Most switchers will go into an OFF state on over-voltage. Few of them have a buck-regulator that prevents over-voltage. The ones that do are very costly and large. Always use a Shunt when using a switching power supply to aid in suppression of bus over-voltage. Switching power supplies should be sized to provide maximum expected current for the entire motor system under the worst load considerations. This is because switchers have no “reserve” like linear power supplies do. When they reach maximum current, they shut down or reset.