Rockwell Automation Technologies Incorporated

Bing Li

Brian J Seibel

Takayoshi Matsuo

Jacob M Lamb

Lixiang Wei

Timothy M Rowan

Zhendong Zhang

Zhenyu Ye

A method for flying start control of a motor, a computer readable medium, and a power conversion system having an inverter and a controller configured by computer executable instructions in a memory to perform flying start of a rotating motor by field weakening control to control the motor responsive to the motor speed exceeding the rated speed or other non-zero threshold at startup of the power conversion system. The method includes measuring a motor speed of a motor, responsive to startup of a power conversion system, and performing a flying start operation using field weakening control to control the motor responsive to the motor speed exceeding a non-zero threshold at startup of the power conversion system.

Motor flying start using field weakening control

For improving Maximum Torque per Amps (MTPA) control, a method generates an offline MTPA curve based on an autotune test for a motor, which is used as offline MTPA control in order to run a motor at a high efficiency operation point. Another online method generates a search zone for the MTPA curve for a given torque point. The search zone includes an upper D-axis reference current and a lower D-axis reference current for the given torque point. The method iteratively modifies a D-axis reference current between the upper D-axis reference current and the lower D-axis reference current of the search zone. The method modifies a Q-axis reference current to output the given torque. The method updates a corresponding current pair of the given torque point to the modified D-axis reference current and the modified Q-axis reference current with a lowest current amplitude to improve MTPA control of the motor.

Efficiency optimization of maximum torque per amps control for synchronous motors

A power conversion system includes an inverter and a controller configured to: responsive to startup of the system, measure a motor speed of the IPM motor; responsive to the motor speed being less than a threshold, generate the inverter switching control signals to perform high frequency injection (HFI); during the HFI, determine a measured angle of the IPM motor; during the HFI, generate the inverter switching control signals to provide an injected current to the IPM motor; detect acceleration or deceleration of the IPM motor responsive to the injected current; selectively determine an electrical angle as half the measured angle or as 180 degrees plus half the measured angle based on the detected acceleration or deceleration of the IPM motor; and responsive to determining the electrical angle, generate the inverter switching control signals to drive the IPM motor to a reference frequency in a normal operating mode of the inverter.

IPM motor flying start using high frequency injection

For motor stator resistance calculation, a method estimates an output voltage using a Direct Current (DC) bus voltage and a duty ratio for a motor drive at a first switching frequency and at least one second switching frequency. The method measures an output current at the first switching frequency and the at least one second switching frequency. The method calculates a first stator resistance for the first switching frequency and at least one second stator resistance for the at least one second switching frequency. The method estimates a stator resistance at a DC condition based on the first stator resistance and the at least one second stator resistance. The method sets a dynamic compensation based on a stator resistance error between the first switching frequency and the at least one second switching frequency.

Motor stator resistance calculation

For flux map identification, a method applies an initial voltage to a motor. The motor is a salient motor. The method generates a flux map for the motor. The method iteratively applies a variable voltage to the motor. The variable voltage includes a constant current change calculated from the flux map. The method iteratively modifies the flux map.

Iterative flux identification

For encoder offset fine tuning, a processor iteratively reduces an encoder offset error of the motor with a third offset step until the motor starts. The processor iteratively modifies the encoder offset of the motor turning in a positive direction with a first offset step until the motor stops. The processor further records the encoder offset as a first encoder offset. The processor iteratively modifies the encoder offset with the first offset step until the motor starts turning in a negative direction. The negative direction is opposite the positive direction. The processor iteratively modifies the encoder offset with a second offset step until the motor stops. The processor records the encoder offset as a second encoder offset. In addition, the processor calculates a final encoder offset as a function of the first encoder offset and the second encoder offset.

Encoder offset fine tuning

For counter electromotive force estimation, a disturbance estimator calculates an estimated disturbance as a control function of a quadrature axis current regulator output signal and a quadrature axis current feedback signal of a running permanent magnet motor. A calculator calculates an estimated counter electromotive force of the running permanent magnet motor as a function of the estimated disturbance, a control flux, and an angular velocity.

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Mequon, WI, United States of America

Bing Li