Abstract: A method of controlling a brushless permanent magnet motor includes determining a motor operating target. The method includes comparing the motor operating target to a set of pre-determined excitation timing parameter relationships. The method includes operating the motor in accordance with an excitation timing parameter relationship determined from the set of pre-determined excitation timing parameter relationships to provide a motor operating response close to the motor operating target. The method includes measuring a measured motor operating response, comparing the measured motor operating response to the motor operating target, and applying a correction factor to an excitation timing parameter of the motor when the measured motor operating response does not match the motor operating target, such that the measured motor operating response moves toward the motor operating target.

Abstract: A method is described for controlling an electric motor having a rotor. The method is carried out after a shutdown of the motor has been initiated. The method includes starting a timer in a motor controller, performing regenerative braking to recapture kinetic energy from the rotor as electrical energy, and using the recaptured electrical energy from the regenerative braking to power the motor controller. If the timer in the motor controller exceeds a predetermined timer value, a flag is set in memory in the motor controller to indicate that the motor has stopped.

Abstract: A method is described for controlling an electric motor having a rotor. The method is carried out after a shutdown of the motor has been initiated. The method includes starting a timer in a motor controller, performing regenerative braking to recapture kinetic energy from the rotor as electrical energy, and using the recaptured electrical energy from the regenerative braking to power the motor controller. If the timer in the motor controller exceeds a predetermined timer value, a flag is set in memory in the motor controller to indicate that the motor has stopped.

Abstract: A method is described for controlling an electric motor having a rotor. The method is carried out after a shutdown of the motor has been initiated. The method includes starting a timer in a motor controller, performing regenerative braking to recapture kinetic energy from the rotor as electrical energy, and using the recaptured electrical energy from the regenerative braking to power the motor controller. If the timer in the motor controller exceeds a predetermined timer value, a flag is set in memory in the motor controller to indicate that the motor has stopped.

Abstract: A method of controlling a brushless permanent magnet motor includes determining a motor operating target. The method includes comparing the motor operating target to a set of pre-determined excitation timing parameter relationships. The method includes operating the motor in accordance with an excitation timing parameter relationship determined from the set of pre-determined excitation timing parameter relationships to provide a motor operating response close to the motor operating target. The method includes measuring a measured motor operating response, comparing the measured motor operating response to the motor operating target, and applying a correction factor to an excitation timing parameter of the motor when the measured motor operating response does not match the motor operating target, such that the measured motor operating response moves toward the motor operating target.

Abstract: A method of controlling a brushless permanent-magnet motor that includes sequentially exciting and freewheeling a phase winding of the motor is provided. The phase winding is freewheeled when the phase current exceeds an upper threshold. The method further includes measuring a parameter that corresponds to either: (i) the magnitude of the phase current during or at the end of freewheeling when the phase winding is freewheeled for the fixed period of time, or (ii) the time interval during freewheeling or during excitation when the phase winding is freewheeled until the phase current falls below the lower threshold. The measured parameter is then compared against a saturation threshold, and the rotor is determined to be at a predetermined position. In response to determining that the rotor is at the predetermined position, the phase winding is commutated after a commutation period has elapsed.

Abstract: A method of determining the position of a rotor of a brushless permanent-magnet motor is provided. The phase winding is freewheeled when a phase current exceeds an upper threshold. The method further includes measuring a parameter that corresponds to either: (i) the magnitude of the phase current during or at the end of freewheeling when the phase winding is freewheeled for the fixed period of time, or (ii) the time interval between the start and end of freewheeling or the start and end of excitation when the phase winding is freewheeled until the phase current falls below the lower threshold. The measured parameter is then used to define a saturation threshold. The phase winding is subsequently excited and freewheeled in the same manner, and the parameter is measured again. The method then compares the measured parameter against the saturation threshold, and determines that the rotor is at a predetermined position.

Abstract: A surface cleaning appliance having a cleaner head that includes an agitator and a motor for driving the agitator. The appliance includes a switch coupling the motor to a supply voltage, a voltage sensor for measuring the magnitude of the supply voltage, a current sensor for measuring the magnitude of current through the motor, and a controller configured to output a PWM signal for controlling the switch. The controller then adjusts the duty cycle of the PWM signal in response to changes in the supply voltage and in response to changes in the current through the motor.

Abstract: A method of determining the position of a rotor of a brushless permanent-magnet motor is provided. The phase winding is freewheeled when a phase current exceeds an upper threshold. The method further includes measuring a parameter that corresponds to either: (i) the magnitude of the phase current during or at the end of freewheeling when the phase winding is freewheeled for the fixed period of time, or (ii) the time interval between the start and end of freewheeling or the start and end of excitation when the phase winding is freewheeled until the phase current falls below the lower threshold. The measured parameter is then used to define a saturation threshold. The phase winding is subsequently excited and freewheeled in the same manner, and the parameter is measured again. The method then compares the measured parameter against the saturation threshold, and determines that the rotor is at a predetermined position.

Abstract: A method of controlling a brushless permanent-magnet motor that includes sequentially exciting and freewheeling a phase winding of the motor is provided. The phase winding is freewheeled when the phase current exceeds an upper threshold. The method further includes measuring a parameter that corresponds to either: (i) the magnitude of the phase current during or at the end of freewheeling when the phase winding is freewheeled for the fixed period of time, or (ii) the time interval during freewheeling or during excitation when the phase winding is freewheeled until the phase current falls below the lower threshold. The measured parameter is then compared against a saturation threshold, and the rotor is determined to be at a predetermined position. In response to determining that the rotor is at the predetermined position, the phase winding is commutated after a commutation period has elapsed.

Abstract: A method is described for controlling an electric motor having a rotor. The method is carried out after a shutdown of the motor has been initiated. The method includes starting a timer in a motor controller, performing regenerative braking to recapture kinetic energy from the rotor as electrical energy, and using the recaptured electrical energy from the regenerative braking to power the motor controller. If the timer in the motor controller exceeds a predetermined timer value, a flag is set in memory in the motor controller to indicate that the motor has stopped.

Abstract: A method of determining the parked position of a rotor of a permanent-magnet motor, including applying a first voltage to a phase winding of the motor, measuring a first parameter, removing the first voltage, waiting for current in the phase winding to decrease to zero, applying a second voltage having the opposite polarity, measuring a second parameter, comparing the first parameter and the second parameter, and determining that the rotor is in a first parked position if the first parameter is less than the second parameter, and that the rotor is in a second parked position if the first parameter is greater than the second parameter. The first parameter and the second parameter each correspond to one of (i) the time taken for current in the phase winding to exceed a threshold, and (ii) the magnitude of current in the phase winding at the end of a time interval.

Abstract: A method of controlling a brushless permanent-magnet motor. The method includes dividing each half of an electrical cycle of the motor into a conduction period followed by a primary freewheel period. The conduction period is then divided into a first excitation period, a secondary freewheel period, and a second excitation period. The method then involves exciting a winding of the motor during each excitation period and freewheeling the winding during each freewheel period. The secondary freewheel period has a position and length within the conduction period that acts to reduce the harmonic content of current in the winding relative to back EMF in the winding. As a result, the efficiency of the motor is improved.

Abstract: A method of controlling a brushless motor. The method includes measuring a temperature of the motor, adjusting a control value in the event that the measured temperature is lower than a threshold, and exciting a winding of the motor. The control value is then used to define an attribute of excitation, and the adjustment to the control value reduces the input power of the motor.

Abstract: A method of controlling a brushless permanent-magnet motor. The method includes commutating a winding of the motor at times relative to zero-crossings of back EMF in the winding. Commutation is then advanced when the motor operates over a first speed range, and commutation is retarded when the motor operates over a second speed range higher than that of the first speed range.

Abstract: A controller for a brushless motor that includes a PWM module configured in half-bridge or full-bridge mode. The PWM module outputs control signals for controlling the excitation of a winding of the motor, and one of the duty cycle and the period of the PWM module defines a time at which the winding is commutated.

Abstract: A controller for a brushless motor that is configured to operate in normal mode or under-voltage mode. When operating in normal mode, the controller generates control signals for exciting a winding of the motor, monitors the magnitude of an input voltage, and switches to under-voltage mode in the event that the input voltage drops below an under-voltage threshold. When operating in under-voltage mode, the controller suspends excitation of the winding, monitors the magnitude of the input voltage, monitors the magnitude of a supply voltage used to power the controller, switches to normal mode in the event that the input voltage exceeds a restart threshold, and resets itself in the event that the supply voltage drops below a brown-out threshold.

Abstract: A controller for a brushless motor that is configured to operate in normal mode or under-voltage mode. When operating in normal mode, the controller generates control signals for exciting a winding of the motor, monitors the magnitude of an input voltage, and switches to under-voltage mode in the event that the input voltage drops below an under-voltage threshold. When operating in under-voltage mode, the controller suspends excitation of the winding, monitors the magnitude of the input voltage, monitors the magnitude of a supply voltage used to power the controller, switches to normal mode in the event that the input voltage exceeds a restart threshold, and resets itself in the event that the supply voltage drops below a brown-out threshold.

Abstract: A method of controlling a brushless permanent-magnet motor. The method includes dividing each half of an electrical cycle of the motor into a conduction period followed by a primary freewheel period. The conduction period is then divided into a first excitation period, a secondary freewheel period, and a second excitation period. The method then involves exciting a winding of the motor during each excitation period and freewheeling the winding during each freewheel period. The secondary freewheel period has a position and length within the conduction period that acts to reduce the harmonic content of current in the winding relative to back EMF in the winding. As a result, the efficiency of the motor is improved.

Abstract: A surface cleaning appliance having a cleaner head that includes an agitator and a motor for driving the agitator. The appliance includes a switch coupling the motor to a supply voltage, a voltage sensor for measuring the magnitude of the supply voltage, a current sensor for measuring the magnitude of current through the motor, and a controller configured to output a PWM signal for controlling the switch. The controller then adjusts the duty cycle of the PWM signal in response to changes in the supply voltage and in response to changes in the current through the motor.