Abstract: An object of the present invention is to achieve stable inverter control by means of current detection using one current sensor in all of periods in which overmodulation control is performed. An inverter controller includes a ?-axis current calculation section that holds, in advance, a ?-axis current arithmetic expression including a direct current as a parameter, and calculates a ?-axis current using a direct current detected by a current sensor for the ?-axis current arithmetic expression.

Abstract: A power converter according to one embodiment includes a controller that switches between a boosting operation in a boost circuit and a pulse-width modulation operation in a single-phase inverter. The controller modifies an output from a voltage detection filter based on a delay compensating value for compensating a detection delay introduced by the voltage detection filter, when switching is performed the boosting operation in the boost circuit to the PWM operation in the single-phase inverter.

Abstract: A power conversion device including a power conversion portion that switches direct current voltage supplied by a positive line and negative line of a direct current power supply with a semiconductor switching element, and outputs converted voltage, is such that a plurality of interline capacitors are connected in parallel between the positive line and negative line, the capacitance of the plurality of interline capacitors is of a value that becomes smaller the nearer to the power conversion portion the position in which the interline capacitor is connected, and the capacitance of the interline capacitor with the smallest value of capacitance is set to a value greater than that of the capacitance between main electrodes when a direct current voltage is applied to the switching element used in the power conversion portion.

Abstract: An apparatus for compensating for a torque for a current order of a driving motor includes: a current order generator configured to: i) receive a torque order (Tref*), ii) generate a magnetic flux-based current order map using a generated driving point ratio (1/?max), and iii) generate a current order using the generated current order map; and an iron loss torque compensator configured to extract an iron loss torque compensation value for the generated current order and a speed (Wrpm) of the driving motor.

Abstract: According to an exemplary implementation, an integrated circuit (IC) includes a logic circuit monolithically formed on the IC. The logic circuit is configured to generate modulation signals for controlling power switches of a power inverter. The logic circuit generates the modulation signals based on at least one input value. The IC further includes a voltage level shifter monolithically formed on the IC. The voltage level shifter is configured to shift the modulation signals to a voltage level suitable for driving the power switches of the power inverter. The logic circuit can be a digital logic circuit and the input value can be a digital input value. The IC can also include a sense circuit monolithically formed on the IC. The sense circuit is configured to generate the input value.

Abstract: A motor control system for determining a reference d-axis current and a reference q-axis current is provided. The motor control system includes a motor, a DC power source and DC input lines, and a current command controller. The DC power source generates a bridge voltage across the DC input lines. The current command controller is configured to monitor the bridge voltage and a torque reference command. The current command controller is configured to calculate the reference q-axis current based on a torque reference command. The current command controller is configured to calculate the reference d-axis current based on a magnitude of the reference q-axis current.

Abstract: A method is provided for controlling the current intensity of the electric current flowing through an inductive consumer, the consumer being connected in series to a switching device and a current measuring unit, and in parallel to a free-wheeling element, and the switching device being activated for adjusting the current intensity during a pulse width modulation period.

Abstract: In a torque ripple suppression control effected by a periodicity disturbance observer, it is necessary to consider plant fluctuation and fluctuation of plant characteristics caused by over time usage. Thus, improvement for robustness to an identification model error has been required.

Abstract: Systems, apparatus, and methods detect a current sensor error in an FOC electric machine system. A voltage command is monitored to detect the presence of an ac component that indicates that an error has occurred at a current sensor. For example, a sensor fault detection module can be configured to determine the deviation between an actual voltage command and an ideal voltage command to provide a complex deviation vector. By transforming the deviation vector to a reference frame rotating at the fundamental frequency of the command voltage, a dc component of the positive and negative sequences can be filtered, and their amplitudes determined. Error detection can be based on the total amplitude of the fundamental component, determined by positive and negative component amplitudes. Sensor error detection enables an FOC system to operate with two current sensors, rather than three, and provides a dedicated fault diagnostic for a current sensor.

Abstract: An induction motor controller is provided. The induction motor controller includes a first module that derives a commanded stator voltage vector, in a stator flux reference frame, via a rotor flux regulator loop and a torque regulator loop, which process at least partially in the stator flux reference frame. The induction motor controller includes a second module that processes the commanded stator voltage vector to produce AC (alternating current) power for an induction motor.

Abstract: A motor controller includes a square wave voltage generator and adding circuitry for adding the square wave voltage to a first drive voltage that is connectable to the stator windings of a motor. A current monitor for monitoring the input current to the motor as a result of the square wave voltage. A device for determining the position of the rotor based on the input current.

Abstract: When a command frequency to a rotating electric machine is included in an inverter lock frequency band, a frequency switching section switches the command frequency to a frequency outside the inverter lock frequency band by changing a slip frequency command value. In response to this, a torque command change section changes a torque command to a second rotating electric machine other than a first rotating electric machine of which the slip frequency is changed such that a torque fluctuation caused by the change of the slip frequency command value is canceled out.

Abstract: The present invention relates to a method (30) for actuating an electric machine (14) in the motor starting mode by means of a power electronic system (10), in particular for application in a motor vehicle, wherein the power electronic system (10) has a multiplicity of controllable power switches which are designed to supply the electric machine (14) with electric current (l_s), wherein a total amount of energy (50) which is required to reach a predefined rotational speed (n_crit) and a time period (t—0) for reaching the predefined rotational speed (n_crit) is estimated (38), wherein a setpoint torque (M) for starting the electric machine (14) is determined (42) on the basis of the estimated total amount of energy (50) and the estimated time (t—0), and wherein the power electronic system (10) is actuated (46) in accordance with the setpoint torque (M).

Abstract: A vehicle includes a motor generator generating driving power for running, and an ECU. The ECU performs driving power variation operation on the motor generator in which the motor generator is switched between a first state (acceleration running) and a second state (inertial running) when power requested by a user varies within a prescribed range to run the vehicle. In the first state, the motor generator generates driving power. In the second state, the motor generator generates driving power smaller than the driving power in the first state. The ECU controls the motor generator in such a manner that the driving power during the acceleration running has a non-rectangular shape. As a result, gradual variation in driving power can be provided at the time of switching between the acceleration running and the inertial running, to improve drivability.

Abstract: Brushless direct-current (“BLDC”) motor and control for a power tool. A BLDC motor of a power tool is controlled in either a pulse-width modulation (“PWM”) commutation mode or a centerline commutation mode. When the motor is rotating slowly, the motor is operated using PWM commutation. When the motor is rotating at a speed greater than a threshold speed value, the operation of the motor is transitioned to the centerline commutation mode. When operating in the centerline commutation mode, the high-side field-effect transistors (“FETs”) and low-side FETs can each be used for motor speed control. By switching between speed control using the high-side FETs and speed control using the low-side FETs, the heat generated by freewheeling currents can be approximately evenly distributed among the high-side and low-side FETs.

Abstract: A motor control circuit and associated techniques can drive an electric motor in a start-up mode of operation followed by a normal mode of operation. The motor control circuit and techniques can receive a selection signal provided by a user that can select one of a plurality of sets of parameter values that determine characteristics of drive signals applied to the motor during the start-up mode of operation. The motor control circuit and associated techniques can synchronize operation between the start-up mode of operation and the normal mode of operation.

Abstract: A control device for controlling a three phase AC motor with an inverter includes: a current acquisition device for a current of the motor; a rotation angle acquisition device for a rotation angle of the motor; a current estimation device for a current estimated value; a first voltage command value operation device for a first voltage command value; a voltage command reference value operation device for a voltage command reference value; a second voltage command value operation device for a second voltage command value; a control mode switching device for first and second control modes generating a drive signal of the inverter based on the first and second voltage command value, respectively; and a number-of-revolutions operation device. When the revolution number is more than a threshold, the first control mode is selected. When the revolution number is not more than the threshold, the second control mode is selected.

Abstract: A method of controlling an output voltage of an inverter driving an electric motor may include removing harmonic components of an output current, which is output to the electric motor, by using a low pass filter and obtaining a fundamental component of the output current; calculating a current total harmonic distortion by using the fundamental component of the output current; comparing the current THD with a reference current THD; determining a pulse width modulation method to be changed from a first modulation method for reducing the harmonic components of the output current to a second modulation method for reducing a switching frequency of the inverter if the current THD is less than the reference current THD, the PWM method modulating a pulse width of a control pulse signal for controlling the output voltage of the inverter; and/or generating the control pulse signal based on the determined PWM method.

Abstract: In a system, a triangular carrier wave is compared in magnitude with first and second two-phase modulated command signals. Based on a result of the comparison, on-off operations of the high- and low-side switching elements of two phases of a three-phase inverter corresponding to the first and second two-phase modulated command signals are performed while the high- and low-side switching elements of the remaining phase of the three-phase inverter is fixed to be on or off. A value of a current flowing through a first or second bus connected between a DC power source and the three-phase inverter is measured when a local peak of the triangular carrier signal occurs while none of the high-side switching elements of all the three-phases are on or none of the low-side switching elements of all the three-phases are on.

Abstract: A driver circuit for driving an electrical load includes an input terminal pole connecting the driver circuit to an AC voltage source, an output terminal pole connecting the driver circuit to the load, a rectifier circuit connected to the input terminal pole for converting an AC voltage into a pulsating DC voltage, and a control element connected to the rectifier circuit and to the output terminal pole. The control element has a switch and a controller, the controller switching the switch on and off by means of a pulse train signal, wherein an electrical output value of the driver circuit is adjustable by switching the switch. The controller is configured to vary at least one time-based value of the pulse train signal within one period of the pulsating DC voltage such that a driver current is adjusted at the output terminal pole having a defined waveform within the period.

Abstract: A motor controlling apparatus including an inverter, a voltage detector, a rotational speed detector, a command value calculating component, an inverter controller, a state detector and an offsetting component. The inverter converts direct-current power to alternating-current power supplied to a motor. The voltage detector detects a direct-current voltage, and the rotational speed detector detects a rotational speed of the motor. The calculating component calculates current and torque command values, and motor rotational speed. The controller provides a control signal to control the inverter based on the current command value. The state detector detects a control state of the inverter, and the offsetting component offsets the detected voltage or rotational speed by an offset amount. The calculating component modifies the current command value based on the offset detected voltage or rotational speed to increase on a negative side a d-axis current command value included in the current command value.

Abstract: A generator system includes a generator and a generator control unit (GCU). The GCU is connected to monitor and regulate the generator output voltage. The GCU includes a protection signal processor that receives monitored generator voltages and executes software to detect an overvoltage condition. The GCU further includes redundant, hardware based overvoltage detection that detects a peak voltage value associated with the monitored generator voltage and includes a fast overvoltage detection circuit that generates a first overvoltage fault signal if the peak voltage value is greater than a first threshold value and includes an inverse overvoltage detection circuit that generates a second overvoltage fault signal if the peak voltage value is greater than a second threshold value for a duration of time that varies with a magnitude of the peak voltage value.

Abstract: In a system for driving an inverter, a superimposing element superimposes, on an output voltage of the inverter. The high-frequency voltage signal is correlated with a measured high-frequency component value of a current flowing in the rotary machine. A calculating element calculates a rotational angle of the rotary machine based on the measured high-frequency component value. A dead-time compensating element shifts a start edge and an end edge of an on duration for each of first and second switching elements of the inverter by a preset same time to compensate for an error due to dead time. A current manipulating element manipulates a current flowing in the rotary machine to maintain an accuracy of calculation of the rotational angle.

Abstract: A method for minimizing power losses in an alternating current (AC) machine is provided. The method includes determining a first rotor flux signal based on signals of voltage and current inputs to the AC machine, and extracting a ripple component of the rotor flux signal. The method further includes determining a power compensating value that corresponds to a stored energy value of the AC machine, determining a second rotor flux signal that serves to minimize power losses, and providing the second rotor flux signal to a power inverting unit that adjust accordingly the voltage and current input signals provided to the AC machine.

Abstract: A system and method for controlling an adjustable speed drive (ASD) to decelerate an AC load during a generating mode of operation is disclosed. The ASD includes a capacitor and an inverter coupled to a DC link. A current sensor system is coupled to an output of the inverter. The ASD further includes a control system programmed to calculate an energy of the capacitor, generate a reference power using the calculated capacitor energy, and calculate a feedback power from realtime current signals received from the current sensor system. The control system compares the feedback power to the reference power, defines a frequency offset based on the comparison, generates a speed command using the frequency offset, and outputs the speed command to the inverter to maintain a smooth DC link voltage during deceleration.

Abstract: Single-phase voltage operation techniques are provided for a three-phase drive system. A drive system may include a rectifier configured to couple to a three-phase AC voltage source. The rectifier may be configured to convert AC voltage from the three-phase AC voltage source to a direct current (DC) voltage. The drive system may also include a controller configured to send a plurality of switching signals to a plurality of switches in the rectifier such that the plurality of switching signals minimizes a current provided to the rectifier when only a single-phase of the three-phase AC voltage source is available.

Abstract: A method of driving an alternating-current (AC) motor while periodically obtaining a rotator angle of the AC motor. The method includes: (a) driving the AC motor by a dS-axis voltage, which is a voltage for an exciting current in a stationary reference frame, and a qS-axis voltage, which is a voltage for generating a rotational force in the stationary reference frame, while sequentially applying different dS-axis voltages and different qS-axis voltages to the AC motor in a control injection period; and (b) obtaining a rotator angle by a dS-axis voltage value, a qS-axis voltage value, a dS-axis current value, and a qS-axis current value in the control injection period.

Abstract: A method for estimating a torque of a three-phase motor for a vehicle includes measuring a respective current strength in at least two of three phase lines, wherein the three-phase motor is supplied with power by a converter, and wherein the three phase lines lead from the converter to the three-phase motor of the vehicle, measuring a respective voltage at each of the three phase lines, determining a rotating field frequency as a function of the measured current strengths or the measured voltages; and determining an estimated value for the torque as a function of the measured current strengths, the measured voltages and the determined rotating field frequency.

Abstract: An adjusting device for rotor blades of a wind power plant is disclosed. An AC motor is provided for adjusting the angle setting of the rotor blades. An input serves for receiving an input alternating current. A frequency converter is provided for generating a second alternating current having a second frequency, wherein the second alternating current drives the AC motor. Additionally, a DC voltage source and an inverter are provided for converting the voltage provided by the DC voltage source into an alternating current for the AC motor. The inverter is thereby separated from the frequency inverter.

Abstract: A system and method for controlling an adjustable speed drive (ASD) to decelerate an AC load during a generating mode of operation is disclosed. The ASD includes a capacitor and an inverter coupled to a DC link. A current sensor system is coupled to an output of the inverter. The ASD further includes a control system programmed to calculate an energy of the capacitor, generate a reference power using the calculated capacitor energy, and calculate a feedback power from realtime current signals received from the current sensor system. The control system compares the feedback power to the reference power, defines a frequency offset based on the comparison, generates a speed command using the frequency offset, and outputs the speed command to the inverter to maintain a smooth DC link voltage during deceleration.

Abstract: A synthetic space vector modulation method and device for controlling a voltage source inverter and load is provided. The device and method comprise a variable frequency oscillator (VFO), a center-aligned pulse-train signal generator, a modulo-N counter, and a three-phase time division multiplexer. The VFO outputs a square wave to the modulo-N counter and a triangle wave of the same frequency to the center-aligned pulse-train signal generator, the outputs of the center-aligned pulse-train generator and the modulo-N counter are sent to the three-phase time division multiplexers, and after leaving the multiplexers, and before being sent to the VSI controller's load each positive and each negative output of the multiplexing phase is sent to a turn-on delay. The present innovation makes VSI controller acquisition and repair almost as simple as buying and repairing a transistor radio.

Abstract: Alternating current electric induction motor, in particular a motor (12-22) which is fed by a frequency variator, comprising a casing (4) which supports a rotor (9) by means of roller bearings (8) and which supports a stator (13) with a coaxial ring-shaped core (16) made of a magnetic material, characterized in that the stator (13) is provided with an auxiliary closed loop toroidal winding (20).

Abstract: A motor control method comprises: inputting a PWM signal into a control unit for the control unit to obtain a direction command and a speed command by an identification rule, and generating a control signal according to the direction and speed commands by the control unit; and generating a driving signal according to the control signal by the driving unit for driving a motor to operate according to the direction and speed commands.

Abstract: A control device controls an inverter controlling an output of a motor by PWM control. The control device calculates a reference frequency based on a torque and a rotation speed of the motor, calculates a random coefficient using two data tables, and calculates, as a random frequency, a value obtained by adding, to a reference frequency, a value obtained by multiplying a prescribed width by the random coefficient. The control device calculates control limit lines based on the rotation speed of the motor, and corrects the random frequency so as to fall within a range that is higher than the control limit line and lower than the control limit line. The control device generates a carrier signal having a random frequency as a carrier frequency.

Abstract: An inverter device of a rotating electrical machine drives a multiphase rotating electrical machine having the variable number of rotations using a switching element provided for each phase. An example of the inverter device of the rotating electrical machine includes: a frequency setting unit for determining and setting a carrier frequency of a carrier signal for use in driving the switching element for each phase depending on the state of each phase of the rotating electrical machine for each specified electrical angle obtained by equally dividing a cycle of an electrical angle; and a signal generation unit for generating a drive signal for drive of the switching element of each phase using the carrier signal of the carrier frequency set for each phase by the frequency setting unit. The carrier frequency of each phase is an integral multiple of the phase voltage frequency at the specified electrical angle.

Abstract: In order to lower electromagnetic noise, normally, a carrier frequency of a inverter or controlling drive of a motor mounted on an electrically powered vehicle is changed periodically or randomly within a first frequency range set in advance, as the time elapses. While a vehicle speed is low, the carrier frequency is changed periodically or randomly within a second frequency range set in advance to be wider than the first frequency range and to be equal in central frequency to the first frequency range, as the time elapses. The second frequency range is set to include a resonant frequency of a specific mechanical oscillation system higher in electromagnetic noise generated at a natural resonant frequency, among a plurality of mechanical oscillation systems formed by equipment mounted on the electrically powered vehicle. On the other hand, the first frequency range is set not to include the resonant frequency.

Abstract: A method of controlling an electrical machine that includes exciting a phase winding with a supply voltage, and freewheeling the phase winding when current in the phase winding exceeds a threshold. The threshold is then adjusted in response to changes in the supply voltage and/or the speed of the electrical machine. Additionally, a control system that implements the method and an electrical machine comprising the control system are described.

Abstract: In a system, a superimposing element sets a command value vector of a high-frequency voltage signal and superimposes the high-frequency voltage signal with the command value vector on an output voltage of an inverter. The high-frequency voltage signal has a frequency higher than an electrical angular frequency of a rotary machine. The command value vector is correlated with a measured high-frequency component value of a current signal flowing in the rotary machine. A calculating element calculates a rotational angle of the rotary machine based on the measured high-frequency component value of the current signal flowing in the rotary machine. A reducing element controls at least one of the inverter and a direct voltage power supply to reduce a difference due to the dead time between the command value vector and a vector of a high-frequency voltage signal to be actually superimposed on the output voltage of the inverter.

Abstract: A system, method and computer program product for monitoring including detecting internal faults especially inter-turn faults of a synchronous generator and thus protecting the synchronous generator. The synchronous generator includes a winding for each phase of a power network, a terminal for each phase arranged on a terminal side of the synchronous generator, and connected to the respective winding, the terminals on the terminal side are connected to an electrical power network, and the synchronous generator is arranged to input power to the electrical power network by means of the terminals.

Abstract: Power conversion systems with active front end converters for example motor drives and power generation systems for distributed energy sources are presented with adaptive harmonic minimization for grid-tie converters for minimized or reduced total harmonic distortion in the line current spectrum including the source harmonic current, the load harmonics and the PWM harmonics.

Abstract: A motor driving apparatus is disclosed herein and includes a control unit, a soft-start unit and an output unit. When power-up or lock release situation, an external PWM driving signal is inputted to the soft-start unit, the soft-start unit generates an internal PWM driving signal and a power-up initial signal; after the power-up initial signal is generated, the control unit transmitting a motor rotation signal to the soft-start unit; when the soft-start unit counts a plurality of the motor rotation signal, the soft-start unit selects the external PWM driving signal or the internal PWM driving signal to output to the output unit.

Abstract: A system includes a target speed module and a pulse-width modulation (PWM) control module. The target speed module is configured to provide a first waveform based on a first speed setting for a motor. A start of a first cycle of the first waveform corresponds to at least one of a first current or a first voltage. The PWM control module is configured to shift a phase of the first waveform by a torque angle adjustment value to generate a second waveform. A start of a first cycle of the second waveform corresponds to at least one of a second voltage or a second current. The second voltage is greater than the first voltage, and the second current is greater than the first current. The PWM control module is configured to control the motor based on the second waveform.

Abstract: A drive control device is provided with a physical amount detection unit which detects the physical amount pertaining to the output of a motor, a rotational frequency determination unit for determining whether the rotational frequency of the motor is equal to or greater than a base rotational frequency, a threshold value selection unit for selecting a threshold value for the physical amount in accordance with the determination result of the rotational frequency determination unit, and a rotational frequency control unit for controlling the rotational frequency of a rotating shaft in accordance with the magnitude relationship between the detected physical amount and the selected threshold value.

Abstract: The invention relates to methods and devices for monitoring and correcting a sensorless rotor position detection in permanently excited motors, comprising a control device and a current converter. The invention is especially characterised in that the ambiguity of the rotor position determined from the inductance ratios of the motor, in permanently excited motors, can be resolved in a simple manner without a sensor, and a defectively determined angle can be corrected as required. To this end, during the operation of the motor, the rotor position is detected by means of an inductance-based detection device. Furthermore, the rotor position is monitored in relation to the ambiguity of the inductance-based signals by means of a monitoring/correcting device, and where necessary, an occurring angle error corrected, the currents in the motor being modified.

Abstract: A method for pulse width modulation control of a multiple phase drive includes identifying at least one phase from the plurality of phases for the drive as eligible for clamping to one of a plurality of extreme power supply voltages, selecting a phase of the eligible phases having a largest magnitude driving current, determining a first offset signal as a difference between a control signal level for the selected phase and an extreme control signal level corresponding to one of the extreme power supply voltages, limiting a rate of change of the first offset signal to form a second offset signal, and determining a modified control signal for each of the phases for the drive including forming for each of a plurality of the phases a combination of the second offset signal and a control signal level for the phase to determine the modified control signal for the phase.

Abstract: A method for pulse width modulation control of a multiple phase drive includes identifying at least one phase from the plurality of phases for the drive as eligible for clamping to one of a plurality of extreme power supply voltages, including excluding from the eligible phases those phases with intermediate control signal levels and excluding phases according to a proximity criterion on the control signal levels. A phase is selected from the eligible phases. An offset signal is determined as a difference between a control signal level for the selected phase and an extreme control signal level associated with one of the plurality of extreme power supply voltages. A modified control signal is determined for each of the phases, by forming a combination of the offset signal and a control signal level for each phase to determine the modified control signal for each phase.

Abstract: A combination module for an appliance includes a transmission selector mechanism adapted to selectively operate transmission shift structure of the appliance, and a speed sensor mechanism adapted to sense the operative speed of a motive element of the appliance. In one example, the combination module further includes a single electrical connector adapted to electrically couple the transmission selector mechanism and the speed sensor mechanism to control circuitry of the appliance.

Abstract: A DC voltage value from a DC voltage detection section is input directly to a voltage correction section without passing through a compensator or a filter. Therefore, even when rapid voltage change occurs, such as short power interruptions, instantaneous voltage drop and return from instantaneous voltage drop, the voltage correction section can quickly perform the correction operation in response to the rapid voltage change. Since the amount of link resonance compensation is limited by the limitation section to a certain range, it is possible to prevent the amount of link resonance compensation from fluctuating excessively upon rapid voltage change. Since the amount of link resonance compensation which is limited by the limitation section to a certain range is input to one compensator that has an appropriate control band, among all control calculation sections, the response does not have to be unnecessarily fast, thus realizing a stable control.

Abstract: An AC-AC power converter supplies AC power to an AC motor having a plurality of motor windings and a case connected to a ground. The AC-AC power converter architecture includes an asymmetric phase shift autotransformer/rectifier unit (ATRU) that converts an AC input to a DC output, wherein the asymmetric phase shift ATRU generates a common-mode AC voltage across the asymmetric phase shift ATRU. The common mode voltage is diverted to ground through motor case parasitic capacitance via a common-mode voltage pull-down circuit connected between each phase of the ATRU AC input and the ground.

Abstract: A motor drive system includes an inverter that supplies power to a three-phase motor, and a control unit that, when first stopping and then commencing supply of alternating current to three phases of the three-phase motor, switches from first control to third control and then to second control. The first control places switching elements in the inverter in a non-conduction state, the second control is a PWM control of the switching elements, and the third control places and keeps a switching element of each of an upper arm and a lower arm in the conduction state until commencement of the supply of current. The upper arm corresponds to a phase through which current flows in a direction entering the motor upon commencement of the supply, and the lower arm corresponds to a phase through which current flows in a direction exiting the motor upon commencement of the supply.