DC motor drive with high torque at low speeds

DC drives are still very important especially for low voltages and low power (e.g. in cars and robots). In this paper a converter is analyzed which makes it possible to control the voltage across the machine (and therefore the speed) from zero to input voltage with a quadratic dependence of the duty cycle. This enables high torque at low speeds with better efficiency. The circuit is explained, the model of the drive, the design of the devices, and some experimental results are given.