Patent ID: 8663200

Claim:
A negative pressure wound therapy apparatus comprising: a wound dressing; a fluid collection container; a vacuum pump comprising a pump motor; one or more tubes configured to at least channel a flow of fluid between said wound dressing, said fluid collection canister, and said pump; a pressure sensor configured to measure a pressure in one or more of said one or more tubes and to generate a pressure sensor voltage reflecting pressure in one or more of said one or more tubes; a control circuit for controlling the pressure in said one or more tubes without using a processor, the control circuit comprising: a pressure controller for controlling the pump motor, the pressure controller comprising: a difference circuit configured to: receive the pressure sensor voltage from the pressure sensor; receive a desired pressure voltage from a user; and provide a difference signal comprising an amplified difference between the desired pressure voltage and the pressure sensor voltage, wherein the difference circuit provides proportional control; and a pulse width modulator configured to generate a motor control signal responsive to the difference signal, the motor control signal configured to control a speed of the pump motor; and a stall controller for preventing stalling of the pump motor, the stall controller comprising: a comparison circuit configured to generate an override signal based at least in part on the difference signal and at least one reference signal, the override signal configured to prevent stalling of the pump motor; and stall logic configured to output a combined control signal based at least in part on the override signal and the motor control signal, the combined control signal configured to control the pressure in said one or more tubes without stalling the pump motor.