In order to improve the reliability of cardiac pacemaker contact-less power supply technology, this paper proposes a novel application of wireless feedback voltage stabilizing technology to adjust heart disease patients with inner power supply filter circuit output voltage and current control method, to keep the output voltage stability, and to ensure that the super capacitor and cardiac pacemaker to get a stable power supply. To implement the real-time accurate voltage control with considering the primary and secondary side inductance coupling coefficient changes, the change of the external power supply voltage and load, it is necessary to test thee real-time and accurate output voltage and current value after rectifying filtering. Therefore, based on the chaotic control theory, we adopted method of phase diagram on the basis of the quick observation after rectifying filtering, so that the method of voltage and current could improve the detection time of the circuit. The phase diagram of proposed control method can be divided into 8 segments, and we got 7 zero-extreme points. When these zero-extreme points are detected, according to extreme points of the zero instantaneous values, the corresponding average values of voltage and current were obtained. Simulation and experimental results showed that using the above method can shorten the response time to less than switch devices 1/2 switching cycles, thus validating the effectiveness and feasibility of the proposed detection algorithm.
We propose a control model of the cardiovascular system coupled with a rotary blood pump in the present paper. A new mathematical model of the rotary heart pump is presented considering the hydraulic characteristics and the similarity principle of pumps. A seven-order nonlinear spatial state equation adopting lumped parameter is used to describe the combined cardiovascular-pump model. Pump speed is used as the control variable. To achieve sufficient perfusion and to avoid suction, a feedback strategy based on minimum (diastolic) pump flow is used in the control model. The results showed that left ventricular assist device (LVAD) could improve hemodynamics of the cardiovascular system of the patient with heart failure in open loop. When rotation speed was 9,000 r/min, cardiac output reached 82 mL/s while the initial cardiac output was only 34 mL/s without the LVAD support. When the rotation speed was above 12 800 r/min, suction was found because the high rotating speed resulted in insufficient venous return volume. Suction was avoided by adopting the feedback control. The model reveals the interaction of LVAD and the cardiovascular system, which provides theoretical basis for the therapy of heart failure in the left ventricular and for the design of a physiological control strategy.
The subpulmonary ventricular exclusion (Fontan) could effectively improve the living quality for the children patients with a functional single ventricle in clinical. However, postoperative Fontan circulation failure can easily occur, causing obvious limitations while clinically implementing Fontan. The cavopulmonary assist devices (CPAD) is currently an effective means to solve such limitations. Therefore, in this paper the in-silico and in-vitro experiment coupled model of Fontan circulation failure for the children patients with a single ventricle and CPAD is established to evaluate the effects of CPAD on the Fontan circulation failure. Then a sensorless feedback control algorithm is proposed to provide sufficient cardiac output and prevent vena caval suction due to CPAD constant pump speed. Based on the CPAD pump speed-an intrinsic parameter, the sensorless feedback control algorithm could accurately estimate the cavopulmonary pressure head (CPPH) using extended Kalman filter, eliminating the disadvantage for pressure sensors that cannot be used in long term. And a gain-scheduled, proportional integral (PI) controller is used to make the actual CPPH approach to the reference value. Results show that the CPAD could effectively increase physiological perfusion for the children patients and reduce the workload of a single ventricle, and the sensorless feedback control algorithm can effectively guarantee cardiac output and prevent suction. This study can provide theoretical basis and technical support for the design and optimization of CPAD, and has potential clinical application value.