In the present invention, in an electromagnetic device that uses a coil current, such as a motor, an initial value of a desired coil current waveform is inputted, a magnetic field analysis is performed for the electromagnetic device, a power supply voltage waveform which is derived from a magnetic vector potential acquired from the analysis is calculated, and a circuit coupled magnetic field analysis is performed by using a fundamental waveform component of the calculated power supply voltage waveform, thereby providing a power supply voltage waveform calculation method and a circuit coupled magnetic field analysis method for obtaining a steady solution more quickly than in the conventional technique.

A ripple detection device 10 includes: a current detection part 11 that outputs a variation in an armature current as a voltage variation signal; a first smoothing circuit block 12 that extracts a current ripple component and a noise component from the voltage variation signal and outputs a first smoothing signal S1; a gain adjustment part 13 that adjusts the amplitude of the first smoothing signal S1 and outputs an adjustment signal VCA; a second smoothing circuit block 14 that corrects distortion of the adjustment signal VCA and outputs a second smoothing signal S2; a ripple detection part 15 that extracts only the current ripple component from the second smoothing signal S2 by removing the noise component therefrom and outputs a ripple component signal S0; and a digital signal conversion part 16 that converts the ripple component signal S0 into a digital signal.

A controller of a rotating electric machine includes a current detector detecting a voltage of each of shunt resistors in at least two phases from among the shunt resistors in three phases during an electric current flowing period in which the shunt resistors in the at least two phases have an electric current flowing therein; and a signal generator setting a switching mode of each of switches forming an inverter for controlling an estimated angular velocity to an instruction angular velocity based on the detected voltage. The signal generator sets a switching mode to flow the electric current in the shunt resistors in the at least two phases during at least part of one half of a modulation cycle of control of the estimated angular velocity.

A system according to the present disclosure includes a motor driver module and a motor position determination module. The motor driver module is configured to measure current supplied to a motor. The motor position determination module is configured to determine a first position of the motor at a first time when power supply to the motor is initially discontinued based on ripples in the current supplied to the motor during a first period before the first time. The motor position determination module is configured to determine a second position of the motor at a second time when the motor stops rotating after power supply to the motor is discontinued based on the first position of the motor and a rotational speed of the motor at the first time.

In an example, a system is disclosed. The system includes a rotor position estimation module configured to generate an adjustment signal to adjust a desired torque signal for a motor. The rotor position estimation module includes a sensor offset estimation module configured to estimate an offset position of a sensor based on (1) a motor current signal indicative of a current to rotate a rotor within the motor, (2) a motor voltage signal indicative of a voltage applied to a power inverter that provides the current to the motor, and (3) a motor parameter. The sensor can be disposed on the rotor. The rotor position estimation module also includes a speed adjustment module configured to generate the adjustment signal based on the estimated offset position.

A motor driving device includes an OPEN driving mode in which a driving waveform is generated without using detection information of a rotational position of a rotor and the rotor is rotated, and a CLOSE driving mode in which a phase of a rotational position and a phase of a driving waveform are synchronized using the detection information of the rotational position of the rotor, a desired phase difference is set between the rotational position and the driving waveform, and the rotor is rotated. The CPU controls rotation of the rotor using the OPEN driving mode, instructs a driving waveform generating circuit to set a phase difference for generating a torque in a reversing direction when rotation of the rotor is reversed, switches to the CLOSE driving mode, and then switches to the OPEN driving mode again when reversing has been completed.

A ripple detection device 10 includes: a current detection part 11 that outputs a variation in an armature current as a voltage variation signal; a first smoothing circuit block 12 that extracts a current ripple component and a noise component from the voltage variation signal and outputs a first smoothing signal S1; a gain adjustment part 13 that adjusts the amplitude of the first smoothing signal S1 and outputs an adjustment signal VCA; a second smoothing circuit block 14 that corrects distortion of the adjustment signal VCA and outputs a second smoothing signal S2; a ripple detection part 15 that extracts only the current ripple component from the second smoothing signal S2 by removing the noise component therefrom and outputs a ripple component signal S0; and a digital signal conversion part 16 that converts the ripple component signal S0 into a digital signal.

A system according to the present disclosure includes a motor driver module and a motor position determination module. The motor driver module is configured to measure current supplied to a motor. The motor position determination module is configured to determine a first position of the motor at a first time when power supply to the motor is initially discontinued based on ripples in the current supplied to the motor during a first period before the first time. The motor position determination module is configured to determine a second position of the motor at a second time when the motor stops rotating after power supply to the motor is discontinued based on the first position of the motor and a rotational speed of the motor at the first time.

An electric vehicle propulsion control device includes a power converter that applies an alternating-current voltage to an induction machine and a controller that controls the power converter based on an external operation command. The controller includes a first calculation unit. The first calculation unit calculates, from current information (id and iq) detected at the induction machine and current command values (id*1 and iq*1) that are based on the operation command, a d-axis voltage command (Vd*1) and a q-axis voltage command (Vq*1) for the power converter, and a primary magnetic flux ds and a secondary magnetic flux dr of the induction machine. The first calculation unit also adds to or subtracts from a term including the q-axis voltage command (Vq*1) an interference term stemming from the d-axis voltage command (Vd*1) in calculating a first speed 1 that is a free-run speed of the induction machine.

A system, method, and computer-readable medium for determining the flow rate and fluid density in an electrical submersible pump (ESP) and controlling the ESP based on the flow rate and density. In one implementation, an ESP system includes an ESP, drive circuitry, a current sensor, a voltage sensor, and a processor. The ESP includes an electric motor. The drive circuitry is electrically coupled to the ESP and is configured to provide an electrical signal to power the ESP. The current sensor is configured to measure a current of the electrical signal. The voltage sensor is configured to measure a voltage of the electrical signal. The processor is configured to calculate speed of a shaft of the electric motor based on a frequency induced by rotation of the motor detected in the current. The processor is also configured to calculate a density of fluid in the ESP based on the speed.