This 50A PWM DC motor controller uses one chip TL494CN, 3 MOSFETS CSD18532KCS from Texas Instruments and Diode MBR3045V. The TL494 incorporate all the functions required in the construction of a pulse-width-modulation (PWM) control circuit on a single chip. Designed primarily for power-supply control, this device offers the flexibility to tailor the power-supply control circuitry to a specific application.
The TL494 contains two error amplifiers, an on-chip adjustable oscillator, a dead-time control (DTC) comparator, a pulse-steering control flip-flop, a 5-V, 5%-precision regulator, and output-control circuits.
The circuit diagram is based on PWM (Pulse Wide Modulation) to control the speed of a DC motor. PWM is controlled by TL494 which has the advantage that can be controlled by using the frequency 100Hz, with the rise and fall time of 10uS. PWM range can be adjusted from 0-100%. You can adjust the speed of a DC motor with a turn potentiometer VR5.
On this example we use DC motor rated with 350W and 19A continues current. We use 12V Lead Acid Battery 65A. 
On start up motor draw more than 50 Amps for couple of seconds after that it draws continuous 30A. We use 12V in order to test the DC motor Controller. If you use 24V than the motor draws from 15A to 19A.
PCB is aviable for the 50A DC Motor Controller, the pcb is real size!
- 50A DC Motor speed controller PCB
The Controller can be used for DIY Motor Electric Bike, Electric Scooters etc. If you like to increase the power, you should increase the number of MOSFET and diodes.