Portable controller with integral power source for mechanical circulation support systems
View Patent ↗A portable external device for a mechanical circulation support system includes first and second power sources, e.g. batteries and control electronics for redundant uninterrupted operation of an implantable blood pump. The control and power source module may be configured to accommodate a variety of wearable configurations for patient convenience and comfort.
1. A portable external device for a mechanical circulation support (MCS) system comprising:
a power source configured to power an implantable pump;
digital memory storing an algorithm for controlling an electric motor configured to drive the implantable pump; and
control electronics configured to control the electric motor employing the algorithm,
wherein the algorithm comprises instructions for causing the control electronics to:
control the electric motor according to a field-oriented control (FOC) algorithm stored within the digital memory;
while controlling the electric motor according to the FOC algorithm, estimate a back electromotive force (EMF) of the electric motor;
determine a rotational position of a rotor of the electric motor based on the estimated back EMF of the electric motor;
determine a pulse width modulated (PWM) voltage signal to send from the power source to the electric motor to drive the implantable pump based on the rotational position of the rotor of the electric motor;
determine an error of the estimated back EMF;
compare the error of the estimated back EMF to a threshold; and
control the electric motor employing a trapezoidal control algorithm stored on the digital memory if the error of the estimated back EMF is greater than the threshold.
2. The device of claim 1 , wherein the instructions of the algorithm for causing the control electronics to estimate the estimated back EMF of the electric motor comprises instructions for causing the control electronics to:
sense current from the electric motor; and
estimate the back EMF of the electric motor based on the current from the electric motor.
3. The device of claim 2 , wherein the instructions of the algorithm for causing the control electronics to determine the rotational position of the rotor of the electric motor based on the estimated back EMF comprises instructions for causing the control electronics to:
map a plurality of currents from a plurality of phases of the electric motor to one or more current vectors on a stationary, time dependent, two-axis coordinate system using a Clarke transformation;
map the one or more current vectors on the stationary, time dependent, two-axis coordinate system to a rotating, time-independent, two-axis coordinate system using a Park transformation; and
determine the rotational position of the rotor of the electric motor based on the estimated back EMF and the one or more current vectors on the rotating, time-independent, two-axis coordinate system.
4. The device of claim 1 , wherein the instructions of the algorithm for causing the control electronics to determine the error of the estimated back EMF comprises instructions for causing the control electronics to:
generate a mathematical model of the electric motor based on one or more parameters of the electric motor determined by the control electronics;
determine a modeled back EMF based on the mathematical model of the electric motor; and
compare the modeled back EMF to the estimated back EMF to determine the error of the estimated back EMF.
5. The device of claim 4 , wherein the mathematical model of the electric motor comprises at least one of a sliding mode or a luenberger observer.
6. The device of claim 1 , wherein the algorithm comprises instructions for causing the control electronics to:
sense a rotational position of a rotor of the electric motor; and
determine a PWM voltage signal to send from the power source to the electric motor to drive the implantable pump based on the rotational position of the rotor of the electric motor.
7. The device of claim 6 , wherein the control electronics senses the rotational position of the rotor of the electric motor using at least one hall sensor.
8. The device of claim 1 , wherein the control electronics comprises at least one shunt configured to sense current from at least one phase of the electric motor.
9. The device of claim 8 , wherein the control electronics comprises three shunts configured to sense current from three phases of the electric motor, respectively.
10. The device of claim 1 , wherein the control electronics comprises at least one pair of Field Effect Transistors (FET) configured to generate a PWM voltage signal to be sent from the power source to the electric motor to drive the implantable pump.
11. A mechanical circulation support (MCS) system comprising:
an implantable pump; and
a portable external device comprising:
a power source configured to power an implantable pump;
digital memory storing an algorithm for controlling an electric motor configured to drive the implantable pump; and
control electronics configured to control the electric motor employing the algorithm,
wherein the algorithm comprises instructions for causing the control electronics to:
control the electric motor according to a field-oriented control (FOC) algorithm stored within the digital memory;
while controlling the electric motor according to the FOC algorithm, estimate a back electromotive force (EMF) of the electric motor;
determine a rotational position of a rotor of the electric motor based on the estimated back EMF of the electric motor;
determine a pulse width modulated (PWM) voltage signal to send from the power source to the electric motor to drive the implantable pump based on the rotational position of the rotor of the electric motor;
determine an error of the estimated back EMF;
compare the error of the estimated back EMF to a threshold; and
control the electric motor employing a trapezoidal control algorithm stored on the digital memory if the error of the estimated back EMF is greater than the threshold.
12. The system of claim 11 , wherein the instructions of the algorithm for causing the control electronics to estimate the estimated back EMF of the electric motor comprises instructions for causing the control electronics to:
sense current from the electric motor; and
estimate the back EMF of the electric motor based on the current from the electric motor.
13. The system of claim 12 , wherein the instructions of the algorithm for causing the control electronics to determine the rotational position of the rotor of the electric motor based on the estimated back EMF comprises instructions for causing the control electronics to:
map a plurality of currents from a plurality of phases of the electric motor to one or more current vectors on a stationary, time dependent, two-axis coordinate system using a Clarke transformation;
map the one or more current vectors on the stationary, time dependent, two-axis coordinate system to a rotating, time-independent, two-axis coordinate system using a Park transformation; and
determine the rotational position of the rotor of the electric motor based on the estimated back EMF and the one or more current vectors on the rotating, time-independent, two-axis coordinate system.
14. The system of claim 11 , wherein the instructions of the algorithm for causing the control electronics to determine the error of the estimated back EMF comprises instructions for causing the control electronics to:
generate a mathematical model of the electric motor based on one or more parameters of the electric motor determined by the control electronics;
determine a modeled back EMF based on the mathematical model of the electric motor; and
compare the modeled back EMF to the estimated back EMF to determine the error of the estimated back EMF.
15. The system of claim 14 , wherein the mathematical model of the electric motor comprises at least one of a sliding mode or a luenberger observer.
16. The system of claim 11 , wherein the algorithm comprises instructions for causing the control electronics to:
sense a rotational position of a rotor of the electric motor; and
determine a PWM voltage signal to send from the power source to the electric motor to drive the implantable pump based on the rotational position of the rotor of the electric motor.
17. The system of claim 16 , wherein the control electronics senses the rotational position of the rotor of the electric motor using at least one hall sensor.
18. The system of claim 11 , wherein the control electronics comprises at least one shunt configured to sense current from at least one phase of the electric motor.
19. The system of claim 18 , wherein the control electronics comprises three shunts configured to sense current from three phases of the electric motor, respectively.
20. The system of claim 11 , wherein the control electronics comprises at least one pair of Field Effect Transistors (FET) configured to generate a PWM voltage signal to be sent from the power source to the electric motor to drive the implantable pump.