How to electrically brake a brushless motor
The braking options are mechanical, dissipation, and energy recovery. However when the vehicle is at a stop, braking can only be via mechanical static friction or via electrical dissipation generating static counter-torque. Current in the windings is highest when the motor is not turning, because there are motoring coils and generating coils. When shaft speed is zero, there is zero back-EMF and the motoring coils absorb high stall current. The braking torque generated by this technique could develop enough heat to degrade the varnish or other insulation on the wires of the motor coils.
I anticipate this will be my final edit just to add this link to a pdf presentation for fairly complex effort to design a regenerative braking circuit with a BLDC motor:
http://ww1.microchip.com/downloads/en/devicedoc/regenerative%20braking%20of%20bldc%20motors.pdf
I would read the 16-page paper below, which uses a low voltage BLDC example to explore the issues of energy-recovery braking and then perform experiments with small inexpensive systems that might get destroyed, before undertaking any effort to design a higher power system. Mechanical brakes via electronic actuation are probably the best solution and perhaps the only viable non-destructive solution for certain operating conditions.
Energy-Regenerative Braking Control of Electric Vehicles Using Three-Phase Brushless Direct-Current Motors, Energies 2014, 7, 99-114; doi:10.3390/en7010099
https://pdfs.semanticscholar.org/eb63/34a18cda052716e59043a702e2da14a528dc.pdf
Here is another 7 page paper with discussion of electrical braking BLDC. It also says mechanical brakes are necessary for static braking.
International Electrical Engineering Journal (IEEJ) Vol. 3 (2012) No. 2, pp. 784-790ISSN 2078-2365 Page 784 Rakesh and Narasimham, Different Braking Techniques Employed to a Brushless DC Motor Drive used in Locomotives:
http://ieejournal.com/Vol_3_No_2/Different%20Braking%20Techniques%20Employed%20to%20a%20Brushless%20DC%20Motor%20Drive%20used%20in%20Locomotives.pdf
When conducting tests on a motor with no load or gearbox the dynamic braking will be very rapid due to only the rotor inertia of the BLDC. Adding inertia via a direct load or gearbox coupled mechanical load prolongs the spin up time and braking time. Heavy braking current flows for a longer period of time when more kinetic energy must be dissipated in the braking resistance or passed back into the battery power source. Heat can build up and exceed the safe operating area of electrical components with improper thermal design.
This video shows a 24 volt electro magnetic brake device:
https://www.youtube.com/watch?v=HrQPAZXsP6I