Abstract: The invention relates to a method in connection with an inverter, the inverter comprising a direct voltage intermediate circuit, an optimum switching table and output power switches. The method comprises steps where phase currents (iA, iC) of the inverter are converted to a synchronous dq coordinate system in order to achieve vector components (id, iq), the synchronous current vector components (id, iq) are low pass filtered in order to achieve current vector components (id,jpf, iq,jpf), a current reference (iq,ref) is generated in the direction of the q axis, a current reference (id,ref) is generated, a torque reference (te,ref) is generated, an absolute value reference (|?|ref) of a flux linkage is generated from the currents and switching commands are formed on the basis of the torque reference (te,ref) and the flux reference (|?|ref) using the optimum switching table (5).

Abstract: One embodiment of the present invention is a method to control input to an alternating current (AC) induction motor from a power supply that includes steps of: (a) determining a measure of reactive power (VAR) in two input lines to the motor during a time period; and (b) maintaining an SSR (solid state relay) connected in series between the power supply and the motor in a non-conducting state for a subsequent time period, the length of which subsequent time period is determined by analyzing the measure of VAR.

Abstract: Improved voltage stiffness in the output voltage of an inverter used for a motor drive is obtained by a minor voltage feedback loop connecting the output of the inverter to a three-phase input in a vector domain.

Abstract: In a synchronous motor control device that corrects a deviation in rotational position which is related to a rotational position detector for a synchronous motor on which vector-control is performed, the synchronous motor control device includes: a current instruction generator that disables a torque instruction to set d-axis and q-axis current instructions as zero when a phase correction instruction is inputted; a current controller that outputs d-axis and q-axis voltage instructions based on the d-axis and q-axis current instructions; a phase correction quantity detector for determining the amount of offset in which the d-axis voltage instruction becomes zero when the phase correction instruction is inputted and the d-axis voltage instruction is not zero; an adder for adding a rotor positional angle and the amount of offset; and a voltage converter for determining three-phase voltage instructions based on the additional value, the d-axis and q-axis voltage instructions.

Abstract: In regenerative braking mode, an inverter converts, according to PWMC signal from a control unit, an AC voltage generated by a motor into a DC voltage to supply the converted DC voltage to an up-converter which down-converts the DC voltage to charge a DC power supply. The control unit receives voltage V2 from a voltage sensor to stop the up-converter if voltage V2 is higher than a predetermined value. The control unit further receives voltage Vf from a voltage sensor that is applied to a DC/DC converter and stops the up-converter if voltage Vf is higher than a predetermined value. Moreover, the control unit receives voltage V1 of the DC power supply from a voltage sensor to stop the up-converter if voltage V1 does not match voltage V2.

Abstract: The present invention discloses devices and methods for improved starting and stopping of rotary motors. A rotary electrical machine (3) is supplied with a voltage from a voltage supply (10). The magnitude of a phase current is measured. The measured current value (IM) and applied voltage (U) is compared with what is expected for a predetermined target slip (ST), by means of a relation between phase current, applied voltage and slip. The comparison gives a discrepancy value, which is used to create a regulation signal (?U) to the voltage supply (10). To start and stop the machine, the target slip is increased and decreased, respectively, in a predetermined manner. The means for regulation may be provided as a separate add-on unit to existing soft starter equipment.

Abstract: A magnetic flux estimator 7 of a controller used for sensorless vector-controlling of an induction motor computes an estimated speed ?rest and an estimated phase ?lest from input ?-phase and ?-phase voltage instructions V?*, V?* and ?-phase and ?-phase currents is?, is?. A speed corrector 8 receives these information items and determines a difference between a differential value output from a phase estimator and an additionally input slip angular speed; that is, a deviation ??res. Further, a primary delay integral value is determined by subtracting a slip angular frequency ?s from the deviation, and the primary delay integral value is multiplied by a correction gain, to thereby produce a correction to be made on the estimated speed ?rest. Thus, a more accurate estimated speed ??rest is obtained.

Abstract: A method and system for the sensorless estimation of the states of the mechanical subsystem of a motor are disclosed. In particular, the method and system split the estimation problem into two sub-problems: the estimation of motor parameters as a function of position, and the determination of the states of the mechanical subsystem of the motor using the estimated parameters via a state observer. Motor current and PWM voltage in a polyphase system is measured or otherwise determined and converted into current and voltage in ?-? coordinates. A least square estimator is constructed that uses the voltage and current in ?-? coordinates and provides an estimate of the motor parameters, and in particular, the inductances of the motor, which are a function of the rotor position.

Abstract: Host control section 8 is provided with simulation model 8c for simulating the signal transmission characteristics of an electric motor control device. Host control section 8 performs an operation on the actual position command signal ?ref that is supplied from the host device in accordance with the simulation model, calculates the speed and position of the electric motor corresponding to the actual position command signal ?ref, and applies this speed and position as first simulation speed signal ?F and first simulation position signal ?F, respectively, with each second control sampling period t2. Host control section 8 further generates a linear combination of ?ref??F and ?F using, as combination coefficients, constants determined by parameters that characterize the simulation model, and supplies this linear combination as feedforward torque signal TFF for each second control sampling period t2.

Abstract: A motor driver circuit including an inverter, a motor-drive-current detector, a current detector, and a controller operable to calculate a d-axis current difference between the detected d-axis current and a commanded d-axis current value, and a q-axis current difference between the detected q-axis current and a commanded q-axis current value. The controller is further operable on the basis of the calculated d-axis and q-axis current differences, to calculate a d-axis difference signal which is not influenced by a q-axis input voltage of the motor and which is influenced by a d-axis input voltage of the motor, and a q-axis difference signal which is not influenced by the d-axis input voltage and which is influenced by the q-axis input voltage. The controller controls the inverter, so as to zero the d-axis and q-axis difference signals.

Abstract: A motor driving apparatus includes a single-phase rectifier circuit having an input connected to a single-phase AC power supply, an inverter circuit that is connected to the single-phase rectifier circuit and applies a current and a voltage to the motor 2, and an inverter control unit for controlling the inverter circuit. The inverter control unit controls the current applied to the motor, i.e., the output of the inverter circuit, so that the inverter input voltage becomes equal to the absolute value of the voltage of the single-phase AC power supply 1.

Abstract: A full-closed control apparatus for performing velocity control based on a velocity signal of a motor and performing position control based on a position signal of a load driven by the motor, including: an equivalent rigid system velocity loop model; a band-pass filter; an amplitude adjuster; and a unit for inputting a velocity instruction of a velocity control loop into the equivalent rigid system velocity loop model, inputting a difference signal obtained by subtracting an output of the equivalent rigid system velocity loop model from a velocity signal of the load into the band-pass filter, inputting an output of the band-pass filter into the amplitude adjuster and outputting a signal obtained by adding an output of the amplitude adjuster to an output of a position controller, as a new velocity instruction.

Abstract: A technique for controlling an AC motor. An electric power is output to the AC motor. The output current of an electric power converter is controlled based on a difference signal of an output current detection signal and a current command signal of the electric power converter. When the AC motor is in a free run condition, current control is conducted by forcing the current command signal to be zero so that a current in the AC motor is made zero. The amplitude and phase and angular velocity of a residual voltage of the AC motor are found based on a calculated output voltage command.

Abstract: A circuit for controlling the power supply voltage of an electric motor includes means for detecting the difference between a mains voltage and a reference voltage, and means for generating alternating correction voltage whose frequency is equal to the frequency of the mains voltage and which is phase-shifted with respect to the mains. The phase shift between the mains voltage and the correction voltage is proportional to the between the mains voltage and the reference voltage, and the correction voltage is added to the mains voltage.

Abstract: The specification describes a method and a detection module for determining the rotor position of an electromotor having a plurality of motor phase windings, in which, for determining the rotor position, the polarity of at least one motor phase voltages, which is induced in at least one first motor phase winding, is determined as at least one first polarity value, through comparison to a reference value. The reference value is, for example, a real or simulated star-point voltage. In one embodiment of the invention, the determination of the at least one first polarity value is synchronized to switch-on time point for supplying current to the at least one first or second motor phase winding, and in one specific embodiment, at least one first polarity value is determined after a preestablished delay, which follows the switch-on time point.

Abstract: An electrical power system includes an electric power source providing AC power to a load. A wideband voltage controller provides a wideband control signal vector to the electric power source. A fundamental component removal module interfaces to the AC power, receiving a fundamental component Park vector of the AC voltage, and providing a resonant frequency content in Park vector format of the AC current. A narrow band voltage regulator uses a resonant component Park vector of the AC current and the resonant frequency content in Park vector format to provide a narrow band output vector signal. A dead band compensating circuit rotates narrow band output vector signal by a transport lag compensation angle to provide a compensated control signal vector to the electric power source. The wideband control signal vector and compensated control signal vector are used to regulate the AC power so that the resonant frequency content is attenuated.

Abstract: Method/apparatus for controlling input to an AC induction motor from a power supply that determines a measure of reactive power in two input lines to the motor from the power supply, and uses that measure of reactive power to control an SSR in series between the power supply and the motor. In one arrangement, a voltage difference between the two input lines and a current in one of the lines is used to determine the measure of reactive power.

Abstract: A controller for a motor and a method for controlling the operation of the motor. The controller includes a model of the motor, where the model is utilized to determine modeled values of first and second motor variables. An estimated value of slip is adjusted based at least in part on a comparison of the modeled value of the second motor variable and an estimated value of the second motor variable which is based at least in part on a value of bus voltage and a value of bus current. As the estimated value of slip is adjusted, the modeled values are updated and the voltage utilized to energize the motor is thereby updated to provide control of the motor based on the control of the first motor variable.

Abstract: A rotor angle detecting apparatus for a DC brushless motor is capable of detecting the angle of the rotor of the DC brushless motor with accuracy without the need for a position detecting sensor. A motor controller has a high-frequency voltage imposer, an angle detector, a U-phase current sensor, and a W-phase current sensor for detecting the rotor angle of the DC brushless motor. The angle detector detects the rotor angle &thgr; using a current value IU_s detected by the U-phase current sensor, a current value IW_s detected by the W-phase current sensor, and high-frequency components depending on high-frequency voltages vu, vv, vw, when the high-frequency voltages vu, vv, vw are imposed on command values VU_c, VV_c, VW_c for three-phase voltages by the high-frequency voltage imposer.

Abstract: A method and apparatus for use with an induction machine system including a controller and d and q-axis current feedback loops, the controller receiving a frequency command signal and generating d and q-axis voltage command signals, the method for limiting load current to a level below a limit current at low operating frequencies, the method comprising the steps of identifying an operating frequency as a function of the d and q-axis feedback currents, where the operating frequency is below a low threshold value: comparing a feedback current to the limit current; and where the feedback current exceeds the limit current, reducing the q-axis voltage command value.

Abstract: This invention relates to a system for limitation of the output current from a speed controller for three-phase asynchronous electric motors, comprising a PWM type converter in which the electronic switches are controlled by a microcontroller circuit (Mc), characterized by the fact that the microcontroller circuit comprises means (LIC) of calculating the modulus of the current vector using motor phase current measurements, and comparing it with a limitation set value in order to obtain a limitation error (y) and to calculate a correction voltage (&Dgr;V) that is added to the control voltage (V) applied to the motor.

Abstract: A motor driver having output circuits each including upper and lower side switching elements connected in series. The motor driver includes: a current detection resistance connected in series with the output circuits in common; a phase switch circuit for turning ON a switching element on one side of one of the output circuits for a time period corresponding to a predetermined electrical angle and switching switching elements on the other side of a plurality of output circuits among the remaining ones of the output circuits; and an ON-period control section for generating a signal for controlling the switching operation so that each of periods obtained by dividing the time period includes a first period in which a plurality of switching elements are turned ON and a second period in which one of the switching elements turned ON in the first period is kept ON.

Abstract: If a speed instruction value is less than a predetermined value, the output current of a power-conversion unit is controlled to be larger than a current value in an ordinary no-load operation, or a frequency instruction value is calculated based on a speed instruction value in place of an estimated speed.

Abstract: The invention relates to a method for control of the speed of rotation of a separately excited direct current motor for model vehicles, the speed of rotation of the motor being controlled by means of a pulse sequence, the motor being alternately supplied with a supply voltage during a switch-on period and disconnected from the supply voltage during a switch-off period, the duration of the switch-off period being dependent on the deviation of an actual value from a set value for the speed of rotation of the motor. In order to further develop the method in such a way that the separately excited motor has a low noise output and stable control is possible over a wide range of speed of rotation, it is proposed that a pulse width modulated signal is provided, the pulse width of which is dependent on the average torque loading of the motor, and that the pulse width modulated signal is combined with the pulse sequence by an AND-operation.

Abstract: An induction motor control system senses the zero-cross angle of a current waveform applied to the motor's phase windings and computes the difference between the sensed current zero-cross angle and a predetermined demand voltage angle to estimate a power factor angle. The estimated power factor angle is compared to a predetermined desired power factor angle, and the voltage applied to the phase windings is adjusted in response to the difference between the estimated power factor angle and the desired power factor angle.

Abstract: The electric car controller is characterized in that evaluation two-phase/three-phase converting means (15) for calculating a three-phase evaluation current indication value is provided in control means, and current detected value from current detecting means (8) and evaluation current indication value are compared with each other by a deviation computing means (17). This result is evaluated by error evaluation means (18), and is sent to target command computing means (10), whereby the operation of a drive apparatus is stopped or continued.

Abstract: An induction motor control apparatus includes a first constant correction unit for correcting primary resistance based on quantity obtained by multiplying quantity of a voltage command from a frequency voltage control unit by the output of a correction unit, the quantity of the voltage command being a result of partial differentiation with the primary resistance; a second constant correction unit for correcting the inductance based on quantity obtained by multiplying quantity of the voltage command, the quantity of the voltage command being a result of partial differentiation with the inductance; and a third constant correction unit for correcting the inductance ratio based on quantity obtained by multiplying quantity of the voltage command, the quantity of the voltage command being a result of partial differentiation with the inductance ratio, suppressing the deterioration of control performance caused by the setting errors.

Abstract: A motor drive 50 of an induction motor IM includes an inverter section 20, a charger 60, a charging and discharging circuit 70 and a control section 80. The charger 60 is for storing regenerated electric power of the induction motor via the inverter section. The charging and discharging circuit 70 is for making the charger charge electric power and making the charger discharge the electric power. The control section carries out control of the charging and discharging circuit for making the charger charge the electric power when the induction motor generates regenerated electric power and making the charger supply the electric power to the induction motor in accelerating the induction motor or in electricity interruption.

Abstract: A method of establishing motor speed control, the method comprising the acts of generating a desired speed command, indirectly measuring the slip of the motor, and adjusting the speed command in response to the slip to maintain a constant speed.

Abstract: A method of estimating the speed of an induction motor and the magnetic flux of a rotor is disclosed. The method consists of the steps of a) obtaining some measurable or calculable variables for estimating the speed of the induction motor and the magnetic flux of the rotor; b) calculating a parameter as a counter-electromotive force of the motor derived from the variables obtained in the step a); c) estimating the speed of the motor by use of the parameter calculated in the step b), an estimated value of the parameter, and the obtained variables; and d) estimating the magnetic flux of the rotor by use of an estimated value of the speed estimated in the step c) and the parameter.

Abstract: Method and system for controlling an induction machine are provided. The method allows to sense rotor position of the induction machine using a relatively low-resolution rotor position sensor configured to supply a stream of pulses indicative of angular increments as the rotor position changes. A memory device is used for storing a synchronous angle boost function. The method further allows to retrieve from the memory device at least one function parameter for providing a synchronous angle boost during a start up mode of operation of the induction machine. Upon sensing a predetermined number of pulses from the rotor position sensor, the method allows to switch from the start up mode of operation to a normal mode of operation, wherein the boost provided to the synchronous angle is discontinued upon switching to the normal mode of operation.

Abstract: Apparatus and methods that control motor power in an electric motor such as a stepper motor, advantageously allow improved open-loop motor performance, allow reduced motor hunting, detect stalls, detect out-of-synchronization errors, control and synchronize multiple motors, and can automatically configure motor parameters to provide a motor with a power and load combination that gives an optimized performance. In one embodiment, an EMF commutation circuit detects a rotor position at which to sequence the motor to provide an optimized performance from the motor. In another embodiment, pulse width modulation (PWM) controls power, and the embodiment measures the rotor position within a detent position. Particular embodiments of the invention utilize a motor controller adapted to respond to a commutation signal, a pulse, or both in conjunction with a sensing device, such as an EMF detector or an optical encoder.

Abstract: A monitoring apparatus for monitoring operation of a no-back device of an actuator assembly driven by a motor, the apparatus comprising sensor device operable to sense an operating parameter of the motor for determining when the motor's output drive is in a direction opposite to a selected direction of motor output drive.

Abstract: In order to supply an AC motor control apparatus which identifies the type of motor automatically, the AC motor control apparatus has a motor type identification means by which the type of motor connected to the motor control apparatus is identified by issuing the appropriate voltage command for motor type identification and judging from the detected current whether the motor rotor is equipped with a magnet and has magnetic salience. The AC motor control apparatus has a control scheme selection means which selects the appropriate control scheme according to the above-identified type of motor and controls the driving of the motor.

Abstract: A fuel cell power plant (1) and a rechargeable battery (2) are connected in parallel to an electric motor (3) of a fuel cell powered vehicle, and the output voltage of the fuel cell power plant (1) is regulated by a converter (4). A temperature sensor (5) detects the temperature of the electric motor (3), and a controller (6) controlling the output voltage of the converter (4) to a predetermined high voltage value when the temperature of the electric motor (3) is greater than a predetermined temperature, thereby preventing the excessive rise of the temperature of the electric motor (3).

Abstract: A method and apparatus for controlling flux in an induction motor. During initial start of an induction motor drive the motor flux has to be charged up. The method provides time optimal flux forcing under limited inverter ampere capability. Command stator flux and current are generated and coordinated through a motor flux model. Charging of the motor flux and flux current are accelerated up to nominal operating values in coordinated manner.

Abstract: A method for sensorless estimation of the relative position between the stator and the rotor of a three-phase synchronous motor during operation. The method comprises the steps of low-pass filtering of the terminal voltage, low-pass filtering of the terminal current, high-pass filtering of the terminal current and determining the rotor speed. Next the relative angular position is determined from the filtered magnitudes and corrected with an angular correction derived from the rotor speed.

Abstract: In a small electric motor vehicle equipped with an electric motor for driving wheels through a reduction gear mechanism, a first predetermined voltage is immediately applied to the electric motor when a drive-off instruction is generated from vehicle standstill and then the voltage is increased at a predetermined rate until the voltage exceeds a second predetermined voltage, and is then controlled such that the driving speed converges to a desired speed. With this, since the application of the first predetermined voltage slightly rotates the electric motor to take up reduction gear mechanism backlash, shock at drive-off caused by reduction gear mechanism backlash can be reduced or eliminated even when a high-capacity electric motor is used to enhance hill-climbing performance, and smooth drive-off is possible.

Abstract: An apparatus for controlling multiple vehicle systems includes a single power supply that provides a direct current source. The power supply is comprised of a thirty-six volt (36 V) battery power distribution system. A converter is electrically connected to the power supply to convert direct current to alternating current. A plurality of induction motors are used to operate various vehicle systems. The motors receive alternating current via electrical connections between the converter and the motors. A central processor is connected to relays sending power to each of the motors and provides control signals to the motors based on input from control members used to activate each of the various vehicle systems. At least one sensor is associated with each of the motors to monitor voltage or current of the respective motor and to generate a diagnostic signal that is sent to the processor.

Abstract: A sensorless vector control apparatus includes a speed controller for receiving a speed command value from a user and outputting a synchronous speed; a ‘d’ and ‘q’ axis voltage command unit for receiving the synchronous speed and outputting a ‘d’ axis voltage and a ‘q’ axis voltage; a voltage converter for receiving the ‘q’ axis voltage and the ‘d’ axis voltage, and converting the two phase voltages into three phase voltages; and an inverter for receiving the three phase voltages and controlling a speed of an induction motor. Since the vector control may be performed over the whole velocity range without using a speed sensor, the sensorless vector control apparatus may be used with advantage.

Abstract: A variable speed power tool may include a speed adjusting device and/or a maximum speed adjusting device for adjusting the operating speed, and a fixed operating speed switch. An operator adjustable speed adjusting device having a position maintaining mechanism also may be utilized. When manipulated by the operator, the fixed operating speed switch gives priority to the adjusted position of the speed adjusting device and adjusts the operating speed to a preset operating speed. In the alternative, a switching device and an internal integrated circuit may be utilized to adjust the operating speed to a target speed using feedback control. The switching device preferably selects a voltage corresponding to the target speed from either a voltage representative of the position of the speed adjusting device or a predetermined voltage representative of the present operating speed.

Abstract: A system (10) for controlling the torque of an induction motor (12) utilizes a flux observer (14). The flux observer (14) receives stator current inputs (16, 18) and a rotor speed estimate (80) and then outputs a rotor flux estimate (20) that provides increased motor control stability at all speeds.

Abstract: A method and apparatus for achieving constant air flow rate economically utilizes an induction blower motor with control settings determining the motor excitation voltage. A memory stores, for a variety of motor speeds, a graph of the speeds plotted against a proportionality constant of flow rate to fan speed for the selected motor system on one axis and motor control settings on the other axis. The only monitoring necessary to achieve the constant flow rate is thus the sensing of fan rotational speed. The measured fan speed is compared against the proportionality constant needed for the selected constant air flow rate and a motor excitation voltage is derived to achieve that proportionality constant. When the system load changes significantly, thereby causing significant fan speed change, a cascaded control loop is used whereby the speed changed induced by each control voltage adjustment is monitored until the desired constant flow rate is again attained at the new load level.

Abstract: A method and apparatus for controlling the torque of and reducing torque ripple in a permanent magnet motor without using current sensors. By eliminating the need for current sensors, low frequency torque ripple is reduced. A voltage mode control method is implemented to control the motor. In response to the position and speed of the rotor and a torque command signal, a controller develops motor voltage command signals indicative of the voltage required to produce the desired motor torque. A rotor position encoder determines the angular positions of the rotor. From the angular positions of the rotor, a speed measuring circuit determines the speed of the rotor. The position and speed signals are applied to the controller. The controller uses this information and develops the motor voltage command signals indicative of the voltage needed to produce the desired motor torque. An inverter is coupled between a power source and the controller.

Abstract: An efficiency-maximization motor controller that includes a use method has power conveyance to an induction motor (1) with a digital signal processor (DSP) (8) that calculates and optimizes supply of current for existent motor loading from a power supply (2) and mains voltage through a control element (5). The control element can include a standard triac, a field-effect transistor, an insulated gate bipolar transistor, a 3 quadrant triac or other select control element. Digital calculation and motor-control feedback of current requirements for motor loading and other motor parameters are calculated in millionths of seconds to provide motor-current optimization for all motor-use conditions. Calculation of motor-load requirement for current and supply of that current are effectively simultaneous.

Abstract: A method of reconnecting a motor to a motor drive comprises controlling a current which flows through the motor using a current regulator. The current regulator produces a voltage command output based on a current command input. A current is commanded at the current command input of the current regulator. Back EMF measurements are acquired at different instants in time by monitoring the voltage command output of the current regulator. Back EMF phase angles are determined for a plurality of the instants in time based on a respective plurality of the back EMF measurements. A frequency of the back EMF is determined based on the back EMF angles determined for the plurality of instants in time. The motor drive is reconnected to the motor based on the frequency of the back EMF.

Abstract: A synchronous motor control system includes a synchronous motor 1, an inverter 3 and a controller 4 wherein a current differential detecting unit 13 detects a variation of a motor current when the three phases of the motor 1 is short circuited by the inverter 3, namely at the moment when a carrier wave in a PWM signal generator 9 assumes maximum or minimum value, in a calculating unit 14 a phase &ggr; from &agr; axis of a stationary coordinate system to a three phase short circuited current differential vector is calculated, a phase &dgr; is estimated from d axis to the three phase short circuited current differential vector by making use of d axis current id and q axis current iq on d-q axes coordinate system in the controller 4, thereafter the magnetic pole position &thgr; with respect to &agr; axis is calculated from the phases &ggr; and &dgr;, based on thus calculated magnetic pole position &thgr;, d-q axes control units 11, 7 and 8 are constituted to control the synchronous motor, thereby a highly reliab

Abstract: A power electrical system is disclosed for a microturbine power generator. The invention permits the microturbine to be started using an external DC power source. The DC voltage is converted to a variable DC voltage by means of a bi-directional buck-boost circuit, DC bus and a DC-to-AC converter. The DC-to-AC converter produces at its output a fixed voltage pattern whose frequency is gradually increased in concert with the DC voltage, to accelerate the microturbine from standstill to startup speed. Once the microturbine is started, the excitation is discontinued, and the DC bus and DC-to-AC are used to produce output AC power at a voltage level and frequency to match an electrical load.

Abstract: An apparatus (10) for controlling an electric motor (36) having a plurality of motor phases includes a motor controller (32) that controls energization of each phase of the plurality of motor phases. A compensation circuit (56, 84, 104) is associated with each phase of the plurality of motor phases. The compensation circuit (56, 84) of one phase of the plurality of motor phases adjusts a control parameter of another phase of the plurality of motor phases an amount functionally related to an electrical characteristic of the one phase in response to determining a diminished operating characteristic of the one phase.

Abstract: A method for detecting a zero-cross event of an induced back electromotive force (BEMF) or of a nullification instant of a periodic current in a PWM driven winding, by circuits generating an analog signal representative of the induced BEMF or of the nullification instant of the periodic current, comparing the analog signal with zero and producing a first logic signal, generating a PWM driving signal, and storing a time between two consecutive zero-cross events, is provided. The method may include storing a time between a last two zero-cross events and synchronizing the PWM driving signal from a last zero-cross event having a duration equal to a difference between an established time based upon the stored time interval and a first time. If a new zero-cross event is not detected within the established time, switching of the PWM driving signal may be disabled for a time having a maximum duration equal to a second time or until a new zero-cross event is detected.