An apparatus includes an integrated circuit (IC). The IC includes a differencing comparator. The differencing comparator receives a differential input signal. The differencing comparator compares the differential input signal to a threshold value. The differencing comparator includes a transconductance circuit coupled to receive the differential input signal and to provide a differential output signal.

A controller includes a torque command value calculation module configured to calculate a torque command based on a speed command of the motor, an output voltage controlling module configured to control an output voltage of the power converter based on the torque command calculated by the torque command value calculation module, a voltage command value correcting module configured to correct a voltage command to the power converter based on a measured output voltage from the power converter, a flux estimation module configured to estimate stator flux and rotor flux of the motor in a subsequent control period based on the voltage command by the voltage command value correcting module and a measured current of the stator and a motor speed estimation module configured to estimate a speed of the motor in a subsequent control period based on the flux estimated by the flux estimation module.

A controller includes a torque command value calculation module configured to calculate a torque command based on a speed command of the motor, an output voltage controlling module configured to control an output voltage of the power converter based on the torque command calculated by the torque command value calculation module, a voltage command value correcting module configured to correct a voltage command to the power converter based on a measured output voltage from the power converter, a flux estimation module configured to estimate stator flux and rotor flux of the motor in a subsequent control period based on the voltage command by the voltage command value correcting module and a measured current of the stator and a motor speed estimation module configured to estimate a speed of the motor in a subsequent control period based on the flux estimated by the flux estimation module.

A method for reducing lower order harmonics of a power converter includes, for each phase leg of the converter: obtaining a voltage reference for the phase leg; for a present sample, obtaining a flux error of the output voltage of the leg; dividing the first sample flux error by a time period to obtain an average voltage error over said time period; subtracting an obtained processed average voltage error, based on the average voltage error, from the voltage reference to obtain a modified voltage reference for the phase leg; and providing the modified voltage reference to a modulation unit of the converter for controlling the phase leg.

A powertrain for a vehicle includes a wye wound electric machine and a controller. The electric machine is coupled with an inverter. The controller is configured to, in response to an electrical connection between the vehicle and an AC grid, couple a capacitor between a neutral terminal of the electric machine and a negative terminal of the inverter to absorb reactive power from the AC grid.

A control device of a synchronous electric motor includes: the synchronous electric motor with three-phase stator windings Y-connected; a detection unit that detects a neutral point potential which is a potential at a Y connection point; and an inverter that drives the synchronous electric motor. The control device of the synchronous electric motor which controls the synchronous electric motor using the inverter, includes a measurement mode in which the neutral point potential is detected in a state in which the synchronous electric motor is energized by an AC current and controls the synchronous electric motor based on a value of the neutral point potential detected in the measurement mode.

A powertrain for a vehicle includes a wye wound electric machine and a controller. The electric machine is coupled with an inverter. The controller is configured to, in response to an electrical connection between the vehicle and an AC grid, couple a capacitor between a neutral terminal of the electric machine and a negative terminal of the inverter to absorb reactive power from the AC grid.

A method for detecting a potential (Vn) includes stator wirings in a Y connection, and automatically adjusting a relationship with a position of a rotor as a system for realizing rotor position-sensorless stable drive of an AC motor where the three-phase stator wirings are in Y connection in the stop and low-speed ranges. A synchronous motor control apparatus includes a three-phase synchronous motor in which three-phase stator wirings are in a Y connection, and an inverter for driving the motor, wherein the synchronous motor is DC-conducted thereby to move a rotor to a predetermined position, and is applied with a pulse-shaped voltage from the inverter in the moved state so that a neutral point potential as potential (Vn) of the Y connection point is acquired when the pulse voltage is applied, thereby driving the synchronous motor based on the acquired value.

In accordance with an embodiment, a sensor-less detection circuit is provided that includes a first voltage adjustment circuit coupled for receiving an induced voltage and a second voltage adjustment circuit coupled for receiving a common voltage. A differential amplifier has an inverting input terminal coupled to the first voltage adjustment circuit and a noninverting input terminal coupled to the second voltage adjustment circuit. In accordance with another embodiment, a method for detecting a motor rotor position is provided that includes receiving a first back electromotive force that is at a first voltage level and shifting the first back electromotive force from the first voltage level to a second voltage level. The first back electromotive force is filtered to generate a first filtered voltage; and a first motor rotor position signal is generated in response to comparing the first filtered voltage with a reference voltage.

A method for reducing lower order harmonics of a power converter includes, for each phase leg of the converter: obtaining a voltage reference for the phase leg; for a present sample, obtaining a flux error of the output voltage of the leg; dividing the first sample flux error by a time period to obtain an average voltage error over said time period; subtracting an obtained processed average voltage error, based on the average voltage error, from the voltage reference to obtain a modified voltage reference for the phase leg; and providing the modified voltage reference to a modulation unit of the converter for controlling the phase leg.