What are the options for discharging a DC link?
Single Pulse: Simple, but large resistances needed
When the DC link is discharged using a single pulse, all the energy is applied disproportionately to the resistor. As a result, the resistor must process a high amount of energy, especially in the initial phase, which then causes extremely high temperatures. On the other hand, only a low level of energy is converted at the end of the discharge.
For the resistor to withstand the enormous heat in the beginning, it must have a high thermal capacity. This means that it must be correspondingly large. Only in this way can it absorb the heat and, if necessary, dissipate it to a cooling medium.
The advantage of this method is that no complex control electronics are required to activate the discharge of the DC link. At first glance, the effort required by the customer is therefore low and theoretically cost effective.
The disadvantage, however, is that the unregulated discharge method described above, requires a larger housing and a large cooling surface area due to the high energy conversion during the initial phase. The larger the housing and the cooling surface of the resistor, the more expensive the costs are.