  Past work proposed an extension to finite control set model predictive
control to track both a current reference and a switching frequency reference,
simultaneously. Such an objective can jeopardize the current tracking
performance, and this can potentially be alleviated by instead limiting the
switching frequency. To this end, we propose to limit the switching frequency
in finite control set model predictive control. The switching frequency is
captured with an infinite impulse response filter and bounded by an inequality
constraint; its corresponding slack variable is penalized in the cost function.
To solve the resulting problem efficiently, a sphere decoder with a
computational speed-up is presented.
