A document by Gwendolin Rohner . Click on the document to view its contents.

The ShuttlePump is a novel implantable total artificial heart (TAH) concept based on a Linear-Rotary Actuator (LiRA) and currently under development at the Power Electronic Systems Laboratory, ETH Zurich in close partnership with Charit´e Berlin and the Medical University of Vienna. This paper presents the analysis, design and realization of the ShuttlePump Linear Actuator (LA) part, which is necessary to provide about 45 N of axial actuation force. Design criteria are minimization of volume and generated power losses in the winding, which could result in excess heating and/or blood damage, i.e. protein denaturation and aggregation. The LA is implemented as a Tubular LA (TLA) to maximize the active area for linear/axial force generation. After a preliminary analysis based on first principles, the TLA is optimized in detail with the aid of FEM simulations. The experimental measurements conducted on the realized TLA prototype verify the FEM simulation results and confirm the suitability for the realization of the ShuttlePump TAH.

Objective: Total artificial hearts (TAH) are used as a temporary treatment for severe biventricular heart failure. Long-term cardiac replacement is hampered by limited durability and complication rates, which may be attributable to the modus operandi of state-of-the-art pumping systems. The aim of this study was to assess the feasibility of a novel valveless pumping principle for a durable pulsatile TAH (ShuttlePump). Methods: With a rotating and linearly shuttling piston within a cylindrical housing with 2 in- and outlets, the pump features only one single moving part and delivers pulsatile flow to both systemic and pulmonary circulation. The pump and actuation system were designed iteratively based on analytical and in silico methods, utilizing finite element methods (FEM) and computational fluid dynamics (CFD) Pump characteristics were evaluated experimentally in a mock circulation loop mimicking the cardiovascular system, while hemocompatibility related parameters were calculated numerically. Results: Pump characteristics cover the entire required operating range for a TAH (2.5 - 9L/min at 50 - 160mmHg arterial pressures) at stroke frequencies of 1.5 - 5Hz while balancing left and right atrial pressures. FEM analysis showed a mean overall copper losses of 8.84W, resulting in local blood temperature rise of < 2k. The CFD results of normalized index of hemolysis was 3.57 mg/100L and 95% of the pumps blood volume was exchanged after 1.42s. Conclusion: This study indicates feasibility of a novel pumping system for a TAH with numerical and experimental results substantiating further development of the ShuttlePump.

Universal high-power three-phase mains interfaces for electric vehicle (EV) charging must provide a wide output voltage range (e.g., 200V to 800V) and thus provide buck and boost capability. An advantageous realization combining a three-level (3-L) T-type (Vienna) boost-type PFC voltage-source rectifier (VSR) with a 3-L buck-type DC/DC converter stage is presented in this paper. For high output voltages (boost-mode), the VSR-stage operates with 3/3-PWM, i.e., continuous PWM of all three phases to regulate the output voltage while the DC/DC-stage remains clamped to avoid switching losses. For low output voltages (buck-mode), the DC/DC-stage advantageously controls the DC-link voltage according to a time-varying reference value, which allows to sinusoidally shape the currents of two mains phases, such that the VSR-stage can operate with 1/3-PWM (only one of the three bridge-legs operates with PWM at any given time) with reduced switching losses. This paper proposes a novel 2/3-PWM scheme for the output voltage transition region, where output voltages are between the buck-mode and the boost-mode. This enables loss-optimum operation (i.e., the minimum number of the VSR-stage bridge-legs operating with PWM, and with the minimum possible DC-link voltage) for any output voltage. Furthermore, this paper introduces a new synergetic control concept that ensures seamless transitions between the loss-optimum operating modes. A comprehensive experimental verification, including pre-compliance EMI measurements, using a 10-kW hardware demonstrator with a power density of 5.4kW/L, a peak efficiency of 98.8% at rated power and 560V output voltage, and >98% efficiency for all operating points with >400V output voltage and more than about 50% of rated power, confirms the theoretical analyses.

A common 400V dc bus for industrial motor drives advantageously allows the use of high-performance 600V power semiconductor technology in the inverter drive converter stages and to lower the rated power of the supplying rectifier system. Ideally, this supplying rectifier system features unity power factor operation, bidirectional power flow and nominal power operation in the three-phase and the single-phase grid. This paper introduces a novel bidirectional universal single-/three-phase-input unity power factor differential ac-dc converter suitable for the above mentioned requirements: The basic operating principle and conduction states of the proposed topology are derived and discussed in detail. Then, the main power component voltage and current stresses are determined and simulation results in PLECS are provided. The concept is verified by means of experimental measurements conducted in both three-phase and single-phase operation with a 6kW prototype system employing a switching frequency of 100 kHz and 1200V SiC power semiconductors.