Abstract: Regulation of the active and reactive power of an induction machine in a coordinate system fixed on the winding, wherein a first regulator output variable is generated using a first regulator as a function of a setpoint variable deviation of the active power and a second regulator output variable is generated using a second regulator as a function of a setpoint variable deviation of the reactive power, feedback variables are added to each of the first and second regulator output variables, which are functions of at least one chronologically changing system variable of the induction machine, and a voltage or a current of the induction machine is determined as a manipulated variable without further regulation at least from the first and second regulator output variables added to the feedback variables. The feedback variables may linearize the regulation path and then allow restriction to only two simple regulators, e.g., two PI regulators. The regulation may be used in double-fed asynchronous machines.

Abstract: In an apparatus measuring constants of an induction motor, an inverter converts an inputted voltage command signal into a single-phase AC power and feeds the single-phase AC power to the induction motor, and a currert detector detects a current of the single-phase AC power fed to the induction motor. An apparatus controller generates a voltage command signal corresponding to an AC voltage as applied to the induction motor and outputs the voltage command signal to the inverter and gerates the voltage command signal and controls the inverter to feed the single-phase AC power having a frequency selected in a range equal to or higher than 0.006 Hz and equal to or lower than 1.5 Hz to the induction motor. A constant calculation controller calculates constants of the induction motor based on the voltage and current of the single-phase AC power fed to the induction motor.

Abstract: A variable speed drive for a three-phase electric motor, including a rectifier module supplying a rectified voltage from a single-phase alternating current network, a voltage step-up module supplying a regulated bus voltage, and an inverter module supplying a control voltage to the motor. The variable speed drive includes a hybrid power-factor correction device that drives the voltage step-up module and that includes a digital circuit including a voltage step-up module supplying a correction signal based on a measurement signal of the bus voltage and an analog circuit supplying a driver signal to the step-up module based on a measurement signal of the rectified voltage and based on the correction signal.

Abstract: Systems and methods that determine resonant frequencies of a motor system via employing an output of a velocity regulator. The velocity regulator enables the motor drive to command the rotation of the motor at predetermined rotations, by setting rotational speeds of the motor. The output of the velocity regulator can then be stored as a function of time, and a Fast Fourier Transform performed on such time data to obtain a frequency data and a signal power spectrum.

Abstract: An apparatus controlling a velocity of a motor having a rotor, includes a sensing velocity calculator sensing a rotation velocity of the motor, and calculating a sensing velocity on the basis of the sensed rotation velocity of the motor; a velocity estimator estimating an estimation velocity of the motor based on an information about a position error of the rotor; and a reference velocity calculator dividing an overall velocity period of the motor into a plurality of unit velocity periods based on a command velocity for controlling the rotation velocity of the motor, calculating a sum of the sensing velocity, the estimation velocity, and the command velocity after multiplying at least one of the sensing velocity, the estimation velocity, and the command velocity by a predetermined weight, and outputting the sum as a reference estimation velocity of the motor.

Abstract: A control device controlling a motor-driven four wheel drive vehicle, where either of front wheels and rear wheels are driven by an engine and the others are driven by an AC motor, is provided with an electric power generator driven by an engine to generate first three-phase AC power, a rectifier rectifying the first three-phase AC power, generated by the electric power generator, to second DC power and supplying the second DC power to a neutral point of the AC motor; and a first step-up and step-down inverter stepping up and converting the second DC power, supplied through the neutral point, to third three-phase AC power. The AC motor is rotationally driven by application of the third three-phase AC power from the first step-up and step-down inverter.

Abstract: The invention relates to methods and systems for modulating the supply voltage of an electric load, particularly an electric motor, fed by a bridge circuit, wherein the load is switched as a function of a predetermined setpoint value for the input current or the input power by means of power electronics to an intermediate circuit voltage. A modulation method is disclosed in which, instead of the winding current (or the winding currents in the case of multi-strand motors), the intermediate circuit current or the input power of the motor is used as the actual value for regulation. The switch-on times for the modulation of the motor voltage are predetermined at a set frequency by a controller, such as a microcontroller or a timer. The switch-off times are determined such that the average value of the intermediate circuit current corresponds to a predetermined setpoint value.

Abstract: Certain exemplary embodiments can comprise a system comprising an electric drive system for a machine. The system can comprise a rectifier adapted to convert AC power from an alternator to DC power. The system can comprise an inverter adapted to receive DC power from the rectifier and provide power to a traction motor and/or auxiliary devices. Certain exemplary embodiments can comprise a system and method for dissipating excess energy from a machine.

Abstract: Methods and systems are provided for capturing and saving motor drive information in a non-volatile memory to facilitate troubleshooting and motor fault analysis. The motor drive includes a power conversion system that provides electrical power to an electric motor and a control system providing a control input to the power conversion system, and an information capture system is provided with an information capture component to capture motor drive information and a non-volatile memory component to store the captured information.

Abstract: A device for conditioning power delivered to operate a motor is disclosed. The device includes a sealed housing having at least one input terminal extending through the housing and configured to receive an input power and at least one output terminal extending through the housing and configured to deliver an output power conditioned to power a motor coupled to the output terminal. The device also includes a filter inductor arranged in the housing and that has an input configured to receive the input power from the input terminal. The filter inductor output terminal has a tap that is extended through the housing to allow coupling of various external filter components, such as resistors capacitors and inductors. Accordingly, the filter inductor is configured to suppress voltage changes in the input power and deliver a filtered power to an output of the filter inductor.

Abstract: Methods and apparatus are provided for frequency scaling the PWM signal output of a controller/driver for an electrical device such as a BLDC motor. The apparatus comprises a number of multiple half-bridge assemblies, with each multiple half-bridge assembly connected to a respective phase winding of the motor. Each individual half-bridge assembly is operated within the frequency limit of its internal switching elements, but the composite output frequency of each multiple half-bridge assembly can be the product of the switching element frequency and the number of individual half-bridge assemblies in the multiple half-bridge assembly. High-speed torque loop control is implemented by synchronizing multiple DSP's with overlapping interrupts, so that the output pulse width of the PWM signal can be adjusted on a pulse-to-pulse basis. Moreover, the frequency scaling and pulse-to-pulse control processes can be achieved with standard off-the-shelf devices.

Abstract: This invention relates to the operation of a switching circuit, such as a bridge circuit. The invention provides a method of generating pulsed first and second switching signals for switching first and second switches of a switching circuit further comprising an output and that receives a DC signal of voltage +Vs, wherein switching of the first and second switches produces voltage pulses of +Vs, 0V and ?Vs at the output; the method comprising the steps of: receiving a voltage demand signal; and generating the first and second switching signals according to a rule that the first switching signal shall have a single pulse of a first determined width and the second switching signal shall remain in one state, the combination of the first and second switching signals producing an average voltage at the output being substantially equal to the demanded voltage.

Abstract: Apparatus for reconstructing the phase currents of a multiphase load driven by a multiphase inverter fed by a DC link and controlled by a PWM controller, the apparatus including a sensor in the DC link, first and second sampling arrangements for sampling the current in the DC link by obtaining an output from said sensor, the first sampling arrangement obtaining a first sample of the current in the DC link during a first time period corresponding to a first switching pattern of said multiphase inverter and storing said first sample; the second sampling arrangement obtaining a second sample of the current in the DC link during a second time period after said first time period and corresponding to a second switching pattern of said multiphase inverter and storing said second sample; an A/D converter for converting said first sample to a digital signal during a time period after said first time period and for converting said second sample to a digital signal during a following third time period.

Abstract: A system and method for controlling an inverter of a motor control unit includes a controller having a user interface configured to allow user selection of a waveform increment value or a waveform amplitude threshold. The controller also includes an integrator configured to receive the waveform increment value and generate a signal at least based on the waveform increment value. A logic circuit is configured to monitor the signal and reset the integrator when the signal reaches the waveform amplitude threshold to generate a waveform having a frequency-independent amplitude. A comparator compares the waveform to a modulating signal to trigger gating pulses delivered to an inverter to drive an associated motor.

Abstract: At least three alternative stiff current supply power converter topologies provide fixed current to a respective electric load such as a motor, or a non-inductive electric load using either a current source or a pseudo current source. The stiff current power converter topologies reduce the size of passive components within each of the topologies, thus reducing the overall packaging of each of the components and subsystems formed by each of the components. Each of the topologies have a stiff current source, a driver having power electronics formed therein to drive the associated electric load, wherein the stiff current source and the driver operate to deliver a stiff but controllable current to the electric load.

Abstract: Variable speed drive comprising a main rectifier module (10) including thyristors (K1, K2, K3) to power a main continuous bus (15) from an external power network (5), an inverter module (30) delivering a variable control voltage to an electric motor from the main bus (15), an auxiliary rectifier module (20) connected to the external power network (5), an electronic control unit (50) controlling the thyristors, a powering module (29) supplying the control unit (50) from the auxiliary rectifier module (20) and from the main rectifier module (10). According to the invention, a switching device (40) controlled by the control unit (50) is used to disconnect the powering module (29) and the auxiliary rectifier module (20).

Abstract: Certain exemplary embodiments can comprise a system comprising an electric drive system for a machine. The system can comprise a rectifier adapted to convert AC power from an alternator to DC power. The system can comprise an inverter adapted to receive DC power from the rectifier and provide power to a traction motor and/or auxiliary devices. Certain exemplary embodiments can comprise a system and method for dissipating excess energy from a machine.

Abstract: An electric four-wheel drive vehicle includes: an internal combustion engine; a generator for outputting DC electrical power; an inverter for converting DC electrical power, output from the generator, into AC electrical power; and an AC electric motor, which is driven by the inverter, for driving rear wheels. An electric motor controller controls the inverter, the AC electric motor, and the generator, according to torque instructions from a vehicle. Furthermore, in a case that the output of the AC electric motor becomes negative, and excess electrical energy is generated, the electric motor controller controls the current applied to said AC electric motor such that the loss in said AC electric motor exceeds the negative output of said AC electric motor. This enables the AC electric motor to absorb excess electrical energy in the form of thermal loss.

Abstract: Distribution of solar power in a solar DC source—variable frequency drive (VFD)—AC motor system is controlled by using solar irradiance. In addition, motor speed may be controlled as a function of available power, i.e. maximum power point tracking of motor speed, using solar irradiance.

Abstract: A motor driving apparatus is provided which can minimize ripple current flowing through a DC link capacitor, and downsize the motor driving apparatus. It synchronizes the frequency of the inverter carrier signal for driving an inverter with the frequency of the DC/DC converter carrier signal for driving a DC/DC converter, and carries out control in such a manner that the center of a period during which the input current of the inverter is zero and the center of a period during which the output current of the DC/DC converter is zero are matched.

Abstract: An electrical multiphase machine is proposed with a stator (3) including a winding (5;6) having at least two strands (51, 52, 53; 61, 62) for generating an electromagnetic field, each strand (51, 52, 53; 61, 62) belonging to a different electrical phase; furthermore with a setting device (4) which supplies each strand (51, 52, 53; 61, 62) with a phase current (Ia, Ib, Ic) or phase voltage (Ua, Ub, Uc) in each case as a setting parameter, said setting device (4) including) a separate power amplifier (41a, 41b, 41c, 41d) for each strand (51, 52, 53; 61, 62), so that the setting parameter can be regulated for each strand (51, 52, 53; 61, 62) independently of the setting parameters for the other strands (51, 52, 53; 61, 62) and at least one common connection point (VP) being provided to which at least two of said strands (51, 52, 53; 61, 62) are connected, and wherein an additional active control element (44) is provided for shifting the potential of said connection point (VP).

Abstract: An object of the invention is to provide a break detection method capable of lessening a delay of motor power line break detection. According to the invention, in a motor power line break detection method of an AC servo driver including a current detector and a torque controller, a torque current component 9 is extracted from a three-phase AC detected by current detector 4, 5, a comparison is made between a torque command 1 and the torque current component 9, and if the difference between the torque command and the torque current component exceeds a setup value 21, it is recognized that a motor power line is broken.

Abstract: In an electric car control apparatus for driving an induction motor, detection accuracy of a DC voltage is improved. A DC power supply device is provided which has a maximum potential terminal A, an intermediate potential terminal B, a minimum potential terminal C, an upstream side capacitor 6 between the maximum potential terminal A and the intermediate potential terminal B, and a downstream side capacitor 7 between the intermediate potential terminal B and the minimum potential terminal C. Also, an overvoltage suppression part is provided which includes a resistor 8 and a thyristor 9 between the maximum potential terminal A and the minimum potential terminal C.

Abstract: Motor drives, motor speed controllers, motor speed estimation systems, and methods are presented for controlling motor speed and for estimating motor speed, in which a speed estimate controller provides a rotor speed estimate based on a first error term from a torque-based MRAS component for a first range of motor speeds and based on a second error term from a rotor flux-based MRAS component for a second range of speeds.

Abstract: A method of protecting a frequency converter against overvoltage by controlling an AC motor during braking or during light load and a frequency converter, wherein the frequency converter is a voltage-controlled PWM frequency converter operating in single quadrant (1Q) and comprising at least one uncontrolled rectifier bridge (10) to be connected to a AC supply line (UL1, UL2, UL3), a direct-voltage intermediate circuit and at least one controlled inverter bridge (11) for feeding an AC motor (12) with an alternating voltage (Uu, Uv, Uw) of varying magnitude and frequency, in which method: the angle (??) between the output voltage vector (Us) and current vector (Is), i.e. the power factor, is measured, the angle (??) between the output voltage vector (Us) and current vector (Is), i.e. the power factor, is controlled on the basis of the measurement, and the angle (??) between the output voltage vector (Us) and current vector (Is), i.e.

Abstract: A method for controlling power supply to an induction motor is disclosed. A baseline reactive power on an induction motor during operation is initially measured. A new reactive power for offsetting the baseline reactive power is determined. Appropriate capacitance is then applied on the power lines for the induction motor in order to supply the new reactive power to the induction motor. After the appropriate capacitance has been added to the induction motor, an instant reactive power on the induction motor is measured. A determination is made whether or not the instant reactive power on the induction motor is equal to or less than the new reactive power. If the instant reactive power is equal to or less than the new reactive power, the instant reactive power on the induction motor is continuously measured. If the instant reactive power is greater than the new reactive power, the added capacitance is removed from the power lines, and a new baseline reactive power is obtained.

Abstract: A driving circuit of an AC fan motor has an AC to DC converter, a current detecting unit, a step-down divider, a motor driving unit, two windings each having many coils and a harmonic wave elimination unit. The AC to DC converter converts AC power to high voltage DC power. The motor driving unit is connected to the step-down divider to obtain low voltage DC power to operate. The two windings are directly connected to the AC to DC converter through the current wave detect unit to obtain the high voltage DC power. Therefore, the current wave detecting unit can response current changes of windings and then an operator can simulate present current wave of the windings to determine the present operating status of the AC fan motor.

Abstract: In a servo control apparatus constituted by a converter unit 3 for rectifying an AC power supply voltage to produce a DC power supply voltage, and a plurality of inverter units 5 for producing drive power supply voltages of motors from the DC power supply voltage, the servo control apparatus is provided with a power supply breaker 2 which is connected to the side of the AC power supply of the converter unit 3; and a ground fault detecting circuit 16 built in the converter unit 3. When a ground fault happens to occur, the servo control apparatus stops the operations of all of the inverter units 5 so as to cut off the breaker 2.

Abstract: A motor drive unit includes a controller, a voltage inverter, and a speed estimator. The controller is operable to generate at least one command signal for controlling a motor associated with the motor drive unit. The voltage inverter is operable to generate motor drive signals to be applied to the motor based on the command signal. The speed estimator is operable to estimate a speed of the motor when the voltage inverter is not providing the motor drive signals. The speed estimator is further operable to receive two-axis voltage measurements associated with the motor, determine flux angles for the motor based on the two-axis voltage measurements, and estimate the speed based on the determined flux angles.

Abstract: A vehicle electric drive system and a hybrid engine-motor type vehicle drive system realizing simplification and miniaturization of electric parts and, moreover, reduction in cost while maintaining performances can be provided. A part 1 of wheels is driven by an engine. The wheels are driven by a motor as necessary. The motor, a generator, and an accessory battery are connected to each other via a voltage step-up/step-down device. The voltage step-up/step-down device has a function of stepping up power of the battery and supplying the stepping up power to the motor, and a function of stepped down power of the generator and supplying the stepped down power to the battery and the accessories.

Abstract: Motor drives, motor speed controllers, motor speed estimation systems, and methods are presented for controlling motor speed and for estimating motor speed, in which a speed estimate controller provides a rotor speed estimate based on a first error term from a torque-based MRAS component for a first range of motor speeds and based on a second error term from a rotor flux-based MRAS component for a second range of speeds.

Abstract: An electric power converter, electric power conversion system and method that, without using a DC-DC converter, uses and allots the electric power of plural power sources while reducing the volume and losses. At least one phase of the motor is connected to plural power sources and generates and synthesizes pulses from output voltages of plural power sources so as to drive the multi-phase AC motor. A different phase of the motor is connected to one DC power source and generates pulses from the output voltage of the power source so as to generate a driving voltage for the multi-phase AC motor. This arrangement allows use/allotment of the power of plural power sources with a reduced number of semiconductor components.

Abstract: An apparatus and method for supplying a polyphase (AC) alternating current motor with driving voltages. A conversion unit is coupled to phases of the polyphase AC motor and includes a plurality of switching devices and includes, in at least one phase, a first switching device between a bus of an AC power supply and an output terminal, a second switching device between a bus of a direct current (DC) power supply and the output terminal, and a third switching device between a common bus for the AC power supply and the DC power supply and the output terminal. Driving voltages for the polyphase AC motor are generated by selecting a voltage from among voltages having potential values corresponding to the AC power supply and the DC power supply, and the selected voltage is used to operate a switch of the plurality of switching devices.

Abstract: A three-in-one AC servo drive includes a main console, a control module, a power module and a plurality of servo motors. A single drive can be connected to a plurality of motors. The power module and control module for the motors can be integrated to a single modular unit. Therefore, the redundant portion such as communication interface, display unit and I/O unit can be eliminated. The capacitor of the bus of the IGBT module can also be reduced, whereby the occupied space and cost can be reduced with less assembling time.

Abstract: A method of and apparatus for controlling an electric machine. The method can include using a controller to detect whether power is present at a first node of the controller, detect whether power is present at a second node of the controller, generate at least one signal based at least in part on the detection, and energize the electric machine using a detected power when the at least one signal indicates power is present at at least one of the first node, the second node, and a combination of the first node and the second node.

Abstract: A switching frequency multiplier inverter for low inductance machines that uses parallel connection of switches and each switch is independently controlled according to a pulse width modulation scheme. The effective switching frequency is multiplied by the number of switches connected in parallel while each individual switch operates within its limit of switching frequency. This technique can also be used for other power converters such as DC/DC, AC/DC converters.

Abstract: An electric power converter which has improved accuracy in compensation of a dead time. A motor driving system employing the electric power converter is also provided. A power module includes a plurality of switching devices connected in series and converts DC power to AC power. A control circuit produces a voltage command value in accordance with a control command inputted from the exterior, and produces gate signals to drive the switching devices of the power module corresponding to a final voltage command value which is obtained from the voltage command value with dead time compensation. A dead time compensation logic circuit calculates a final dead time compensation voltage based on a change rate of the voltage command value, a gain (dead time compensation voltage value), and a polarity of a current, the gain being calculated from a DC voltage value supplied to the electric power converter, a dead time, and a switching frequency.

Abstract: A voltage source converter with a line-side diode rectifier, a load-side inverter with an electronic circuit, a power supply for the electronic circuit, and a slim DC link with a DC link capacitor is described. The slim DC link connects a DC output side of the line-side diode rectifier with a DC input side of the load-side inverter. A buffer capacitor is connected across the power supply, and a decoupling diode and a current limiting circuit are electrically connected in series with the buffer capacitor. The serially connected buffer capacitor, decoupling diode and current limiting circuit are connected in parallel with the DC link capacitor. This arrangement results in a voltage source converter that has an improved service reliability even in unstable power grids, without adding circuit complexity to the line input.

Abstract: A method and a system for controlling the mains bridge of a four-quadrant PWM frequency converter provided with a direct-voltage intermediate circuit when power is flowing into the supply network. The mains bridge includes a controlled mains bridge (INU) for rectification of the mains voltage to produce a DC intermediate-circuit direct voltage (UDC) consisting of arms conducting during the positive and negative half cycles of the phase voltage of each phase of the supply network, each arm having a switch unit formed by a diode (D1–D6) and a power semiconductor switch (V1–V6), e.g. an IGBT, connected in inverse-parallel with it.

Abstract: A method of and system for identifying the position of magnetic poles of a rotor of a multi-phase electrical machine relative to a stator of that machine is disclosed. The method includes the steps of applying a voltage pulse to stator windings of each phase, sensing current flow in the stator windings of each phase due to the application of the voltage pulse to the respective stator windings and determining the position of the magnetic poles of the rotor relative to the stator using the sensed current flow in the stator windings of each phase. The method is characterized in that the phases of the stator windings are star-connected at a neutral junction and the voltage pulse is applied to the stator windings of each phase in parallel.

Abstract: An apparatus for controlling a motor in a washing machine, which includes a speed sensor for measuring speed of the motor, and a controller that compares the measured speed with a target speed to estimate a motor power applied to the motor, adjusts a running rate of the motor according to the comparison, and controls the motor according to the adjusted running rate. The motor power is estimated based on the motor speed, and the running rate is adjusted down if the estimated motor power is too high, thereby preventing overheating of the motor and an inverter, which may be caused in wash or rinse cycles. The apparatus can be implemented without using a temperature sensor, thereby reducing economic burden. Further, the motor does not stop due to an increase in the temperature of the motor, thereby preventing an unnecessary increase in the time required to complete washing.

Abstract: A position controller of a motor in which the position time can be shortened even if an external force is applied. A speed control unit (13) comprises a compensation low-pass filter (133) having a transfer function corresponding to a delay of a speed control system. The speed control unit (13) further comprises an integral control system including a speed integrator (132) for integrating the difference between a speed and a delay speed command to the low-pass filter (133) compensating the delay in the speed control unit. A proportional control system outputting a command proportional to the speed command, and a multiplying means (134) for multiplying the sum of outputs from the integral control system and the proportional control system by a speed proportional gain and outputting the result as a torque command.

Abstract: The invention is directed to controlling an electric motor by means of a frequency converter. The frequency converter can be connected to one of several different mains voltages. According to the present invention, the maximum output power of the frequency converter, is limited when the actual mains voltage is lower than the maximum nominal mains voltage, for which the frequency converter is designed, and during the limitation the frequency converter controls the speed of the motor within a power range up to a limited maximum output power. This gives a genuine multi-voltage unit, which can be connected to a wide range of mains voltages.

Abstract: Motor drives, motor speed controllers, motor speed estimation systems, and methods are presented for controlling motor startup speed and for estimating motor speed during startup, in which a speed estimate controller provides a rotor speed estimate based on a first error term from a torque-based MRAS component for a first range of motor speeds and based on a second error term from a rotor flux-based MRAS component for a second range of speeds.

Abstract: A space-vector pulse-width modulation method for a frequency converter provided with a voltage intermediate circuit, said frequency converter comprising a mains bridge (10) to be connected to an alternating current source (UU, UV, UW), a direct-voltage intermediate circuit and a controlled load bridge (11) for supplying a variable-frequency alternating voltage (US, UR, UT) to a load (12), and in which method the modulator performing the modulation is given a reference. The load bridge modulator is given a reference consisting of the references for the flux linkage changes produced by the voltage vectors, the flux linkage change is calculated on the basis of measured intermediate-circuit voltage, and the currently active voltage vector is kept turned on until the reference value is reached.

Abstract: An electrically powered hand tool is described and which includes a three phase electrical motor having a plurality of poles; an electrical motor drive electrically coupled with the three phase electrical motor; and a source of electrical power which is converted to greater than about 208 volts three-phase and which is electrically coupled with the electrical motor drive.

Abstract: Methods and apparatus for reducing the common mode voltage generated by eliminating zero-voltage vectors in a rectifier/inverter variable frequency drive (VFD) system includes comparing three phase voltages to each other to determine a maximum voltage in one phase, a minimum voltage in another phase and a middle voltage in still another phase, inverting phase voltages for one phase having the maximum voltage and another phase having the minimum voltage, comparing the phase voltages to a carrier wave to determine gating signals for three respective phases of the inverter, and inverting gating signals for the one phase having the maximum voltage and for another phase having the minimum voltage to reduce the common mode voltage in the motor.

Abstract: An electric four-wheel drive vehicle includes: an internal combustion engine; a generator for outputting DC electrical power; an inverter for converting DC electrical power, output from the generator, into AC electrical power; and an AC electric motor, which is driven by the inverter, for driving rear wheels. An electric motor controller controls the inverter, the AC electric motor, and the generator, according to torque instructions from a vehicle. Furthermore, in a case that the output of the AC electric motor becomes negative, and excess electrical energy is generated, the electric motor controller controls the current applied to said AC electric motor such that the loss in said AC electric motor exceeds the negative output of said AC electric motor. This enables the AC electric motor to absorb excess electrical energy in the form of thermal loss.

Abstract: A method and apparatus are implemented in software to control motor speed as a function of available power in a DC source-inverter-AC motor system, i.e. to perform maximum power tracking of motor speed. An inverter or motor drive converts DC power from a DC source, such as a solar panel, to AC power, to power the motor. The inverter or motor drive is controlled by software, implemented either by programmable features built directly into the inverter or drive or by a separate programmable device connected to the inverter or drive, to track motor power as a function of source power. The software-controlled inverter or drive sets motor speed as a function of source power by sensing only a single parameter, the DC source voltage. The software-controlled inverter or drive samples the source voltage at preset intervals, and changes the frequency of the AC output of the inverter or drive to match or track the available power so that the motor operates at or near its optimum for any source voltage.

Abstract: A non-highway vehicle including an engine, a DC power source driven by the engine and providing DC power via a DC bus, a traction motor, a circuit for connection to the DC bus for providing power to the traction motor, and a controller. The circuit includes at least two inverters which share the power supplied to the traction motor. A first inverter connects between the DC bus and the traction motor and a second inverter connects between the DC bus and the traction motor. The second inverter is in parallel connection with the first inverter. The controller coordinates operation of the first and second inverters.