A motor drive method is a method of driving a motor by a motor drive apparatus. The motor drive apparatus includes an inverter that regulates supply power to the motor that is a synchronous machine and includes a controller that controls the inverter. The method includes changing, before loss of synchronism, a speed of the motor from a second speed range to a first speed range. A speed range in which the motor is operable at a substantially fixed speed is the first speed range, and a speed range that is lower than the first speed range and includes zero speed is the second speed range.

A motor drive method is a method of driving a motor by a motor drive apparatus. The motor drive apparatus includes an inverter that regulates supply power to the motor that is a synchronous machine and includes a controller that controls the inverter. The method includes changing, before loss of synchronism, a speed of the motor from a second speed range to a first speed range. A speed range in which the motor is operable at a substantially fixed speed is the first speed range, and a speed range that is lower than the first speed range and includes zero speed is the second speed range.

In the position sensorless control method in low-speed region of the fault-tolerant permanent magnet motor system based on the envelope detection and the non-orthogonal phase-locked loop of the present disclosure, the position sensorless control of the motor is implemented by injecting the high-frequency voltage signals into any two non-faulty phase windings of the motor, extracting the high-frequency response currents of the high-frequency injected phases by the digital bandpass filter, calculating the differential mode inductances of the two phase windings through the envelope detecting and signal processing, and extracting the rotor position and rotational speed signals from the estimated two phase inductances through the non-orthogonal phase-locked loop. In addition, the controller of the present disclosure is small in size, high in accuracy, and high in reliability, which can effectively meet the performance requirements of the onboard electric actuators.

In an electric power steering device assisted by a brushless motor, an induced voltage from a brushless motor is detected when a main power supply is off. The motor is determined to be in a high rpm state when the induced voltage is in a first transient state from a voltage ≦a high rpm detection threshold Th1 to a voltage≧Th1, thereby setting an intermittent excitation cycle of a revolution angle sensor connected to the motor to a short cycle. The motor is determined to be in a low rpm state when the induced voltage becomes a voltage≧a high rpm detection threshold Th2 after a wait period corresponding to an electrical angle between peaks or valleys of an output voltage has elapsed in a second transient state from a voltage–Th1 to a voltage≧Th2, thereby setting the cycle to a long cycle.

A position estimation device acquires detection values of magnetic field strength at three or more locations of a rotor in a range where a rotor angle is less than one rotation. A section is selected based on a detection value of the magnetic field strength from predetermined sections for a pole pair number of the rotor. A feature amount calculator is provided to calculate feature amounts of a waveform of the magnetic field strength based on a combination of the detection values of the magnetic field strength according to the section selected. An estimator is provided to determine, for each segment associated with the section selected, whether or not a magnitude relationship of the feature amounts learned in advance coincides with a magnitude relationship of the feature amounts calculated, and estimating, as a rotation position of the rotor, the pole pair number associated with the segment having the same magnitude relationship.

A variable speed drive comprises an output for delivering a drive voltage to an electric motor, power inverter, a drive controller, and a current sensor. The drive controller includes a PWM generator, a control law module, and a state variable estimator for estimating a state variable of the electric motor. The module computes a target voltage signal based on state variable estimates provided by the estimator and outputs the target voltage signal to the PWM generator. The generator approximates the target voltage signal with a PWM control signal, controls the inverter using the control signal, computes, based on the deviation between the control signal and the target voltage signal, an estimation support signal, and outputs the estimation support signal to the estimator. The estimator estimates a state variable of the motor based on the estimation support signal and the drive current, and outputs the estimate to the module.

A motor drive circuit comprises a motor having a plurality of phases, a switching circuit comprising a plurality of electrical switches, a motor current controller that generates voltage demand signals to be passed to a drive circuit for the switches that in turn generate pulse width modulated switching signals for the switching circuit that cause the switches to selectively connect the phases to a power supply so as to cause current to flow through the phases of the motor, and a motor torque controller that produces a demand signal that is fed to an input of the current controller, the motor current controller responding to an error signal that is at least partially dependent on the value of the demand signal. The torque controller in use updates the demand signal at a first sample rate. The motor drive circuit further comprises a downsampling circuit that in use modifies the demand signal under certain operating conditions so that the demand signal is only updated at a second sample rate that is lower than the first rate.

A motor drive circuit comprises a motor having a plurality of phases, a switching circuit comprising a plurality of electrical switches, a motor current controller that generates voltage demand signals to be passed to a drive circuit for the switches that in turn generate pulse width modulated switching signals for the switching circuit that cause the switches to selectively connect the phases to a power supply so as to cause current to flow through the phases of the motor, and a motor torque controller that produces a demand signal that is fed to an input of the current controller, the motor current controller responding to an error signal that is at least partially dependent on the value of the demand signal. The torque controller in use updates the demand signal at a first sample rate. The motor drive circuit further comprises a downsampling circuit that in use modifies the demand signal under certain operating conditions so that the demand signal is only updated at a second sample rate that is lower than the first rate.

An inverter controller is provided. The controller according to an exemplary embodiment of the present disclosure generates a compensation voltage to compensate an inverter command voltage using motor torque current and motor information, and apply the compensation voltage to the command voltage.

An inverter controller is provided. The controller according to an exemplary embodiment of the present disclosure generates a compensation voltage to compensate an inverter command voltage using motor torque current and motor information, and apply the compensation voltage to the command voltage.