This paper presents a control concept for a drive system consisting of a 9-phase PMSM connected to a stacked polyphase bridge converter (SPBC) under consideration of the DC source impedance (R b ,L b ). When the converter is connected to the DC source with a cable, the cable impedance represents a source impedance that could cause instabilities affecting the total DC link voltage and the module voltage balance. In this paper, a control concept is presented for stabilising the module voltage balance via an appropriate definition of the module reference voltage. The total DC link voltage is not controlled but stability is ensured by sufficiently large DC link capacitors. The complete drive controller concept is validated in a simulation of a 1.5kW drive system.

In this paper, a new design procedure for the optimal design of an integrated motor drive is presented, including an extended iron loss model. The design procedure is based on a multi-objective optimization of power density, efficiency, and cost. In the optimization, a large design space is covered, including the inverter topology, the PWM scheme, the chip technology (Si/SiC/GaN), the winding scheme, the chip area/cost, and the switching frequency. In addition to power density/efficiency/cost, the system reliability is investigated. Considering a 1.5 kW IMD as example, the optimal design in terms of efficiency and cost is achieved using a modular topology, GaN HEMTs, and a 9-phase motor winding. This design enables an efficiency increase of +2.26 % at 36 % higher cost compared to the cost-optimal design that is achieved with the standard 2L-topology, Si IGBTs, and a 3-phase motor winding.

In this paper, the achievable cooling limits of passively cooled integrated motor drives are investigated. For the concept of a drive-integrated end cap with cooling fins a thermal model is derived and used to calculate the cooling system performance index, resulting in a range of CSPI = 0.67..1.8WK−1 L−1 which is primarily suitable for high-torque, low-speed motors.

Stacked Polyphase Bridge Converters (SPB-C) are well suited for integrated motor drives, i.e. for systems that combine an electric motor with its supplying power electronic converter in one compact unit. A SPB-C requires a motor with multiple 3-phase winding systems. In the literature, the SPB-C is typically combined with motors whose winding systems are phase-aligned. This type of winding is magnetically equivalent to a 3-phase winding (with parallel branches). In this paper, the SPB-C with either 2, 3, or 4 modules is combined with a motor that has non-phase-aligned winding systems what results in a 6-, a 9-, or a 12-phase system, respectively. These multiphase systems are compared to 3-phase systems with the same number of modules with regard to efficiency, power density, and the possible degree of modularity and the benefits of the multiphase systems are evaluated.