Abstract: Methods, apparatus, and systems are provided for regulating the operation of a drive system within a battery voltage and power range. The apparatus includes a PI regulator producing a signal for regulating a torque output of the drive system based on a DC voltage source limit and/or power limit, a converter normalizing the signal from the PI regulator to produce a new torque limit, and a switch selecting either the new torque limit or an available torque limit of the drive system. The PI regulator includes an integrator having an initial value based on the torque output of the drive system and a copper loss term.

Abstract: A motor driving apparatus including inverter apparatuses, inverter control circuits, and a plurality of inverter control apparatuses for performing variable-speed driving of a single motor, breakers each of which being provided between each inverter apparatus and the motor, the inverter control circuits being connected in parallel to each other. Here, a motor rotation frequency/phase detection circuit of each inverter control circuit is set up on a closer side to the motor than the breakers, then frequency and phase of a terminal voltage at the motor are detected and inputted into failure-time input frequency/phase setting circuits regardless of close/open of each breaker. This feature allows computation by the failure-time input frequency/phase setting circuits to be carried out at all times, thereby making it possible to shorten a computation time needed for computing inverter-apparatus start frequency/phase.

Abstract: A method for controlling an inverter uses sequences of predetermined states where each state uniquely corresponding to a set of control signals provided to the inverter that is coupled to a motor. The method includes repeatedly applying a first center null timing sequence of the states while monitoring a zero crossing condition and then changing the repeated application of the first center null timing sequence of the states into a repeated application of a second center null timing sequence of states when the monitoring detects a zero crossing condition. The repeated application of the first center null timing sequence sequentially provides the inverter with a first predetermined sequence of sets of control signals. The monitoring of a zero crossing condition monitors for a zero crossing condition in an electrical current flowing between the inverter and a terminal of the motor. The second center null timing sequence defines a second predetermined sequence of sets of control signals.

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: 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: Provided is a vector control apparatus for an induction motor which is capable of obtaining stable rotation in a short period of time for adjustment even at the time of low-speed operation by increasing the SN ratio of an output voltage to suppress the arithmetic error in the primary angular frequency arithmetic value based on a magnetic flux command value calculated from a circuit constant and an actual measurement of the induction motor even in the case where the rotation velocity of the induction motor is lower.

Abstract: When multiple motors (40) share a common DC power supply (10) via a bus (20), a system and method is provided for managing the effect of regenerative energy caused by a motor. The regenerative energy may be sensed, e.g., by a power electronics controller (50, 50?). In response, one or more of the other motors currently in operation may be controlled to operate according to a reduced power factor. Thus, the excess energy is consumed without adding any new components or increasing the amount of work performed in the system.

Abstract: In a power inverter system, an inverter unit includes first to third single-phase inverters. In the power inverter system, a reference-frequency calculating unit calculates a reference frequency of each of the first to third single-phase inverters. A reference-voltage-calculating unit calculates a reference voltage of each of the single-phase inverters. In the power inverter system, a voltage-correcting unit adds a correction voltage to the reference voltage calculated by the reference voltage-calculating unit. The correction voltage has a frequency three times as high as the reference frequency.

Abstract: The present invention provides an induction motor controller which includes: a circuit for generating a d-axis current reference signal from a d-axis current command value and a periodically varying periodic signal; a d-axis current controller for controlling a d-axis motor current flowing through an induction motor to be controlled to match the d-axis current reference signal; parameter determining means for calculating and determining a motor parameter of the induction motor based on a deviation of the d-axis motor current from the d-axis current reference signal, and controlling a voltage applied to the induction motor using a compensation voltage calculated from the calculated and determined motor parameter, in which a control parameter for controlling the induction motor is set based on the calculated and determined motor parameter.

Abstract: An insulation-resistance degradation detecting device capable of selecting one of a plurality of motors and detecting its insulation-resistance degradation. A power source unit is connected with a plurality of motor drive amplifiers which drive two motors, individually. The motor is selected by selecting means, and a contactor S1 or S2 is turned on. When a smoothing capacitor C of the power source unit reaches a predetermined voltage after an electromagnetic contactor is turned off, contactors SW1 and SW2 are turned on, whereupon one end of the smoothing capacitor C, contactor SW2, resistors R1 and R2, contactor S1 or S2, coil of the motor, insulation resistor Rx of the motor, grounds G2 and G1, contactor SW1, and the other end of the smoothing capacitor C form a closed circuit. The voltage of the smoothing capacitor C is applied to this closed circuit. A potential difference across the detection resistor R1 is obtained and compared with a reference voltage to detect insulation-resistance degradation.

Abstract: An autonomous controller allows an AC induction motor to operate over a broad range of AC power supply frequencies by reducing the amount of current supplied to the motor at lower frequencies. The controller detects the frequency of the power supply and switches the supply current on and off during each AC cycle to limit the RMS current to a value that is related to the detected frequency. Alternatively, the controller switches capacitive reactance into the power supply circuit which reduces the current supplied to the motor at lower AC frequencies.

Abstract: A general-purpose comparator can be used as a comparison processing module to reduce the costs of a motor drive control apparatus. The apparatus has an electric machine; a magnetic pole position computation processing module; a pattern generation processing module; a switching angle computation processing module which computes a switching angle where switching is done in a next control period based on a pulse pattern; a comparison processing module which compares the magnetic pole position with the computed switching angle to generate a comparison signal; and an on-off output processing module which generates a PWM signal based on the comparison signal indicative of the comparison result. In this case, because the magnetic pole position is compared with the computed switching angle to generate the PWM signal based on the comparison signal, a general-purpose comparator can be used as the comparison processing module.

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

Abstract: A forklift having a cargo apparatus, the responsiveness of which to the operation by a user is improved. The forklift has: a DSP which generates a frequency instruction f* in response to the operation to a cargo apparatus operation lever, a voltage instruction V* from the frequency instruction f* by using the VVVF control, inverter control signals from the voltage instruction v*; an inverter which generates the three-phase electric power in response to the inverter control signal; a hydraulic pump; an induction motor driving a hydraulic pump by using the three-phase electric power; and a cargo apparatus which is driven by the hydraulic pressure supplied from the hydraulic pump.

Abstract: An inverter control device controls the operation of an inverter connected to an electric motor. A switching vector SV is determined as an output switching vector SVo to be supplied to the inverter based on a current deviation of the coil winding of each phase of the electric motor and a switching vector determination table. A keeping time TK is calculated based on a torque and a revolution speed of the electric motor. The counting of a time counting is then initiated. In a high revolution speed (TK>Selection time TS), the control operation for the inverter returns to a start step after the elapse of a certain time period that is set in advance. In a low revolution speed of the electric motor (TK<TS), a zero vector is newly selected as the output switching vector SVo after the elapse of the keeping time TK. The control operation for the inverter then returns to the start step after the elapse of the selection time period TS.

Abstract: A method and system for estimating a parameter of an electric machine, including a controller and a switching device, the controller executes a parameter estimation process, which is responsive to at least one of: a current value and a torque command and the resultant of the parameter estimation process representing an estimated parameter of the electric machine. The parameter estimation includes a method for estimating a temperature of the electric machine comprising: a temperature sensor operatively connected to and transmitting a temperature signal corresponding to a measured temperature to a controller, which executes a temperature estimation process responsive to a temperature signal from a temperature sensor.

Abstract: Synchronous motor controlling apparatus and method controls power applied to minimize or eliminate speed variations of a synchronous motor due to variations in load imposed the motor. The rotational position of a rotor of the synchronous motor based on the input terminal voltages and currents to the synchronous motor, and the power applied to the motor is adjusted accordingly. Higher harmonics of the input voltages and currents may also be used to detect the position of the rotor. In addition, the apparatus and method also accounts for the varying speed command inputs.

Abstract: The driving apparatus according to the invention includes an inverter that drives multiple induction motors connected in parallel, and a secondary current calculating circuit that calculates the components i2W and i2L of a total secondary current value, which is the sum of the secondary currents of all the motors. The apparatus further includes a current deviation quantity calculating circuit that calculates a deviation quantity, for which the total secondary current value deviates from a reference trace. A torque regulating circuit regulates the motor torque based on the calculated deviation quantity. The driving apparatus for driving multiple induction motors according to the invention facilitates quickly detecting the widening caused in the rotating speed differences and preventing the rotating speed differences from widening.

Abstract: A method and apparatus for controlling a permanent magnet synchronous motor by accurately detecting 3-phase motor currents from a DC input current in a full voltage range are provided. In the motor control apparatus for detecting the 3-phase motor currents on the basis of the value of the current detected at a DC side of a PWM inverter, when a difference width between PWM pulse signals of two of three phases of the 3-phase PWM inverter which cannot detect the motor currents is not larger than a predetermined value or when the output voltage of the 3-phase PWM inverter is low, the apparatus automatically reduce the carrier frequency of the PWM inverter.

Abstract: In order to provide an interface circuit, a power converter using the same and an electric vehicle using the same, wherein this interface circuit ensures improved control reliability without employing a photo-coupler, an interface circuit 100A transfers control signals to the power transistor in a large-current circuit 300 from a small-signal circuit 200 for driving a power transistor. The interface circuit 100A has a noise absorber 120 that electrically absorbs a noise voltage produced between the ground of the small-signal circuit 200 and that of the power transistor. The noise absorber 120 transfers to the power transistor the control signals generated by the small-signal circuit 200, without being affected by the noise voltage if produced.

Abstract: A power conversion system for converting a dc voltage to a pulsed ac voltage includes a dc voltage source providing three or more electric potentials, and a switching circuit arranged to connect one of the potentials selectively to an output terminal. A controller produces a pulsed ac output voltage at the output terminal from the potentials of the dc voltage source by controlling an on time for connecting each of the potentials to the output terminal.

Abstract: A frequency converter for outputting a power to drive a motor, having: an inverter unit for inverting a d.c. power to an a.c. power; a control unit for controlling the inverter unit; and a housing for supporting at least the inverter unit and control unit, wherein a rise time change unit is provided in the housing, the rise time change unit changes a rise time of a waveform of a voltage output from the inverter unit.

Abstract: An apparatus and method for controlling a brushless DC motor, which minimizes a torque ripple thereof, and includes a power converting unit to convert alternating current (AC) power to polyphase AC power and to supply the polyphase AC power to the brushless DC motor. A rotator position/speed detecting unit detects status information of a rotator. A terminal voltage detecting unit detects variations of terminal voltages of the polyphase AC power. A control unit detects phase commutation periods of the polyphase AC power using the status information provided from the rotator position/speed detecting unit and the terminal voltage variation information of the polyphase AC power provided from the terminal voltage detecting unit. The control unit controls the power converting unit to supply a compensation voltage used to constantly maintain a mean voltage of a non-commutation phase of the polyphase AC power during the detected phase commutation periods.

Abstract: The present invention is directed to the provision of a servomotor driving apparatus that feeds energy stored in a power storage part connected with a DC link that connects a rectifier circuit with an inverter circuit so that the energy stored in the power storage part can be reduced. A motor driving apparatus (1) includes: a step-up type DC/DC converter circuit (11) for boosting voltage appearing at an output of the power storage part (C1) connected with a DC link; and a DC/AC conversion circuit (12, 14) for converting the boosted DC electric power into AC electric power and feeding it to an electric power source.

Abstract: A method and an apparatus optimize performance of a motor drive system. The method according to one embodiment comprises: selecting a property for a rated operation point; selecting inverter system characteristics and motor characteristics such that a motor drive system including an inverter system having the selected inverter system characteristics operatively connected to a motor having the selected motor characteristics will have a rated operation point exhibiting the property; providing an inverter system having the selected inverter system characteristics; operatively connecting a motor having the selected motor characteristics to the inverter system; and minimizing current of the motor drive system including the motor operatively connected to the inverter system in entire operating range of the motor drive system.

Abstract: To a neutral point of a motor is connected a positive electrode of an auxiliary battery and an auxiliary load. Voltage on a power supply line to the auxiliary load, a neutral point voltage, is detected, and disconnection of the auxiliary battery is determined when an increase of ripples in the neutral point voltage is detected. When a voltmeter cannot be used, control of the neutral point voltage is continued by measuring current of the auxiliary battery and performing control such that the current value becomes 0. A resolver is further provided on the motor for detecting the rotor angle with high accuracy. A control circuit generates, in accordance with an output of the resolver, a voltage control signal for each phase current having the same amplitude as the carrier amplitude during startup, and compares the voltage control signal to carrier to obtain a gate signal having the same frequency as the carrier frequency.

Abstract: A method and apparatus for use with a controller for controlling a machine wherein a torque reference value is provided, the method for identifying an error representative of the difference between the torque reference value and the torque applied to the machine and using the error value to modify machine operation.

Abstract: A reactor having a predetermined small capacity is connected to a rectifier, and a capacitor having a predetermined small capacity is connected between DC bus lines of the inverter, so that a small, light and low-cost inverter controller for driving a motor can be implemented, and even when an inverter DC voltage largely fluctuates and it is difficult to drive the motor, the motor can be kept driving by operating the inverter such that a voltage applied to the motor may stay constant by a motor voltage command corrector which generates a motor voltage command correction value of the motor.

Abstract: The present invention is directed to the termination of the occurrence of wheel slip/skid and prediction and prevention of the onset of wheel slip/skid in a locomotive. In one configuration, a lookup table of adhesion factors is used to predict the occurrence of wheel slip/skid.

Abstract: A power control apparatus includes an inverter giving a rectangular waveform drive signal to an induction motor, an inverter voltage controlling section controlling an output voltage of the inverter, a converter boosting a voltage supplied to the inverter, a converter voltage controlling section controlling an output voltage of the converter, and a control signal generating section that controls the inverter voltage controlling section in a low-rotational speed region and controls the converter voltage controlling section in a high-rotational speed region.

Abstract: A motor drive system without any portion for directly detecting the rotor position, rotation speed and motor phase currents, capable of realizing a high-performance variable speed drive even at high carrier frequencies. When detecting a current from a DC power supply of an inverter for driving a motor, applied voltages and frequencies to the motor are controlled based on sampled values by sampling a current flowing as intermittent pulses in the vicinity of each power conduction time period.

Abstract: While the motor drive amplifier is not operating, electromagnetic switch contacts are held closed for a predetermined period of time, three-phase power is rectified by a rectifier circuit and a smoothing capacitor is charged. Then, the smoothing capacitor is discharged through a discharging resistor and, when a predetermined voltage is reached, a contact is closed, with the result that a closed circuit is formed by the smoothing capacitor, a detection resistor, a motor coil, motor insulation resistance, and ground. A voltage generating across the detection resistor due to leakage current is detected and compared with a reference value. If the detected voltage exceeds the reference value, an insulation degradation signal is delivered.

Abstract: An apparatus for driving a motor of a dishwasher includes an AC power source, a rectification circuit for converting an AC power from the AC power source to a DC power, an inverter circuit for converting the DC power from the rectification circuit to an AC power, a motor driven by the inverter circuit to drive a wash pump and/or a drain pump, a current detector for detecting an output current of the inverter circuit, and a controller for performing a PWM (pulse width modulation) control of the inverter circuit based on an output signal of the current detector to thereby control the motor to rotate at a set rotation speed. A phase difference between an output voltage and the output current of the inverter circuit or a reactive current is controlled to have a predetermined value.

Abstract: A driving circuit of an AC fan motor has an AC to DC converter, a regulated voltage divider, a motor driving unit, two windings each having many coils and a harmonic wave suppression unit. The AC to DC converter converts AC power to high voltage DC power. Since the motor driving unit requires low voltage DC power, the motor driving unit is connected to the AC to DC converter through the regulated voltage divider. The two windings are directly connected to the AC to DC converter to obtain the high voltage DC power. Therefore, when the motor driving unit drives the windings, a large current will pass through the winding to increase rotation ration. Since each winding has many coils, the large current can be held in a suitable range to prevent the winding from being damaged by the large current.

Abstract: An apparatus is provided to control a three-phase AC motor and comprises an inverter and a controller. The inverter powers the motor in response to a three-phase PWM command. The control circuit controls the inverter based on two modulation techniques selectively switched from one the other depending on information indicative of an operation state of the motor. One modulation technique gives the PWM command a first two-phase modulation allowing each phase voltage to be fixed at a predetermined voltage level in turn at intervals of an electrical angle of 2?/3. The other modulation technique gives the PWM command a second two-phase modulation allowing each phase voltage to be fixed at a predetermined voltage in turn at intervals of an electrical angle of ?/3. The switchover can be made between the two-phase and three-phase modulations or can be made with consideration of temperature at switching elements.

Abstract: In switching between asynchronous PWM control and synchronous PWM control, control can be simplified. An apparatus has a first pulse pattern generation processing module which generates a synchronous PWM signal in a first pulse pattern formed of multiple pulses defined in accordance with two or more parameters based on a voltage command value, and a second pulse pattern generation processing module which generates a synchronous PWM signal in a second pulse pattern formed of a single pulse. The first pulse pattern generation processing module modifies the individual parameters in switching pulse patterns between the first pulse pattern and the second pulse pattern. The individual parameters are modified to move the pulse patterns, and thus control can be simplified.

Abstract: A three-phase spindle motor has three terminals each driven with pulse width modulated signals. Rotation of the motor is controlled by iteratively measuring an electrical period of the motor, determining a rotational position of the motor, and synchronizing the sinusoidal pulse width modulation of the spindle motor with the measured electrical period. The electrical period of the motor is measured by detecting zero crossings in the a back electromotive force induced at a first terminal of the motor and determining the time between successive zero crossings. The rotation position of the motor is determined based upon the last measured electrical period and a location of last detected zero crossing. The zero crossings are detected by selecting a time window during which the back electromotive force signal is sensed for zero crossings. The time window is selected as a function of the last measured electrical period and the rotational position of the motor.

Abstract: An AC motor control apparatus that is applicable to commonly used PM motors and capable of detecting the magnetic pole position with simple algorithm. The AC motor control apparatus comprises an inverter for applying arbitrary AC power to an AC motor and a controller for sending a control signal to the inverter. The controller comprises a ripple current generator for supplying a ripple current to the AC motor and a magnetic pole position estimator. The magnetic pole position estimator observes at least two current values of the ripple current for both positive and negative sides of the ripple current to estimate the magnetic pole position of the AC motor.

Abstract: A microprocessor of the motor control apparatus acquires a zero-cross detection signal from a zero-cross detection section and a load current from a current detection section at a prescribed sampling period. The processor obtains a load current instant value every sampling period and a corresponding sine-functional value from a sine-functional value table to calculate a compensation value for the load current instant value. The processor also calculates a load current compensation total value by adding the compensation value by the predetermined number of times of sampling and compares the load current compensation total value with a load current reference value to obtain a difference therebetween. In response to the difference, an instruction value for delay time that determines the output timing of a trigger signal to a switching element is changed so that power consumption of the motor falls within a prescribed range.

Abstract: An apparatus that allows a non-standard brushless motor to be driven with a standard drive amplifier. The motor rotation angle signal from a custom feedback device is converted to a standard format for driving a standard drive amplifier. Operator display and keypad allow interactive format selection and motor parameter display.

Abstract: A method and apparatus control a power converter (20) of an AC motor drive system (10). The method and apparatus: generate a field current regulating signal to control a field current component flowing from the power converter (20) to the AC motor (30), thereby achieving field current regulation; generate a torque current regulating signal to control a torque current component flowing from the power converter (20) to the AC motor (30), thereby achieving torque current regulation, the torque current regulation having lower priority than the field current regulation; and execute a close-loop field weakening control scheme, which generates a field weakening control command as a function of the difference between a torque current regulation voltage demand and voltage available for torque current regulation.

Abstract: A reactor having a predetermined small capacity is connected to a rectifier, and a capacitor having a predetermined small capacity is connected between DC bus lines of the inverter. A PN voltage corrector calculates a ratio of the DC voltage detection value of the inverter obtained by the PN voltage detector to a predetermined DC voltage reference value of the inverter to thereby generate a PN voltage correction factor. A beat amount corrector calculates a fluctuation amount of the motor current from the motor current detection value obtained by the motor current detector and generates a reverse phase component of the motor current fluctuation amount. Thus, a small, light and low-cost inverter controller can be implemented.

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

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

Abstract: A current detection device used for a plurality of rotating electric machines is provided. The rotating electric machines are supplied with a composite current containing a plurality of frequency components from an single inverter and the frequency is set in response to the rotational angular velocity of one rotating electric machine. The current detection device is provided with a current sensor which detects only current components at a single frequency in the composite current. The current sensor detects the currents in a set of supply lines, the supply lines of which being collected and passing through the current sensor so that the current components of the frequency different from the single frequency cancel out to zero in the set of supply lines.

Abstract: An apparatus for driving a brushless motor and method of controlling the motor, which actively changes an output time of a phase commutation signal depending on variation of a load and stably operating the motor in an overloaded state and improving an operational efficiency of a system. The apparatus for driving a brushless motor includes an inverter, a driver, a counter-electromotive voltage detector and a controller. The inverter switches driving voltages applied to multi-phase stator coils. The driver drives the inverter. The counter-electromotive voltage detector detects a counter-electromotive voltage induced from an unexcited stator coil. The controller calculates a time required to detect a counter-electromotive voltage through the counter-electromotive voltage detector after the driving voltage is turned off, determines a phase commutation point of time based on the determined elapsed time, and controls the driver to perform phase commutation at the determined phase commutation time.

Abstract: A motor driving apparatus capable of predicting motor insulation deterioration at low costs. When a motor drive amplifier is not in operation, a relay contact K1 is turned on or closed to form a closed circuit of a motor housing grounded at G2, a motor coil, resistors R1, R2, the relay contact K1, diodes D4, D5, D6, an AC power source, and a ground point G1. A voltage of the AC power source to ground is applied to the closed circuit. When the insulation resistance of the motor is high, a small current flows through the closed circuit, so that potential difference across the resistor R1 is small. If the motor insulation is deteriorated, a leakage current increases. If potential difference across the resistor R1 exceeds a reference voltage determined by a Zener diode, an output signal is output from a comparator, a signal is output from a photocoupler, and the decrease in insulation resistance is indicated on an indicator of a control unit.

Abstract: A control system for an electric motor having a stator and rotor including an inverter for providing power to the electric motor, a controller for controlling the inverter, a low speed control block to estimate the rotor angular position using stator current components operating in the controller, a high speed control block to estimate the rotor angular position using stator current components and stator flux position operating in the controller, a transition switch in the controller to vary operation between the low speed control block and the high speed control block, and where the inverter is controlled by six step operation.

Abstract: A method and apparatus for use with a controller that uses a flux angle position value to control a three phase induction machine, the method for determining an instantaneous flux angle position value in the machine where the machine is characterized by a system specific dominant harmonic frequency number DH that is at least two, the method comprising the steps of injecting a high frequency voltage signal having a high frequency value into the machine thereby generating a high frequency current within the stator windings, obtaining a high frequency feedback signal from the machine, mathematically combining the high frequency value and the dominant harmonic number DH to provide an instantaneous modified angle, using the feedback signal to identify X consecutive calculating instances during each Y consecutive feedback signal cycles where Y is at least two, at each of the X different calculating instances, identifying an instantaneous flux angle position value by mathematically combining a shift angle with the i