One of the considerations involved here is what proportion of the AC cycle the diodes are expected to be conducting. In cases where the conduction angle is only a few degrees of the AC cycle, reverse recovery losses can be significant if a slow diode is used at high frequency. Also, as conduction angles decrease for a given fixed RMS output current, the peak current in the diodes increases.
Still, 3.7 kHz is not all that high a frequency in the electrical world, and packaged rectifiers targeting 60 Hz applications may be quite suitable, as long as an allowance is made for some increased dynamic losses. “Slow” diodes typically recover in a few microseconds, or roughly 1% of a full cycle at 3.7 kHz, whereas fast diodes recover in a few tens of nanoseconds or less, and some of the newer silicon carbide rectifiers have essentially a zero reverse recovery time. On the other hand, slow diodes tend to create fewer RF emissions problems. The slower fall time of the reverse recovery current contains lower frequency spectral content and doesn’t induce as much voltage in parasitic inductances within the circuit as the high di/dt of a fast diode.
Also, there is the consideration of mechanical constraints; some packages may work better than others and the possibility of assembling a rectifier from individual diodes or series-connected diode pairs should be considered.
That said; try the IXYS FUO22-12N-ND (standard recovery) or the FUE30-12N1-ND (fast recovery) for the 10 A application. These are comparatively inexpensive, compact, and provide the option to use either a standard or fast diode without changing the package.
Figure 1: Schematic of the IXYS FUO22-12N and FEW30-12N1 bridge rectifiers.
