State estimation device, drive system, refrigeration system, fan system, and state estimation method

A state estimation device for estimating a state of a device in which a motor is mounted, the state estimation device comprising:

• a control unit,
• the control unit being configured to perform
• an estimation process for estimating the state of the device, based on a magnitude of a specific frequency component of a physical quantity obtained from the device, and
• a restriction process for restricting the estimation process or an operation of the motor, based on a magnitude of a periodic component included in a variable calculated based on the magnitude of the specific frequency component, wherein
• the restriction process is a first restriction process for restricting the estimation process so that a predetermined estimation result is output, or a second restriction process for restricting the operation of the motor so that no erroneous estimation is performed in the estimation process.

A state estimation method for estimating a state of a device in which a motor driven by an inverter is mounted, the state estimation method comprising:

• an estimation step of estimating the state of the device, based on a magnitude of a specific frequency component of a physical quantity obtained from the device;
• and
• a restriction step of restricting the estimation step or an operation of the motor when a noise frequency component included in the physical quantity and the specific frequency component satisfy a predetermined relationship, wherein
• the restriction step is a first restriction step of restricting the estimation step so that a predetermined estimation result is output, or a second restriction step of restricting the operation of the motor so that no erroneous estimation is performed in the estimation step, and
• when a carrier frequency of the inverter is represented by fc, a sampling frequency that is a reciprocal of a cycle for sampling the physical quantity is represented by fs, and an electrical angular frequency of the motor is represented by f0, a frequency of the noise frequency component is
• a frequency given by any one of Expression 1, Expression 2, and Expression 3 below when the physical quantity is a DC signal, and
• a frequency given by any one of Expression 4, Expression 5, and Expression 6 below when the physical quantity is an AC signal, under a condition in which a greatest common divisor, which is at least 2, of two or more frequencies including the electrical angular frequency among the electrical angular frequency, the carrier frequency, and a frequency for sampling a modulation wave used for controlling the inverter does not exist:
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• where M and N are natural numbers.

A state estimation method for estimating a state of a device in which a motor is mounted, the state estimation method comprising:

• an estimation step of estimating the state of the device, based on a magnitude of a specific frequency component of a physical quantity obtained from the device;
• and
• a restriction step of restricting the estimation step or an operation of the motor, based on a magnitude of a periodic component included in a variable calculated based on the magnitude of the specific frequency component, wherein
• the restriction step is a first restriction step of restricting the estimation step so that a predetermined estimation result is output, or a second restriction step of restricting the operation of the motor so that no erroneous estimation is performed in the estimation step.