To surely detect a back electromotive force generated in a non-conduction phase at an extremely low duty ratio, a motor driving system includes a three-phase motor, an inverter circuit, and a semiconductor device. A controller included in the semiconductor device compares a voltage at an output node corresponding to a non-conduction phase of the inverter circuit and a reference voltage with each other, thereby estimating a position of a rotor of the three-phase motor and generating a pulse width modulation signal based on the estimated position of the rotor. The controller detects the voltage at the output node of the non-conduction phase in a regeneration period of the pulse width modulation signal when a duty ratio of the pulse width modulation signal is less than a threshold value, the regeneration period being a period in which current is made to flow to the three-phase motor on a regeneration path.

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 motor driver device supplies drive voltages to three phase coils of a stator in a brushless DC motor based on a detection result of a position of a rotor in a sensorless manner. In a position detection section, two phase coils are set as a target coil pair and a remaining one phase coil is set as a non-target coil, and with respect to all combinations of target coil pairs, a first process of applying a pulse voltage from a first direction to the target coil pair and a second process of applying a pulse voltage from a second direction opposite to the first direction to the target coil pair are executed. In the first and second processes, power supply to the non-target coil is stopped. The position of the rotor is detected based on voltages generated in the non-target coil in each first process and each second process.

A method of and system for controlling a DC midpoint of a multi-level inverter. The method includes receiving an input power signal from an AC power source at a multi-level motor control system that includes a DC bus and a multi-level inverter configured to supply a load, the DC bus having a DC midpoint, connecting a DC midpoint of a DC bus to a neutral point of the AC power source, while isolating a neutral point of a load supplied by the multi-level inverter from the DC midpoint, monitoring a voltage on the DC midpoint of the DC bus. In addition, the method may include controlling a voltage of the neutral point of the AC load based on imbalances in the load supplied by the multi-level inverter.

A starting power generation apparatus according to an embodiment of the present invention includes: a starter generator including a field portion having a permanent magnet, and an armature unit including a first multi-phase winding and a second multi-phase winding which are arranged in parallel; a first power conversion unit including a first positive-side DC terminal connected to a battery and a plurality of first AC terminals connected to the first multi-phase winding, the first power conversion unit being configured to convert a power bidirectionally between DC and AC; a second power conversion unit including a plurality of second AC terminals connected to the second multi-phase winding, the second power conversion unit being configured to control a current to be input and output via the second AC terminals; and a control unit configured to detect a positional relationship between the field portion and the armature unit based on an output voltage of the second multi-phase winding, and control the first power conversion unit and the second power conversion unit in accordance with the positional relationship detected. The control unit is configured to detect the positional relationship when the starter generator is stopped, based on time widths of two or more predetermined voltages generated in two or more windings constituting the second multi-phase winding in a case that an output voltage of the battery is applied to the first multi-phase winding for a predetermined time in a state where current input and output via the second AC terminals is off.

A method for determining the position of the rotor of a multiphase electric machine with pole windings, the inductances of which are uniquely connected to the rotational angular position of the rotor in the currentless state at least within rotational angular periods. At least one measurement point between pole windings, a measurement signal which depends on the current inductances of the pole windings and which is generated by voltage jumps at a phase conductor input is tapped. Multiple measurement points are provided for tapping a signal, the measurement points being arranged collectively at one and the same phase conductor. For each measurement point, the respective phase conductor with the lowest current operating current is selected.

A method of and system for controlling a DC midpoint of a multi-level inverter. The method includes receiving an input power signal from an AC power source at a multi-level motor control system that includes a DC bus and a multi-level inverter configured to supply a load, the DC bus having a DC midpoint, connecting a DC midpoint of a DC bus to a neutral point of the AC power source, while isolating a neutral point of a load supplied by the multi-level inverter from the DC midpoint, monitoring a voltage on the DC midpoint of the DC bus. In addition, the method may include controlling a voltage of the neutral point of the AC load based on imbalances in the load supplied by the multi-level inverter.

A device and control method for driving a sensorless brushless DC (BLDC) motor, particularly related to a technology configured to increase the accuracy of detection of Zero Cross Point through a non-commutation period in a pulse width modulation (PWM) control. The device for driving a sensorless BLDC motor to switch a current applied to a stator winding based on a position of a rotor includes a three phase inverter configured to convert a DC input voltage into a three phase AC voltage and supply the three phase AC voltage to the BLDC motor; a terminal voltage detector configured to detect a three phase terminal voltage from an output terminal of the three phase inverter; and a controller configured to perform a PWM control of the terminal voltage based on a three phase back electromotive force (EMF) included in the detected terminal voltage. The PWM control includes a non-commutation control in which the switching of the current does not occur.

To surely detect a back electromotive force generated in a non-conduction phase at an extremely low duty ratio, a motor driving system includes a three-phase motor, an inverter circuit, and a semiconductor device. A controller included in the semiconductor device compares a voltage at an output node corresponding to a non-conduction phase of the inverter circuit and a reference voltage with each other, thereby estimating a position of a rotor of the three-phase motor and generating a pulse width modulation signal based on the estimated position of the rotor. The controller detects the voltage at the output node of the non-conduction phase in a regeneration period of the pulse width modulation signal when a duty ratio of the pulse width modulation signal is less than a threshold value, the regeneration period being a period in which current is made to flow to the three-phase motor on a regeneration path.

A starting power generation apparatus according to an embodiment of the present invention includes: a starter generator including a field portion having a permanent magnet, and an armature unit including a first multi-phase winding and a second multi-phase winding which are arranged in parallel; a first power conversion unit including a first positive-side DC terminal connected to a battery and a plurality of first AC terminals connected to the first multi-phase winding, the first power conversion unit being configured to convert a power bidirectionally between DC and AC; a second power conversion unit including a plurality of second AC terminals connected to the second multi-phase winding, the second power conversion unit being configured to control a current to be input and output via the second AC terminals; and a control unit configured to detect a positional relationship between the field portion and the armature unit based on an output voltage of the second multi-phase winding, and control the first power conversion unit and the second power conversion unit in accordance with the positional relationship detected. The control unit is configured to detect the positional relationship when the starter generator is stopped, based on time widths of two or more predetermined voltages generated in two or more windings constituting the second multi-phase winding in a case that an output voltage of the battery is applied to the first multi-phase winding for a predetermined time in a state where current input and output via the second AC terminals is off.