referring now to fig5 and back to fig2 it may be seen how the switching units 18 may be readily joined with one another the switching unit 18 may be provided with a female threaded connector member 46 at one end and a male threaded connector member 48 at an opposite end the member 48 may be threadably inserted into the member 46 to produce a switching module 50 the switching module 50 may comprise any number of the switching units 18 which may be connected in series or in parallel the switching module may be constructed to meet various capacity requirements of the control system 10 of fig1 referring now to fig6 a switching module 60 is shown in a planar configuration the switching module 60 may comprises a mounting board 62 for the igbt 39 s 30 coolant channels 64 may be positioned on opposite sides of the mounting board 62 in this regard the switching module 60 may provided for cooling on two sides of the igbt 39 s 30 a pcm tank 66 may be positioned in contact with the coolant channels 64 as described above with respect to the switching unit 18 in fig4 the pcm 42 may act as a heat absorbing buffer the coolant channels 64 may be configured to accommodate steady state heat dissipation the pcm tank 66 may function to absorb increases of heat dissipation that may result from transient loading of the switching module 60 referring now to fig7 1 7 2 and 7 3 various switching modules are illustrated as illustrated in fig7 1 four of the switching units 60 may be configured to produce a vertically stacked switching module 71 as illustrated in fig7 2 four of the.