The invention provides a monitor circuit, which is used for a fan and receives a driving current and a driving voltage of the fan. The monitor circuit includes sensing circuits and a microcontroller. The sensing circuits respectively sense statuses of the fan and output sensing values. The microcontroller is used for monitoring whether the sensing values exceed preset value ranges respectively to obtain comparison results. The microcontroller outputs warning signals according to the comparison results. Each of the warning signals has a specific frequency.

The present invention achieves highly accurate control characteristics by estimating an induced voltage coefficient of a magnet motor without rotary auto-tuning.

A first power P.sub.c is calculated on the basis of the output voltage and output current of the magnet motor, and a second power P.sub.c{circumflex over ( )} is calculated on the basis of the electric circuit constant, current command, output frequency, and induced voltage coefficient of the magnet motor. The induced voltage coefficient is estimated so that the calculated first power follows the second power, and the driving of the magnet motor is controlled in accordance with the induced voltage coefficient.

A method for estimating a magnet temperature of a rotor magnet within a rotary electric machine includes, while a rotor of the electric machine is stationary, injecting a high-frequency voltage component onto a control voltage of the electric machine, via a controller, to generate an adjusted voltage command, and extracting a high-frequency component of a resulting current as an extracted high-frequency component. The method also includes calculating an inductance value of the electric machine using the extracted high-frequency component of the resulting current. The magnet temperature is estimated using the calculated inductance value and an angular position of the rotor. The method includes controlling an operation of the electric machine using the estimated magnet temperature. An electric powertrain uses the electric machine and controller noted above.

A motor driving system includes motor driving circuitry configured to operate an electric motor. The system further includes a controller that is configured to send a signal to energize the electric motor and to measure a back electromotive force voltage of the electric motor. The controller is further configured to determine a temperature value based on the measured back electromotive force voltage using a back electromotive force voltage mapping that maps back electromotive force voltages to temperature values. The controller is further configured to determine an expected winding resistance value based on the determined temperature value using a resistance mapping that maps winding resistance values to temperature values. The controller is further configured to measure a winding resistance of the electric motor, to compare the measured winding resistance of the electric motor to the expected winding resistance value, and to output a match result indication based on the comparison.

A magnet temperature estimating device for a motor including a rotor having magnets and configured to output a rotational motive force, and a stator having a plurality of coils opposing the rotor with a gap therebetween, is provided. The device includes a sensor configured to detect an induced voltage induced by rotation of the rotor, and a controller configured to control the motor by supplying power to the plurality of coils in response to an input of a detection signal from the sensor. Gaps adjacent to each magnet in a rotation direction of the rotor are formed in the rotor. The controller estimates a temperature of the magnet based on the induced voltage detected when the magnet opposes any one of the plurality of coils, according to the rotation of the rotor.

A magnet temperature estimating device for a motor provided with a rotor having magnets and configured to output a rotational motive force, and a stator having a plurality of coils opposing the rotor with an aperture therebetween, is provided. The device includes a sensor configured to detect an induced voltage induced by rotation of the rotor, and a controller configured to control the motor by supplying power to the plurality of coils in response to an input of a detection signal from the sensor. The controller estimates a temperature of one of the magnets based on an amplitude of a frequency spectrum corresponding to a given frequency, among frequency components constituting the induced voltage.

Method for operating a power converter for a permanently excited electric machine, wherein temperature information, which describes a temperature of at least one permanent magnet of the electric machine, is determined by means of an observer as a function of operating parameters of the electric machine, and the power converter is controlled as a function of the temperature information, wherein a computing device, which handles processes in time slices, carries out a first process in a first time slice for detecting parameter values for determining the operating parameters and carries out a second process, which determines the temperature information, in a second time slice, which is retrieved less frequently than the first time slice.

A DC motor including a continuous rotation rotor; a first inductor characterized by first parameters; a second inductor characterized by second parameters; a voltage supply unit; a measurement unit for detecting time instants when a first induced voltage in the first inductor equals a second induced voltage in the second inductor; and a control unit for controlling the application of drive voltage pulses to the inductors. The rotor faces first the second inductor before facing the first inductor when being rotated. At least one of the second parameters is selected different from a corresponding parameter of the first parameters such that a maximum induced voltage in the first inductor is greater than a maximum induced voltage in the second inductor. The control unit is arranged to trigger each of the drive voltage pulses after a detection of an equal induced voltage in the first and second inductors.

A method for estimating a magnet temperature of a rotor magnet within a rotary electric machine includes, while a rotor of the electric machine is stationary, injecting a high-frequency voltage component onto a control voltage of the electric machine, via a controller, to generate an adjusted voltage command, and extracting a high-frequency component of a resulting current as an extracted high-frequency component. The method also includes calculating an inductance value of the electric machine using the extracted high-frequency component of the resulting current. The magnet temperature is estimated using the calculated inductance value and an angular position of the rotor. The method includes controlling an operation of the electric machine using the estimated magnet temperature. An electric powertrain uses the electric machine and controller noted above.

A controller detects a rotor magnet temperature based on an actively detected back electromotive force (BEMF) voltage of the motor. The controller detects the BEMF voltage by commanding the injection of a direct-axis (d-axis) current into the motor while the motor is spinning but otherwise commanding no torque. The controller actively detects the BEMF voltage in that the controller purposely injects a known quantity of d-axis current at a chosen time during which the controller detects or is aware that the motor is commanding no torque. Using a quadrature-axis (q-axis) voltage equation, which describes the relationship between a voltage command, the current, the BEMF voltage, and reactance in the q-axis, the controller solves for the BEMF voltage with the voltage command, the current, and the q-axis reactance being known to the controller. The controller detects the rotor magnet temperature based on the BEMF voltage.