Abstract: A gate drive circuit includes a signal generation unit configured to generate a first gate drive signal, a signal isolation unit configured to produce, at an output side thereof in response to the first gate drive signal, a second gate drive signal electrically isolated from the signal generation unit, an output stage device configured to receive the second gate drive signal at an input side thereof and to produce a third gate drive signal at an output side thereof in response to the second gate drive signal, a first path connecting the output side of the signal isolation unit and the input side of the output stage device; and a second path connecting the output side of the signal isolation unit and the output side of the output stage device.

Abstract: A control method of an inverter for outputting polyphase alternate-current electrical power is provided. In the control method, modified PWM pulses of respective phases for controlling semiconductor switching elements of the inverter are generated, based on an output of a counter common to the respective phases. Each of the modified PWM pulses is configured such that a total pulse width, in a period corresponding to one or more cycles of a carrier, is substantially equal to a total pulse width of an assumed PWM pulse which is obtained by comparing, with the carrier, a time average value of an output voltage of the corresponding phase in the period. Further, at least one of a generation timing and a generation frequency of at least one of the modified PWM pulses is changed from the assumed PWM pulse.

Abstract: A control method of an inverter for outputting polyphase alternate-current electrical power is provided. In the control method, modified PWM pulses of respective phases for controlling semiconductor switching elements of the inverter are generated, based on an output of a counter common to the respective phases. Each of the modified PWM pulses is configured such that a total pulse width, in a period corresponding to one or more cycles of a carrier, is substantially equal to a total pulse width of an assumed PWM pulse which is obtained by comparing, with the carrier, a time average value of an output voltage of the corresponding phase in the period. Further, at least one of a generation timing and a generation frequency of at least one of the modified PWM pulses is changed from the assumed PWM pulse.

Abstract: A gate drive circuit includes a signal generation unit configured to generate a first gate drive signal, a signal isolation unit configured to produce, at an output side thereof in response to the first gate drive signal, a second gate drive signal electrically isolated from the signal generation unit, an output stage device configured to receive the second gate drive signal at an input side thereof and to produce a third gate drive signal at an output side thereof in response to the second gate drive signal, a first path connecting the output side of the signal isolation unit and the input side of the output stage device; and a second path connecting the output side of the signal isolation unit and the output side of the output stage device.

Abstract: A control method of an inverter for outputting polyphase alternate-current electrical power is provided. In the control method, modified PWM pulses of respective phases for controlling semiconductor switching elements of the inverter are generated, based on an output of a counter common to the respective phases. Each of the modified PWM pulses is configured such that a total pulse width, in a period corresponding to one or more cycles of a carrier, is substantially equal to a total pulse width of an assumed PWM pulse which is obtained by comparing, with the carrier, a time average value of an output voltage of the corresponding phase in the period. Further, at least one of a generation timing and a generation frequency of at least one of the modified PWM pulses is changed from the assumed PWM pulse.

Abstract: There is provided a motor drive system in which an inverter integrated motor unit 200 and an upper control device 100, which controls an inverter 205 and a motor 207, are formed separated from each other. Various commands for controlling the inverter 205 and motor 207 are wirelessly transmitted to the motor unit 200 from the upper control device 100. The motor unit 200 stores information indicating an operation condition and/or operating history of the motor unit 200 and wirelessly transmits the information to the upper control device 100 in accordance with a command transmitted from the upper control device 100. By transmitting and receiving commands and data using a wireless LAN, or the like, between the upper control device 100 and the motor unit 200, the upper control device 100 can control a plurality of the motor units 200.

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: 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: The present invention provides a variable-speed controlling device for use with an induction motor, which includes a means for compensating for the discrepancy between a secondary magnetic flux instruction value and a secondary magnetic flux actually occurring in an induction motor, realizes a satisfactory control by generating the secondary magnetic flux according to the instruction value, and can generate desired torque and improve a motor efficiency. The variable-speed controlling device according to the present invention, for use with an induction motor, includes a voltage instruction value calculating unit, an integrating unit, a power converting circuit, a current detecting unit, an induced voltage calculating unit, a position discrepancy amount calculating unit, and a compensating unit.

Abstract: A control apparatus for estimating the flux, the current, and the speed of an AC motor using the current and the voltage, and controlling the vector of an AC motor using the estimated speed, a flux command, and a torque current command. The speed is estimated by adding a product of the deviation between the actual value and the estimated value of a magnetization current, the level of a torque current correspondence value, the sign correspondence value of a primary frequency command value, and a gain to an outer product of an estimated current deviation and an estimated flux. Thus, a stable speed estimating operation can be performed to successfully operate the motor in a low speed area in which a voltage frequency applied to the motor is extremely low.

Abstract: A control apparatus for estimating the flux, the current, and the speed of an AC motor using the current and the voltage, and controlling the vector of an AC motor using the estimated speed, a flux command, and a torque current command. The speed is estimated by adding a product of the deviation between the actual value and the estimated value of a magnetization current, the level of a torque current correspondence value, the sign correspondence value of a primary frequency command value, and a gain to an outer product of an estimated current deviation and an estimated flux. Thus, a stable speed estimating operation can be performed to successfully operate the motor in a low speed area in which a voltage frequency applied to the motor is extremely low.

Abstract: A PWM power converter is provided which includes an adder that adds a high-frequency signal from a high-frequency generator to a voltage command signal, and a PWM generator of carrier comparison type or space vector type that generates a PWM signal based on the output of the adder, which PWM signal is used for driving switching devices to provide a desired output voltage.

Abstract: A control apparatus for variably controlling a speed of an induction motor includes a voltage generator, adders, a rotating speed calculating device, a rotating direction detecting device, and a multiplier. The voltage generator is operated for a predetermined period of time at the start or restart of the induction motor to cause self-excited oscillation in a control system including the voltage generator, the induction motor and the PWM inverter. The rotating speed calculating device obtains the rotating speed data, and the rotating direction detecting device detects the rotating direction of the induction motor based on the .alpha.- and .beta.-axis components, on the stationary coordinate, of the primary current of the induction motor. And, the PWM inverter is started based on the obtained rotating speed data and rotating direction.

Abstract: When an induction motor is variable-speed-controlled via an electric power converting circuit, the magnetic flux of the induction motor is modulated by adding an alternating current signal to, for example, a magnetizing current command. For example, the component depending on the slip frequency of the induction motor is extracted by an extracting means from at least one of the amounts of changes of the voltage, the electric current, and the magnetic flux, which are caused by the modulation of the magnetic flux. The amount of the voltage or the electric current supplied to the motor, etc. is controlled based on the extracted component via an adjusting unit and a control means, thereby implementing superior control of the induction motor.

Abstract: A variable-speed control apparatus computes the leakage inductance of an AC motor, correctly compensates the leakage inductance, and controls the variable speed of the AC motor. The variable-speed control apparatus has an AC signal generation circuit for generating an AC signal, and obtains a leakage inductance calculation value of the AC motor based on the AC signal and the measured actual current value. The differential value of the summation of a current command value and the AC signal is multiplied by the leakage inductance calculation value to generate a signal for use in compensating the voltage drop caused by the leakage inductance, and added to a voltage command value to cancel the deviation between the actual current value and the M-axis current command value and to obtain the second voltage command value. The second voltage command value is converted into a 3-phase voltage command value and used in controlling the AC motor, and the voltage drop caused by the leakage inductance can be compensated.

Abstract: To provide a trans-vector controller for an alternating current ("AC") motor that facilitates operating the secondary resistance of the AC motor without experimentally rotating the AC motor.In a preferred embodiment, the variable speed control circuit, including a secondary resistance value generating device, changes the direct current ("DC") exciting current and operates the secondary resistance of an induction motor by superimposing an AC signal with small amplitude outputted from a AC signal generator onto a reference current value immediately before the start of the induction motor in the state of DC excitation.

Abstract: A variable speed controller for an induction motor that estimates the primary angular frequency and the speed without causing any error in the drive region where the induced voltage is low. The primary angular frequency and speed estimating device includes: a changeover signal generator that generates a changeover signal indicative of a first mode of operation when the induced voltage is greater than the changeover threshold, and a second mode of operation when the induced voltage is less than the changeover threshold; a differentiator, filter, etc.

Abstract: A control apparatus for conducting a variable speed control of an AC motor by controlling an M-axis component and a T-axis component of a current flowing through the AC motor.

Abstract: Disclosed are methods and apparatus for quickly measuring a primary resistance value of an AC motor without using high precision detectors and detecting malfunctions such as breaking of wire in the AC motor or in a power converting mechanism, open phase, and three-phase unbalance. A voltage drop attributable to the primary resistance of the AC motor can be estimated by using an estimated resistance value R.sub.1.sup.#, which is estimated in turn by an integral or proportional-plus-integral operation on the deviation between a detected magnetizing current value I.sub.M and a reference magnetizing current value I.sub.M *, in place of an actual primary resistance value R.sub.1. The time for the estimated resistance value R.sub.1.sup.# to reach the true primary resistance value is reduced with a varying reference magnetizing current value I.sub.M **. Variations of the estimated primary resistance values R.sub.1.sup.# s between the phases are corrected with a mean estimated primary resistance value R.sub.1M.sup.

Abstract: An apparatus for driving an AC motor at variable speeds facilitates arbitrary setting or adjustment of equivalent primary resistance of an AC motor. In one embodiment of the present invention, a reference AC voltage generator outputs reference AC voltage values for each phase of the AC motor, and signals derived from the reference voltage values are in turn used by a power converter to supply the AC motor with variable voltage and frequency. In this embodiment, two or more phase currents are fed back to, and subtracted from, the reference voltage values via a regulator. In another embodiment, an angular-frequency/biaxial-reference-voltage value generator generates a reference primary angular frequency value and biaxial reference voltage values of the AC motor in a rotating orthogonal coordinate system. In this embodiment, two or more of the AC motor's phase currents are fed back to, and subtracted from, the biaxial reference voltage values via a vector transformer and a regulator.