three different types of switch module from Behlke Electronic GmbH were compared:

HTS 61-240-SI Standard IGBT 6kV / 2.4kA 2816DM HTS 61-160-FI Fast IGBT 6kV / 1.6kA 3080DM HTS 80-1000-SCR SCR 8kV / 10kA 2332DM

As in previous Notes, the small differences between modules are found by comparing waveforms from two different pulsers.

Shape Comparison

The difference signals were taken between two pulser cabinets, with strictly only the switch modules swapped. The nominal operating voltage for all tests was 2000V, corresponding to about 2kA (the nominal operating value is 2.6kA).

For untrimmed measurements, a single charging power supply was used, with a splitter box in the HV cable; in this way the two pulsers have strictly identical voltage. For trimmed measurements, two separate charging supplies were used.

The waveforms in Fig.1 show the performance of three standard IGBT modules. On one untrimmed intercomparison, a difference of about 1.5% was found. However, the differences were easily reduced with voltage trimming only, and the result was not too sensitive to timing changes.

The waveforms in Fig.2 show the performance of three fast IGBT modules. Unfortunately, these modules had been used previously, so there is possibility that Module 3 was damaged. The characteristics were not easily trimmed.

The waveforms in Fig.3 show the performance of three standard SCR modules. In this case, careful trimming of inductance, voltage and timing reduced the difference magnitude to about a half of the untrimmed value. The difference is sensitive to timing differences of 1ns.

The waveforms of Fig.4 compare the switch and load voltages of the IGBT and SCR switches. The slower SCR switch has high voltage for around 1s; the good matching of the current waveforms is very surprising, since switch voltage difference of only 2V in 2000V corresponds to 0.1% error.

Conclusion

These tests were arduous and expensive; further tests are should be avoided. While not conclusive, the results indicate that the standard IGBT technology is the most suitable, with static amplitude trimming to give the pulser difference below 0.1%.

The slower SCR modules are also reasonable although the high switch voltage during the first microsecond makes the trimming delicate.

The definitive measurement is the electron beam position in the Storage Ring during and after the pulse; electron beam movement is a complex convolution of the characteristics of the four kickers. Calculation of dynamic time and reactance corrections for the pulser is considered too complex. Dynamic amplitude trimming is feasable, and would require maybe ten pulses without injected beam to find the optimum values.

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(IGBT1)-(IGBT2), cursor 1%, no trimming

(IGBT1)-(IGBT3), cursor 1%, V=20V, t=0

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(IGBT1)-(IGBT3), cursor 1%, no trimming

(IGBT3)-(IGBT2) cursor 1%, no trimming

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(IGBTFast3) - (IGBTFast2), cursor 5%, V=115V, t=0

(IGBTFast3) - (IGBTFast1), cursor 5%, V=95V), t=0

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(IGBTFast1) - (IGBTFast2), cursor 1%, V=102V, t=0

(SCR1) - (SCR2), cursor 1%, no trimming

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(SCR1) - (SCR2), cursor 1%, V=-13V, t=+4ns

(SCR3) - (SCR2), cursor 1%, V=+12V, t=0ns

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(SCR3) - (SCR1), cursor 1%, V=+12V, t=-1ns

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SCR3 Switch voltage and load voltage

IGBT3 Switch voltage and load voltage