Dialysis system having reduced valve noise and valve position detection

A method of determining valve position in a medical fluid system, the method comprising:

• transmitting, by a microcontroller having a processor, a control signal for closing a valve, wherein the valve is configured to control a fluid flow in the medical fluid system, wherein the valve is open at least before the control signal is transmitted, and wherein the valve comprises a housing, a solenoid coil, and a plunger;
• applying, via a driving circuit, power to the valve to measure a voltage across the valve;
• monitoring, via the driving circuit based on a sense resistor associated with the valve, the voltage across the valve over a measurement interval, wherein the measurement interval terminates when the voltage reaches a predetermined threshold voltage;
• comparing the measurement interval to a reference interval for a normally functioning closed valve;
• and
• generating, based on the comparison, information indicative of whether the valve is closed.

A medical fluid system comprising:

• a valve configured to control a fluid flow in the medical fluid system, wherein the valve comprises a housing, a solenoid coil, and a plunger, and wherein the valve is configured to activate a flow of fluid by applying a voltage to the solenoid coil to move the plunger within the housing;
• a driving circuit configured to control the valve of the medical fluid system via pulse width modulation (PWM) signals, in response to control signals;
• and
• a microcontroller comprising a processor and a memory, wherein the memory stores instructions that, when executed by the processor, cause the processor to:
• transmit a control signal for closing the valve, wherein the valve is open at least before the control signal is transmitted,
• apply, via the driving circuit, power to the valve to measure a voltage across the valve,
• monitor, via the driving circuit based on a sense resistor associated with the valve, the voltage across the valve over a measurement interval, wherein the measurement interval terminates when the voltage reaches a predetermined threshold voltage,
• compare the measurement interval to a reference interval for a normally functioning closed valve, and
• generate, based on the comparison, information indicative of whether the valve is closed.