Abstract: A power conversion device is configured to output, to each of two inverters configured to invert a DC voltage output from a DC power supply to three-phase AC voltages, on/off signals for switching on and off respective semiconductor switching elements of each of the inverters so that, out of a plurality of voltage vectors defined so as to correspond to patterns of the on/off signals, the second closest voltage vector and the third closest voltage vector in phase to a voltage command vector that is based on a voltage command value calculated for each of the inverters are formed.

Abstract: A method for controlling an electric motor, the method comprising receiving a command to place the electric motor in a short circuit mode; varying a limit to an available pulse width modulation depth for controlling current flow in the electric motor to a predetermined value over a predetermined time period or at a predetermined rate of change; wherein upon the pulse width modulation depth limit being varied to the predetermined value placing the electric motor in the short circuit mode.

Abstract: The control device includes: a unit for receiving, for a time period, phase voltage setpoints forming a setpoint vector in vector space; a unit for selecting at least N+1 states of the inverter which are associated, respectively, with at least N+1 predetermined vectors (M1 . . . M27) defining a volume in the vector space (Esp) containing the setpoint vector; a unit for controlling the inverter, over the time period, in order to place it successively in the selected states so that it substantially applies, on average over the time period, the phase voltage setpoints. The at least N+1 states of the inverter are selected from among groups of at least N+1 states of the inverter, the at least N+1 states of the inverter of at least one of the groups being associated, respectively, with at least N+1 predetermined vectors (M1 . . . M27), at least N of which are formed by predetermined zero-sum phase voltages and at least one of which is formed by predetermined nonzero-sum phase voltages.

Abstract: A boost circuit is arranged to reduce rise and fall times of pulsed power used for pulsed control operation of electric machines. Magnetic energy present in the electric machine at the end of a pulse is extracted by the boost circuit to reduce the pulse fall time. The energy is stored by the boost circuit and then applied at the beginning of a subsequent pulse to reduce the rise time. By reducing rise and fall times compared to not using such a boost circuit, machine efficiency is improved.

Abstract: A method for controlling an electric motor, implemented in a variable speed drive, the variable speed drive being connected to the electric motor through a transformer, the method including; executing an identification sequence of the transformer for determining gain data corresponding to an inverse function of a transfer function of the transformer; generating a transfer module based on said determined gain data; determining a start-up sequence of the electric motor to be implemented by the variable speed drive by executing the transfer module on a reference current path.

Abstract: This is to reduce electromagnetic noise while reducing a calculation load of a microcomputer. An inverter drive device according to the present invention switches a first control mode, a second control mode, and a third control mode on the basis of vehicle speed information in a motor control device that controls a power converter that drives a polyphase motor by a PWM pulse signal based on a carrier signal, the first control mode being for updating a command voltage signal to the power converter only on a ridge side or a trough side of the carrier signal, the second control mode being for updating a command voltage signal to the power converter both on a ridge side and a trough side of the carrier signal, and the third control mode being for updating a command voltage signal to the power converter only once of ridge-trough-ridge or trough-ridge-trough of the carrier signal.

Abstract: An object of the present invention is to reduce output voltage errors of an inverter circuit and stably control a motor until the motor reaches high speed rotation. An inverter device includes a PWM controller that generates a PWM pulse for converting DC voltage to AC voltage in accordance with an output request of a motor, and an inverter circuit that converts the DC voltage to the AC voltage with the PWM pulse generated by the PWM controller and drives a motor. The PWM controller changes the pulse width of the PWM pulse at predetermined timing on the upper side of the trapezoidal wave when the trapezoidal wave modulation using the trapezoidal wave is performed in the overmodulation region.

Abstract: Disclosed is a method for controlling phase currents of a plurality of three-phase inverters connected in parallel. The phase currents of each inverter are controlled by direct hysteresis current control wherein an actual current space vector for actual values of the phase currents of each inverter is maintained about a target current space vector within a hysteresis window. The measured current space vector of a first inverter is formed by all three phase currents of the first inverter. The actual current space vector of each additional inverter is formed from exactly two phase currents of the respective additional inverter under the proviso that all three phase currents of the additional inverters add up to zero. The selection of the two phase currents from which the actual current space vector is formed, is varied.

Abstract: A method is provided for controlling a transition between over-modulation and six-step pulse width modulation (PWM) modes in an electrical system having a polyphase electric machine driven by a polyphase output voltage of a power inverter. The method includes receiving input values via a PWM controller, including a holding angle, rotational speed of the electric machine, and present voltage angle of the power inverter. The method includes calculating a future voltage angle of the inverter using the input values and adjusting pulse widths of a baseline PWM pulse train based on a duty cycle of the power inverter. The power inverter output voltage is controlled during the transition using the adjusted baseline PWM pulse train, such that the transition is continuous. An electrical system includes the power supply, power inverter, electric machine, and the PWM controller, the latter of which is configured to execute the method.

Abstract: In a control apparatus, a controller performs comparison between a command voltage and a cyclic carrier signal to thereby perform one of pulse-width modulation upon each of first positive and negative peaks of the command voltage being within or identical to the corresponding one of second positive and negative peaks of the cyclic carrier signal, and single-pulse modulation upon each of the first positive and negative peaks of the command voltage being outside the corresponding one of the second positive and negative peaks of the cyclic carrier signal. The pulse-width modulation generates, for each cycle of the command voltage, plural drive pulses based on a result of the comparison. The single-pulse modulation generates, for each cycle of the command voltage, a single positive pulse and a single negative pulse for each cycle of the command voltage based on a result of the comparison.

Abstract: A control circuit reduces switching loss by periodically stopping switching elements, and reduces the difference between the time for which positive switching elements are in on state and the time for which negative switching elements are in on state. The control circuit includes a command value signal generator generating command value signals Xu1, Xv1, and Xw1 from line voltage command value signals Xuv, Xvw, and Xwu, and includes a PWM signal generator generating PWM signals by the command value signals Xu1, Xv1, and Xw1. The command value signals Xu1, Xv1, and Xw1 are continuously at “0” for a predetermined period, and are continuously at “2” for another period. This enables reducing the difference between the period for which the PWM signals are low and the period for which they are high.

Abstract: A powertrain for a vehicle includes a Y-wound generator, a Y-wound motor, a generator inverter, a motor inverter, and a traction battery. The Y-wound generator and Y-wound motor are coupled via each respective neutral terminal. The generator inverter is coupled between the Y-wound generator and a generator bus and the motor inverter is coupled between the Y-wound motor and a motor bus. The traction battery has a first terminal coupled to each neutral terminal and a second terminal coupled to bus terminals of the generator and motor bus.

Abstract: A method of control of an electric motor involves generation of an electrical control signal for the electric motor, the signal having a series of sequences of pulses, each pulse being defined by a width and a period. The ratio of width to period defines a mean electrical power provided to the electric motor by this pulse. The period of a pulse situated at an arbitrary position of a sequence of pulses is equal to the period of the pulse situated at that position of any other sequence of pulses of the series, and the period of each pulse is fixed in a pseudo random manner, such that the inverse of the fixed period lies above the audible acoustic spectrum. The number of pulses of each sequence is fixed so that the inverse of the sum of the periods of all the pulses lies below the audible acoustic spectrum.

Abstract: According to certain aspects, the present embodiments provide a solution for sampling and converting an analog signal at high frequencies but with low power consumption. In some embodiments, a low power, low resolution, AC coupled ADC is used to track the high frequency component of the analog input signal, in parallel with a high resolution ADC to sense the DC signal at a significantly lower sample rate. According to some aspects, the AC coupled ADC requires no reference or a low resolution reference. In these and other embodiments, a plurality of low resolution, low power ADCs having a high sampling rate may be time multiplexed together with a precision ADC at a low sampling rate.

Abstract: A method and system to improve backoff counter handling with relation to a clear channel assessment (CCA) process. The method and system improve a wireless medium availability by adjusting the backoff counter such that the processing of a preamble of a frame received during a backoff is taken into account. Received frames that fall between two CCA thresholds may require decoding of information in the preamble to assess whether the wireless medium is available. A portion of the preamble is decoded that identifies information utilized to determine whether the wireless medium may be considered to be busy. However, during this determination that requires the reading of the preamble of a received frame the backoff counter may be held or decremented even though the wireless medium status is unknown. The method and system provide a set of possible adjustments to the backoff counter to account for this uncertainty and the outcome of the CCA.

Abstract: A motor driving control device includes a motor driving unit to drive the motor, a rotational position detecting circuit for generating rotational position information, and a controller. The controller outputs, to the motor driving unit, a first drive control signal for controlling an adjustment at a time of energization switching to reduce resonance between a natural frequency of the motor and a rotational component of the motor based on the rotational position information when an actual rotational speed of the motor is equal to or higher than a predetermined rotational speed lower than a target rotational speed, and outputs, to the driving unit, a second drive control signal for controlling regular energization switching without performing the adjustment at the time of energization switching when the actual rotational speed is less than the predetermined rotational speed and a set duty is within an error range of a maximum value.

Abstract: A method (70) for controlling a multilevel regenerative drive (30) having a converter (32) and an inverter (34) is disclosed. The method (70) may include applying at least one of unipolar modulation and bipolar modulation to the converter (32), and applying at least one of unipolar modulation and bipolar modulation to the inverter (34). A control system (52) for a mechanical system (20) having a motor (28) is also disclosed. The control system (52) may comprise a converter (32) operatively connected to a power source (29), and an inverter (34) operatively connected to the motor (28) of the mechanical system (20). At least one controller may be in communication with the converter (32) and inverter (34), and may be configured to apply at least one of unipolar modulation and bipolar modulation to each of the converter (32) and the inverter (34).

Abstract: Disclosed is a device for controlling an inverter. The device achieves a minimum switching loss in a discontinuous modulation duration regardless of a power factor. The device includes: a command voltage transform unit configured for transforming each of 3 phases command voltages into each of pole command voltages using the DC stage voltage, a pulse width modulation index, a discontinuous modulation angle corresponding to a discontinuous modulation duration, and each phase difference between each of the 3 phase command voltages and each of 3 phases output currents of the inverting module; and a controller configured for generating a control signal based on a comparison between each pole command voltage and a triangular carrier wave, wherein the control signal controls upper and lower switching elements of each phase leg.

Abstract: A gate driving circuit is connected to a main switching element. The gate driving circuit includes a gate resistor. The gate resistor includes a voltage controlled resistor of which a resistance value is able to be continuously changed. A switching power supply device includes a gate driving circuit, a main switching element, and a freewheeling diode connected in reverse parallel to the main switching element.

Abstract: A method of commutation in a matrix rectifier from an active vector to a zero vector includes two steps. A method of commutation in a matrix rectifier from a zero vector to an active vector includes three steps.

Abstract: A power switch apparatus for a power converter includes a semiconductor power switch and a gate drive unit connected to the semiconductor power switch for supplying gate drive signals to the semiconductor power switch to switch it on and off to cause the power converter to generate an alternating current voltage having a nominal operational frequency based on command signals received from a controller. The gate drive unit receives command signals based on the AC voltage to be generated and to alter the switching events of the semiconductor power switch by addition of a pre-defined jitter-like deviation to the gate drive signals such as to cause the power converter to generate an AC voltage having a modified operational frequency which partly and temporarily deviates from the nominal operational frequency by a pre-defined minimum percentage. A power converter comprising such a power switch apparatus is also disclosed.

Abstract: An inverter system includes a rectifier configured to convert a 3-phase AC voltage into a DC voltage, a DC link capacitor configured to smooth the DC voltage into a DC link voltage, an inverter unit configured to convert the DC link voltage into an AC voltage and to output the AC voltage to a motor, and a controller configured to control operation of the inverter unit. The controller performs control to switch the inverter unit to a zero vector when overload is applied during operation of the inverter unit.

Abstract: A control circuit reduces switching loss by periodically stopping switching elements, and reduces the difference between the time for which positive switching elements are in on state and the time for which negative switching elements are in on state. The control circuit includes a command value signal generator generating command value signals Xu1, Xv1, and Xw1 from line voltage command value signals Xuv, Xvw, and Xwu, and includes a PWM signal generator generating PWM signals by the command value signals Xu1, Xv1, and Xw1. The command value signals Xu1, Xv1, and Xw1 are continuously at “0” for a predetermined period, and are continuously at “2” for another period. This enables reducing the difference between the period for which the PWM signals are low and the period for which they are highl.

Abstract: The present invention relates to a control method for balancing a neutral point voltage of a three-level circuit, comprising obtaining the neutral point voltage through sampling, adjusting a duty ratio of a zero level in one phase to maintain balance of the neutral point voltage when an absolute value of the neutral point voltage is larger than a threshold value, and distributing duty ratios of positive and negative levels in the phase, such that an output voltage of switch bridge arm in the phase includes positive, negative and zero levels in at least one switch period. The present invention can be carried out in a three-phase four-wire system and a three-phase three-wire system. In the three-phase three-wire system, it may also be combined with zero sequence voltage injection to form a mixed modulation method, thereby acquiring more effective neutral point balance control performance, and reducing switch loss.

Abstract: A control system for actively damping an output of an adjustable speed drive (ASD) having a DC link thin film capacitor is programmed to calculate a d-axis damping coefficient and a q-axis damping coefficient for stabilizing an output of the ASD based at least on a voltage across the DC link thin film capacitor at a steady operating point. The control system is further programmed to extract d-axis and q-axis perturbations in d-axis and q-axis output currents of the ASD using a high pass filter, damp the d-axis perturbation and the q-axis perturbation with the d-axis damping coefficient and the q-axis damping coefficient, respectively, and calculate a damping frequency based on the damped d-axis perturbation and the damped q-axis perturbation. The control system is also programmed to damp an angle of rotation of a reference motor speed command for controlling the ASD using the damping frequency.

Abstract: Systems and methods are provided for regulating a power converter. An example system controller includes: a driver configured to output a drive signal to a switch to affect a current flowing through an inductive winding of a power converter, the drive signal being associated with a switching period including an on-time period and an off-time period. The switch is closed in response to the drive signal during the on-time period. The switch is opened in response to the drive signal during the off-time period. A duty cycle is equal to a duration of the on-time period divided by a duration of the switching period. One minus the duty cycle is equal to a parameter. The system controller is configured to keep a multiplication product of the duty cycle, the parameter and the duration of the on-time period approximately constant.

Abstract: Systems and methods are provided for regulating a power converter. An example system controller includes: a driver configured to output a drive signal to a switch to affect a current flowing through an inductive winding of a power converter, the drive signal being associated with a switching period including an on-time period and an off-time period. The switch is closed in response to the drive signal during the on-time period. The switch is opened in response to the drive signal during the off-time period. A duty cycle is equal to a duration of the on-time period divided by a duration of the switching period. One minus the duty cycle is equal to a parameter. The system controller is configured to keep a multiplication product of the duty cycle, the parameter and the duration of the on-time period approximately constant.

Abstract: A method is provided for braking a compressor of a refrigeration appliance, of an air conditioning appliance or of a heat pump in which the compressor has a brushless motor with windings and a controller for braking the motor. The controller is configured to brake the brushless motor by using a braking current in a controlled manner starting from an operating rotational speed, in which the braking current during the controlled braking is dependent on induced voltages determined before the controlled braking. The method for braking includes rotating the motor at an operating rotational speed, receiving a signal for decelerating, braking or slowing down, determining voltages induced in the windings and supplying a braking current having a decreasing frequency to the windings, in which the braking current during the braking is dependent on the previously determined induced voltages. A compressor and a refrigeration appliance having the compressor are also provided.

Abstract: A method of controlling an alternating current (AC) motor includes following steps: (a) providing a voltage to the AC motor, wherein the voltage is a pulse-width modulation (PWM) signal, which is represented by a voltage reference vector; (b) determining that the voltage reference vector is in a distortion region; and (c) in response to determining that the voltage reference vector is in the distortion region, modifying, via a controller, the PWM signal by updating the voltage reference vector every half switching period to avoid the distortion region.

Abstract: An embodiment of a control system for controlling operation of an electric motor includes a current command module configured to receive a torque command and output a current command, and a current controller module configured to generate a modulation index value based on the current command. The system also includes a signal generator configured to generate a voltage signal modulated via a pulse width modulation (PWM) scheme based on the modulation index value, the PWM scheme being a combination of a continuous PWM scheme and a non-continuous PWM scheme based on the modulation index value being greater than or equal to a first threshold value, the signal generator configured to output the voltage signal to the electric motor.

Abstract: A method of commutation in a matrix rectifier from an active vector to a zero vector includes two steps. A method of commutation in a matrix rectifier from a zero vector to an active vector includes three steps.

Abstract: A system is provided. The system includes a plurality of uninterruptible power supplies (UPSs), each UPS of the plurality of UPSs including an inverter, a ring bus, and at least one controller communicatively coupled to the plurality of UPSs, the at least one controller configured to control at least one bridge current in each UPS, the at least one bridge current controlled such that the inverter of each UPS operates in a partial current limiting regime between a full current limiting regime and a linear mode.

Abstract: A rotation controller for an AC electric motor includes a space vector generator, a current change ratio obtainer, and a rotational angle calculator. The space vector generator generates at least a first magnetic field in a first direction and a second magnetic field in a second direction crossing the first direction in a rotation plane of a saliency-exhibiting rotor. The space vector generator synthesizes the first magnetic field and the second magnetic field into a synthesized magnetic field. The current change ratio obtainer acquires a first current change ratio of a first current generated in the first direction in a stator and a second current change ratio of a second current generated in the second direction in the stator. The rotational angle calculator calculates a rotational angle of the saliency-exhibiting rotor based on at least the first and second current change ratios and the first and second directions.

Abstract: A high-side switching element is provided between a main output terminal having an intermediate potential and a high-side terminal. A signal transmission circuit includes a first point, a second point, a signal switching element, and a diode. The intermediate potential is applied to the first point. A referred potential between the low-side potential and the high-side potential is applied to the second point. The signal switching element has a first end connected to the first point and a second end, and is switched in accordance with a conversion signal. The diode is provided between the second point and the second end of the signal switching element and has a direction with which a forward current can flow by a voltage between the first point and the second point in a case where the intermediate potential is the low-side potential.

Abstract: A system and method for controlling a DC midpoint terminal voltage of a three level inverter is provided. The method includes receiving an input power signal at a three level motor controller system that includes a three level inverter, measuring, using a current sensor in the three level motor controller system, a DC current of the input power signal before the input power signal is provided to the three level inverter, and adjusting a zero-sequence inverter output voltage to adjust a midpoint voltage at the DC midpoint based on the measured DC current.

Abstract: A motor control system and associated method includes a transform component configured to receive current values associated with a motor being driven by the motor control system, and output rotating coordinate system values representing a flux generating component and a torque generating component of a current space vector. The motor control system and method further includes a control component configured to receive the flux generating component and the torque generating component of the current space vector, and generate motor control signals for driving the motor by performing a Cartesian to polar transform to obtain values associated with a rotating coordinate system followed by an angle addition to convert the rotating coordinate system values to values of a stationary coordinate system.

Abstract: A system for compensating one or more DC components in an electrical system includes one or more sensors for sensing the one or more DC components. The system also includes one or more DC component controllers for generating one or more reference signals from one or more signals received from the one or more sensors. In addition to this, the system also has one or more controllers for generating one or more firing pulses from the one or more reference signals received from the one or more DC component controllers and one or more valve configurations for charging one or more controllable branches to counterbalance the one or more DC components of the electrical system. A method for compensating one or more DC components in an electrical system is also provided.

Abstract: A rotating electrical machine control device with an electronic control unit that is programmed to: switch a modulation method between asynchronous modulation in which switching of the inverter is controlled by modulated pulses generated based on a carrier having a first carrier frequency which is not synchronous with rotation of the rotating electrical machine and synchronous modulation in which switching of the inverter is controlled by modulated pulses generated in synchronization with rotation of the rotating electrical machine, the switching of the modulation method between the asynchronous modulation and the synchronous modulation being performed according to an operating condition of the rotating electrical machine which includes at least a rotational speed of the rotating electrical machine.

Abstract: A power supply ECU executes turn-on current control for controlling a turn-on current It to a target value Itr by adjusting a drive frequency f, turn-on current It indicating an output current Io of an inverter at a rising of an output voltage Vo of the inverter. Target value Itr is set to fall within a range where a recovery current is not produced in the inverter. In the turn-on current control, when a startup frequency indicating drive frequency f at a startup of the inverter is fa0, the control unit adjusts drive frequency f to be more than or equal to fa0. When turn-on current It is larger than target value Itr, the control unit adjusts drive frequency f in the direction toward startup frequency fa0.

Abstract: The global synchronous pulse width modulation system includes main control unit and plurality of grid-connected inverters located at different geographical locations, wherein each grid-connected inverter is connected with a distributed power supply; each grid-connected inverter is connected with a grid through a point of common coupling; main control unit communicates with all grid-connected inverters through communication channels; main control unit receives information of grid-connected inverters and respectively sends a global synchronous signal containing global synchronous strategy to grid-connected inverters after determining global synchronous strategy; grid-connected inverters regulate the phases of their own pulse width modulation waves through global synchronous signal to enable pulse width modulation waves of grid-connected inverters to satisfy a phase difference of harmonic counteraction, so as to counteract harmonic current injected by grid-connected inverters into grid.

Abstract: A method of commutation in a matrix rectifier from an active vector to a zero vector includes two steps. A method of commutation in a matrix rectifier from a zero vector to an active vector includes three steps.

Abstract: Provided is a new control method that causes no time lag or hunting when a power conversion direction is reversed. The power conversion apparatus includes switching elements (S1 and S2) that alternately perform switching and are capable of reversing the power conversion direction without suspension, and an up/down counter register (RT) that has two different thresholds and selects counting up at a smaller threshold, counting down at a larger threshold, and holding of the value between the two thresholds. According to the value of the up/down counter register (RT), a gate pulse is generated to control the switching of the switching elements (S1 and S2).

Abstract: A motor-driven compressor includes an electric motor driven by a motor driver, which includes a switching element that converts DC voltage from a battery to AC voltage. A control unit controls the switching operation of the switching element. A temperature detector detects the temperature of the switching element. The control unit suspends the switching operation of the switching element when the temperature detected by the temperature detector rises to a temperature threshold. The temperature threshold includes a first temperature threshold, corresponding to a withstand temperature of the switching element, and a second temperature threshold, which is higher than the first temperature threshold. The control unit switches the temperature threshold from the first temperature threshold to the second temperature threshold when the control unit activates a field weakening control that reduces counter electromotive force generated by the electric motor.

Abstract: A feedback control system may include a feedback controller for controlling a plant using pulse density signals. The feedback controller may include a pulse density signal generator and a controller logic circuit. The pulse density signal generator may receive input command signals and generate signed or unsigned pulse density input signals. The controller logic may receive the pulse density input signals from the pulse density signal generator and feedback pulse density signals from the plant and may generate corresponding pulse density control signals for controlling the plant based on the input command signals. The controller logic may include a sign change logic, an addition circuit, and an optional amplifier circuit. The pulse density signal generator may also include rate transition circuits for ensuring that the pulse density input signals and the feedback pulse density signals are uncorrelated.

Abstract: Systems and methods are provided for regulating a power converter. An example system controller includes: a driver configured to output a drive signal to a switch to affect a current flowing through an inductive winding of a power converter, the drive signal being associated with a switching period including an on-time period and an off-time period. The switch is closed in response to the drive signal during the on-time period. The switch is opened in response to the drive signal during the off-time period. A duty cycle is equal to a duration of the on-time period divided by a duration of the switching period. One minus the duty cycle is equal to a parameter. The system controller is configured to keep a multiplication product of the duty cycle, the parameter and the duration of the on-time period approximately constant.

Abstract: A motor-driven compressor includes an electric motor driven by a motor driver, which includes a switching element that converts DC voltage from a battery to AC voltage. A control unit controls the switching operation of the switching element. A temperature detector detects the temperature of the switching element. A voltage detector detects DC voltage applied to the switching element from the battery. The control unit suspends the switching operation of the switching element when the temperature detected by the temperature detector rises to a predetermined temperature threshold. The control unit also reduces counter electromotive force generated by the electric motor. The temperature threshold includes a first temperature threshold, corresponding to a withstand temperature of the switching element, and a second temperature threshold, which is higher than the first temperature threshold. The control unit switches the temperature threshold between the first and second temperature thresholds.

Abstract: A power converting apparatus is provided. The power converting apparatus includes a power converter configured to output a voltage to a load, and a controller configured to output a PWM signal which is generated in response to a voltage command to the power converter. The power converter includes a plurality of switching elements driven based on the PWM signal. The controller is configured to generate the PWM signal such that a first period during which a zero voltage is outputted and a second period during which a non-zero voltage is outputted are adjusted according to the voltage command. The controller is allowed to output the PWM signal which is set such that one first period and one or more second periods exist within an updating cycle of the voltage command, to the power converter.

Abstract: A switching pattern determination unit in a control unit includes a modulation rate ensuring unit, a harmonic reducing unit, and a function combining unit, and sets a function f prescribing the relationship between each switching phase and a modulation rate, a function Y prescribing the relationship between each switching phase and the sum of squares of values obtained by multiplying a harmonic component of each order by a weighting coefficient of each order, and an evaluation function X formed from the function Y, the function f, and a weighting variable. Then, by a switching phase calculation unit and a switching pattern storage unit, each switching pattern according to each modulation rate m and each number of pulses is obtained and stored which ensures the modulation rate and reduces an addition value of harmonic components of respective orders.

Abstract: [Problem] An object of the present invention is to provide an electric power steering apparatus that has a 3-shunt control function to perform a 3-shunt PWM-control for raising a reliability of the apparatus and for improving a stability, and a 1-shunt control function to perform a 1-shunt PWM-control so as to continue an assist control when the 3-shunt control function is damaged. [Means for solving the problem] The electric power steering apparatus according to the present invention, having: a 3-shunt control function to perform a 3-shunt PWM-control with a first 3-phase detected current values based on down-stream 3-shunt; a 1-shunt control function to perform a 1-shunt PWM-control with a second 3-phase detected current values based on down-stream 1-shunt; and a switching function to switch from the 3-shunt control function to the 1-shunt function when a failure of current detection circuit system in relation to the first 3-phase detected current values is detected.

Abstract: A motor-driven compressor includes an electric motor driven by a motor driver, which includes a switching element that converts DC voltage from a battery to AC voltage. A temperature detector detects the temperature of the switching element. A voltage detector detects DC voltage applied to the switching element from the battery. A control unit suspends the switching operation of the switching element when the detected temperature rises to a temperature threshold. The control unit reduces counter electromotive force generated by the electric motor. The controller changes the temperature threshold such that the temperature threshold gradually increases from when the detected DC voltage is the highest voltage in the applicable voltage range of the battery to when the detected DC voltage is the lowest voltage in the applicable voltage range.