Split-phase Machines Research Articles

Parallel Operation of Integrated Battery Chargers for All Wheel Drive Electric Vehicles

In this paper, an integrated charging scheme for All Wheel Drive (AWD) Electric Vehicles (EVs) is proposed. The proposed scheme utilizes the existing driving hardware for charging the battery pack with minimum external components. As the driving hardware of AWD EVs include two motors and two inverters, an Integrated Battery Charger (IBC) with parallel configuration is proposed. In the existing topology of three phase IBC using split phase machine, the grid currents were not balanced. But in the proposed parallel IBC topology, the two split phase machines are proposed with different phase configurations, namely R-Y-B and Y-R-B, which will cancel the unbalance caused by each IBC, and make the grid currents balanced. The mathematical proof for the same is also included in this paper.The proposed parallel topology of IBCs has higher power rating and hence provides faster charging compared to conventional single IBCs. Circulating current mitigation for parallel IBCs is also presented in this paper. Exhaustive simulation and experimental results are included to validate the proposed scheme.

Modeling and Control of an Integrated Battery Charger With Split-Phase Machine

The battery charging technology is a rapidly developing area in the electric vehicle (EV) industry. The nonavailability of charging stations, longer battery charging times, and range-anxiety are main concerns for EV users. A fast, light, and efficient on-board charger is the need of the hour. Integrated battery chargers (IBC) are a viable solution since it uses the driving circuit (motor and inverter) already present in the EV for charging the battery. IBC using split-phase machine and three-legged inverter is an interesting topology. It has the advantage of using the existing three-phase machine and three-legged inverter. Also, this topology generates zero instantaneous torque while charging the battery. Due to motor winding reconfiguration during charging, even when the grid supply is balanced, the grid currents were found to be highly unbalanced. In this article, a mathematical model of the IBC using a split-phase machine in stationary and rotating reference frame is developed and presented for the first time. Mathematical proof for zero instantaneous torque production while charging the battery is presented. The effects of mutual inductance, $L_{dq}$ along with $L_d$ and $L_q$ , are presented in the rotating reference frame model of the IBC. This is found to make the system unbalanced, and the grid currents represented the in rotating reference frame are found to contain second harmonic components along with the expected dc terms. Using the mathematical model, new feedforward terms have been developed, and used in the control loop with proportional integral controller (PI) and proportional resonant controllers to mitigate grid current harmonics. Exhaustive simulation and experimental results are included for the proposed system.

Current regulator instabilities on parallel voltage-source inverters

Parallel inverters are often used to meet system power requirements beyond the capacity of the largest single structure. They have also been used to reduce harmonics, reduce pulsewidth modulation (PWM) switching frequency and increase available output voltage or frequency. The type of parallel structure depends on the construction of the load motor; the most prevalent are dual three-phase machines, split-phase machines, six-phase machines, and a standard three-phase machine with interphase reactors. Operation of parallel structures presents areas for investigation encompassing analysis, simulation, control, and design. This paper reports on the commissioning of a 775 HP dual-winding three-phase motor with parallel inverters. A simple method of paralleling structures with carrier-based PWM current regulators to independently regulate each inverter's current is employed. Experimental results show a loss of current control that is similar to a random event. The instability between the parallel inverters and the common motor can result in large uncontrolled currents. Simulations established that the reduction in controller gain, as the regulator enters the PWM pulse-dropping or overmodulation region, results in a loss of current control. Experimental results show the loss of current control is the result of an interaction between the parallel inverters through the dual-wound three-phase motor. Modifications were made to the modulator and a two-phase discontinuous controller was employed; the gain characteristic of the two-phase modulator in the overmodulation region extends the dynamic range of the motor drive.

Vector Control of Induction Motor with Split Phase Windings

A vector controlled scheme is described for an induction motor with split phase windings. Such a motor is obtained by splitting the phase windings of a conventional three phase motor with an angular separation of 30 electrical degrees between the axes of the two halves. In the proposed scheme the motor is run as a three phase machine by connecting the split phase windings in series. An appropriate split phase induction motor model based on space phasor notations is proposed. From this space phasor model of the split phase machine, a simple technique for measuring the equivalent circuit parameters for the motor is presented. Based on the proposed model a method for acquiring the position of the rotor flux is developed. The scheme is based only on the voltage and current measurements, without the need for position encoders. It is also independent of machine resistance values. Results from computer simulation as well as from an experimental prototype drive are presented and discussed.

Split-phase induction motor operation from PWM voltage source inverter

The operation of split-phase induction motors from pulse-width modulated (PWM) voltage source inverters is examined. Splitting the phase windings leads to reduced voltage ratings for the inverter switches. As compared with seven positions for the space phasor of voltage in three-phase machines, 48 different locations bounded by a 12-sided polygon are possible in the split-phase machine. Based on space phasor modulation, a three-phase inverter can give a maximum peak fundamental of 0.577 V/sub DC/. In comparison, the split-phase configuration can provide an equivalent three-phase maximum peak fundamental of 0.643 V/sub DC/ with a DC bus voltage of 0.5 V/sub DC//cos 15.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>