Abstract: In an electronically commutated motor, both the driving current (i2) and the braking current (i2′) are monitored. When excessive driving current occurs, a pulse duty factor which regulates the current is reduced. When excessive braking current occurs, this pulse duty factor is increased. For this purpose, an analog circuit with two current limiting members is disclosed, as well as a circuit in which these functions are implemented by software in a microcontroller, so that current measurement can be dispensed with. Finally, a combination of these features is disclosed, in which hardware current limitation and software current limitation work together.

Abstract: A power electrical system is disclosed for a microturbine power generator. The invention permits the microturbine to be started using an external DC power source. The DC voltage is converted to a variable DC voltage by means of a bi-directional buck-boost circuit, DC bus and a DC-to-AC converter. The DC-to-AC converter produces at its output a fixed voltage pattern whose frequency is gradually increased in concert with the DC voltage, to accelerate the microturbine from standstill to startup speed. Once the microturbine is started, the excitation is discontinued, and the DC bus and DC-to-AC are used to produce output AC power at a voltage level and frequency to match an electrical load.

Abstract: A control apparatus for an electrical power steering apparatus whereby a high output, small motor can be achieved, variation in the relative magnetization and coil positions and position detection precision requirements can be alleviated, steering feeling is improved, and apparatus cost is reduced. In a control apparatus for an electrical power steering apparatus for controlling a motor applying steering assistance force to a steering mechanism based on a current control value calculated from the current of a dc motor or brushless motor and a steering assistance control value calculated based on steering torque occurring at the steering shaft, torque ripple of the motor is suppressed to 10% or less.

Abstract: A motor control system 16 for use within an electric vehicle 10 having an induction motor 12. Control system 16 utilizes a torque control module 18, a vector control module 20 and a space vector PWM module 22 to efficiently and accurately control the torque provided by motor 12.

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: An induction motor control system (10) for electric vehicles having a DC power supply (14), an inverter (16), an induction motor (12), a motor controller (26) and a vehicle-level controller (32). The method and system of the present invention optimizes the torque output for the induction motor and utilizes minimum power. The method and system of the present invention calculates the flux current such that the slip frequency is maintained at a nominal level, thereby producing peak torque.

Abstract: The present invention concerns a method for symmetrizing asymmetric faults occurring within a pull chain comprising a synchronous or asynchronous motor controlled by a two-level or multi-level inverter consisting of static switches using semiconductors such as IGBT or bipolar transistors. The invention comprises detecting whether the fault connects or may connect a motor phase with the top point or the bottom point of the inverter power supply, and short-circuiting only the half of the inverter affected by the fault on the basis of the detection.

Abstract: An electric drive apparatus and method for controlling AC motors wherein the motor output is a function of the AC input power to the electric drive. Means are provided for detecting the voltage being supplied by the source of AC power to a drive circuit, and for controlling the output to the multi-phase AC load based on the detected power level. A controller monitors the motor voltage, current, and speed or frequency while also receiving a command for torque or torque-producing current. The method provides for the operation of the drive circuit in the event of either a partial or complete loss of AC input power. During such an occurrence, the controller will cause the circuit to generate sufficient negative torque to cause a power flow from the motor to the drive circuit to substantially equal the inherent losses in the drive and motor to avoid loss of energy from the DC filter of the drive circuit. Motor torque and speed can be quickly restored when the input power is re-established.

Abstract: A compressor driving apparatus comprises a module including a power supply, an inverter for driving a compressor, an inverter driver for driving the inverter, a CPU for generating a signal to be used for driving the inverter and having a function for communicating with outside, a storage circuit for storing data which is alterable from an external device, and a relay driver for driving an external relay. The inverter and other circuit components are disposed within the module such that they are thermally separate such that an inverter driving signal from the CPU is transferred accurately to the inverter and that a power supply having an output voltage with low distortion is realized, thereby improving the operating efficiency of the compressor. Because the storage circuit and the power supply circuit are built-in, standardization of the compressor driving apparatus is easily realized.

Abstract: An AC to DC to AC converter has an input to receive input AC, a rectifier to rectify the input AC to DC, and an inverter to invert the DC to output AC. A load sensor senses load on the AC to DC to AC converter. A fan directs a cooling fluid to the AC to DC to AC converter. A fan control has an input coupled to the AC to DC to AC converter so as to receive DC therefrom, an input coupled to the load sensor, and an output coupled to the fan. The fan control controls the fan at a variable speed in response to load on the AC to DC to AC converter so as to vary the cooling fluid delivered by the fan to the AC to DC to AC converter.

Abstract: This invention relates to a brushless motor driving system for driving an outdoor fan of an air conditioner. The driving system comprises a Hall probe for detecting a position of a rotor of a brushless motor, an inverter circuit consisting of a plurality of switching elements connected in bridge-connection, the inverter circuit supplying ON-OFF electric current to stator coils of the brushless motor, and a control means for switching the switching elements of the inverter circuit based on the output signal of the Hall probe. Before starting the motor, the control means controlls the switching elements to supply DC PWM-controlled current to the stator coils of the motor in synchronization with the output signal of the Hall probe, so that the rotor is braked, stopped and set to home position.

Abstract: A noise attenuation circuit is disclosed for use in a motor drive system. The motor drive system includes a pulse width modulated inverter providing three phase power output on three phase conductors for driving a motor. The noise attenuation circuit includes a common mode transformer including a common mode choke having a core, with first, second and third choke windings on the core, each connected in series with one of the three phase conductors, and a fourth winding on the core. A three phase iron core transformer creates a neutral point representing common mode voltage. The iron core transformer has three primary windings connected in a wye configuration. A capacitor circuit is connected between the iron core transformer and the three phase conductors to prevent saturation of the iron core transformer during pulsed DC operating conditions. The fourth winding is connected between the neutral point and the DC bus and develops a common mode voltage that is equal and opposite to that existing in the system.

Abstract: An actuator (12) has a movable member (20), and has a coil (26) which can be controlled to urge the member to move. In a particular mode of operation, a driver circuit (70) is periodically uncoupled from the coil so that the current through the coil goes to zero, after which the back-emf voltage of the coil is applied to a capacitor (94). Then, the driver circuit is recoupled to the coil, and the voltage held by the capacitor is used to effect feedback control of the driver circuit for the coil.

Abstract: A method for controlling the starting, stopping and operation of an AC motor is provided. Each winding of the AC motor is interconnected to an AC source by a thyristor switch and a bypass contactor for providing voltage and current to the AC motor. The method includes a steps of sequently firing a pair of tyristor switches to bring the AC motor to full operating speed. Once at operating speed, the bypass contactors are closed. Upon detection of a voltage drop across a thyristor switch, the thyristor switch is fired immediately to transfer motor current from the bypass contactor to the thyristor switch in order to maintain voltage and current to the AC motor.

Abstract: A method for detecting a change in motor load and/or motor speed is provided. The method includes the step of measuring the number of transitions (i.e., state changes) of a phase control signal in a motor phase of the motor. The method also includes the step of comparing the number of transitions to a predetermined number that is indicative of a predetermined motor load and/or motor speed. The predetermined number may comprise the number of transitions in a prior phase control signal of the motor. A method for controlling a motor responsive to a change in motor load and/or motor speed is also provided. The method includes the above-described steps for detecting a change in motor load and/or motor speed and further includes the step of selecting one of a plurality of operating modes for the motor responsive to a comparison value obtained by comparing the measured transition number with the predetermined transition number.

Abstract: Converter-powered electric motors are often braked by electrical means. For this purpose the electronic converter that powers the motor is so controlled that the motor, when in generational operation, sends energy by way of the converter into an electrical braking resistor additionally connected to the converter, and this energy is there converted to heat. In order to avoid overloading the electrical braking resistor, an additional electronic or thermo-mechanical protective device is customarily provided. To simplify the arrangement, it is proposed in the present invention to provide as an electric braking resistor one made of a resistive material with a conductance that decreases progressively as the temperature rises through a certain range below the maximal acceptable operating temperature of the braking resistor. As a result, the power that can be accepted by the electrical braking resistor is made self-limiting, so that the braking resistor is protected against overheating.

Abstract: Driving of a three-phase motor includes controlling the slip of the motor by way of a fuzzy logic algorithm. The simplicity and precision of the fuzzy control of the slip permits dynamically optimizing the efficiency of a three-phase motor under any operating condition, and thereby minimizing power consumption. The control is carried out by knowing: the effective speed of the motor that represents the feedback value, and that may be provided by a common encoder (typically a dynamo or an optic device) keyed on the motor's spindled; the stator frequency imposed on the motor; the required speed; and, of course, the characteristic curve (frequency-torque) of the motor.

Abstract: There is provided a controlling apparatus for an air conditioner, which comprises: an inverter circuit for feeding as an output a pseudo-sine wave from a switching signal obtained by comparison between a modulated wave and a carrier wave; a refrigeration cycle device which has a compressor driven by the pseudo-sine wave from the inverter circuit so that the modulated wave is adjusted according to a load of an air conditioner; and a correction device for correcting an amplitude of the modulated wave into a smaller one at a predetermined time when a rated voltage of the power source from the inverter circuit is larger than a rated voltage by a first predetermined value, and correcting the modulated wave into a larger one at a predetermined time when a rated voltage of the power source from the inverter circuit is smaller than the rated voltage by a second predetermined value.

Abstract: A motor current sensing circuit using a single sensing resistor in the motor current path to sense the current from the voltage source. The circuit includes an amplifier and a unity-gain inverter that translate the current across the sensing resistor into a voltage analog of the current in the motor. At any instant in time, the magnitude of the voltage across the sensing resistor is proportional to the magnitude of the motor current. During the forward portion of the duty cycle, a high-speed switch connects the sensor output to the amplified sensed bus current analog. During the reverse portion, the sensor output is connected to the inverted bus current analog. The average value of the sensor output is the voltage analog of the average value of the motor current.

Abstract: A method and a device for controlling a sensorless, field-oriented asynchronous machine, wherein a manipulated variable space vector and a stator frequency are calculated, by means of a two-component current control system, from which control signals are generated using a space vector modulation process. A PI controller of an EMF control system for the d-component of a calculated EMR space vector of the field-oriented control system is deactivated and its output signal set to zero at a stator frequency, determined as a function of a calculated d-component of a calculated EMF space vector and a calculated stator frequency, that is less than or equal to a first limit frequency. Thus, the method may be used for speed control of a sensorless, field-oriented asynchronous machine down to a full stop.

Abstract: In a motor control system and method controlled by a d-axis current command value i.sub.ds and a q-axis current command value i.sub.qs, a d-axis voltage command value V.sub.d * and a q-axis voltage command value v.sub.q * are computed on the basis of d-axis current deviation .DELTA.i.sub.d of d-axis current value i.sub.d from the d-axis current command value i.sub.ds and q-axis current deviation .DELTA.i.sub.q of q-axis current value i.sub.q from the q-axis current command value i.sub.qs and on the basis of q-axis inductance value L.sub.q and d-axis inductance value L.sub.d wherein the inductance values L.sub.q and L.sub.d are tuned or adjusted so that the d-axis current deviation .DELTA.i.sub.d and q-axis current deviation .DELTA.i.sub.q approach zero.

Abstract: A speed controller for a three phase induction motor using sliding mode control to generate estimates of stator current and rotor flux to control motor speed. The controller receives only the actual operating speed and the desired operating speed as input signals. The controller establishes linked non-linear hyperplaces containing the operating points of each phase and coerces the operating points to move along the line of intersection. A change in operating conditions causes a change in the power supplied to the phase terminals.

Abstract: A frequency converter for an asynchronous motor including a voltage converter (O) equipped with switches (Sa, Sb, Sc) controlled by a control circuit (CC) and powered by a DC bus (B) on which a shunt (Sh) is installed to measure a DC current passing through the bus, wherein, when at least one of two components of an output voltage vector Vs is less than a predetermined value TMIN, the frequency converter includes a device which calculates firstly a vector Vs' each of two components thereof being at least equal to the predetermined value TMIN, and secondly a vector Vs" such that vectorial average of Vs' and Vs" is equal to the output vector Vs.

Abstract: A circuit comprises a two-way switch and an inductor and is disposed between an ac power source and a rectifier so that the circuit provides a voltage higher than the source voltage. The unit provides a high voltage dc power to charge a battery of an electric vehicle. If the inductor is accurately grounded, the circuit stops the flow of dc current thus preventing electric corrosion in the vehicle body.

Abstract: The invention relates to a method of ensuring the stability of a synchronous machine in controlling the synchronous machine on the basis of direct control of flux and torque, in which the torque generated by the synchronous machine is increased/decreased by increasing/decreasing the instantaneous angular velocity of the stator flux. In accordance with the invention, the method comprises the steps of determining the direction of the stator flux vector (.psi.s) in rotor coordinates (dq), and forcing the stator flux vector (.psi.s) to remain in quadrants I and IV (Q1, Q4) of the rotor coordinates by rotating the stator flux in the rotor coordinates to a necessary degree.

Abstract: An apparatus for controlling a driving signal for a motor for converting an AC input signal to an instantaneous DC signal, thereby achieving a desirable control, which is capable of preventing a phase delay and corresponding a sudden signal change by converting the AC input signal to the instantaneous DC signal and controlling to correct a difference value between the DC signal and a reference signal.

Abstract: The invention relates to a method and an apparatus for braking a synchronous motor (2) magnetized with permanent magnets. According to the invention, there is connected to the input connectors (38,40,42) of the synchronous motor a non-linear braking resistor (60) by means of which the stator windings of the synchronous motor (2) are closed.

Abstract: A method for stepwise voltage control using thyristors for supplying an induction motor at a fixed frequency and a variable voltage. A time sequence of electromotive force amplitudes corresponding to a predetermined law for torque variation during transient operating conditions is stored. Voltages applied to the motor and the current flow are determined to approximate the electromotive force generated by the motor. Static switch conduction intervals are used to adapt the electromotive force to the stored amplitude during the transient operating conditions.

Abstract: A load-commutated synchronous motor drive has a line-commutated network-side converter (3), a current-source dc intermediate link (PL, NL, 5) and a load-commutated machine-side converter (2) for connection to a synchronous machine (1). The motor drive comprises control members adapted, to ensure the commutation, in connection with commutation of the machine-side converter (2), to switch the network-side converter (3) for operation with a lower pulse number than the natural pulse number of the network-side converter.

Abstract: An electric current compensation circuit for use with a multiple-phase burshless motor to reduce ripples in the output torque is disclosed. It contains a plurality of electric current compensation loops each for a respective phase winding and each of the electric compensation loops contains: (a) a first input for receiving a line current from the driver; (b) a second input for receiving the compensation current from the motor sensor; (c) a forward rectifying circuit for forwardly rectifying the line current and the compensation current; (d) a reverse rectifying circuit for reversely rectifying the line current and the compensation current; and (e) a summation circuit for summing the forwardly rectified compensation current and the reversely rectified compensation current and outputting a synthetic current to a phase winding of the motor.

Abstract: A commutation control strategy for eliminating torque ripple and noise from a brushless motor which has a plurality of motor phases connected in a bridge, each phase having a top switching device provided between a phase winding and a positive voltage supply and a bottom switching device provided between the phase winding and a less positive voltage supply in which following commutations of the motor, when the current flowing in a first phase is decaying towards zero and the current in a second phase is rising from zero, the switching devices are operative between a state in which the current flowing in the first phase is caused to decay at a first rate, and another state in which the current flowing in the first phase is caused to decay at a second rate which is lower than the first rate so that the rate of decay of the current in the first phase substantially matches the rate of rise of the current in the second phase.

Abstract: The invention concerns an improved system for windshield wipers in vehicles. An induction motor is used, in which speed is accurately controlled by controlling frequency of power supplied to the motor. The induction motor may be of the consequent-pole type, which ordinarily does not produce sufficient torque. Addition of (a) auxiliary tooth slotting and (b) skew has raised the torque produced to acceptable levels.The invention includes a control system, which senses excess load on the motor, which occurs as the windshield dries, and reduces motor speed, subject to a minimum, in response.

Abstract: A method and apparatus for controlling a regenerative drive having line and load converters connected by a DC link, the load converter for connection to an AC machine, and the line converter for connection to an AC source/sink by means of line reactors, the drive for causing real power to flow in the line reactors to control the DC link voltage at a selected DC voltage and for determining when a commanded line converter voltage exceeds a selected maximum line converter voltage for also causing reactive power to flow in the line reactors to reduce the line converter voltage required to control the real power flow.

Abstract: A disk drive including firmware for overcoming stiction and breaking free the heads of a disk drive which may adhere to the disk surface when the disk is at rest. Upon start-up of the disk drive, if stiction at the head/disk interface occurs, the voltage to the spindle motor and/or actuator motor may be rapidly fluctuated so as to cause a pulsing of the spindle motor and/or actuator motor. Pulsing both the spindle motor and actuator motor creates forces in a plurality of radial directions to allow the head(s) to break free from the disk(s) in the direction of least resistance. Moreover, as the resonant frequency of the spindle motor varies depending on the number of heads that are stuck, the firmware pulses over a range of frequencies including the various resonant frequencies of the spindle motor corresponding to various numbers of heads stuck.

Abstract: An electronic control unit for controlling an inverter mounted between a main battery and a motor in an electric vehicle includes a feed-back control device which ensures that an actual electric power calculated from an electric current and a voltage inputted to the inverter is equalized to a target electric power calculated from the motor revolution-number, an accelerator opening degree and a shift position. If a circuit between the main battery and the motor is opened during regenerative operation, so that the charging of the main battery with a regenerative electric power cannot be performed and as a result, the voltage is increased to exceed a predetermined value, a regeneration prohibiting device prohibits the regenerative operation of the motor to prevent damage to the inverter due to a counter-electromotive voltage of the motor.

Abstract: In a motor drive circuit, the collector-emitter paths of two npn-type transistors are connected in series between a power line and ground, and the junction between the two transistors is connected to a motor coil. A control circuit feeds a control current to the base of the transistor connected to the power line so that this transistor supplies a drive current to the motor coil. A current mirror circuit is provided which is constituted of two pnp-type transistors whose emitters are connected to the power line, and the base and collector of the input-side transistor is connected to the control circuit through a diode. The base of another pnp-type transistor is connected to the cathode of the diode, and the emitter of this transistor is connected to the collector of the output-side transistor of the current mirror circuit and to the base of the transistor connected to the power line.

Abstract: A variable frequency motor drive incorporating a circuit interrupter includes a rectifying circuit for converting incoming AC power to DC power and an inverting circuit for converting the DC power to controlled AC power in response to control signals. A control circuit implements a preset control routine to control operation of the inverting circuit to drive a motor in accordance with desired operating parameters. A circuit interrupter is coupled between the source of AC power and the rectifying circuit and includes an actuator for interrupting power to the drive in response to interrupt command signals from the motor control circuit. The motor drive includes a switching circuit and a capacitive circuit for powering the circuit interrupter. The drive control circuitry monitors operation of the drive and the motor and when conditions require removal of power to the drive, the control circuitry commands the switching circuit to close, energizing the circuit interrupter and thereby removing power to the drive.

Abstract: Disclosed is a method of controlling an internal combustion engine driven electric vehicle in power operation of the vehicle, in which control is made so that a voltage of a DC intermediate circuit is maintained to a first constant DC voltage in a first speed range of from a zero vehicle speed to a first vehicle speed, the voltage of the DC intermediate circuit is changed in proportion to the vehicle speed in the second speed range of from the first vehicle speed to a second vehicle speed, and the voltage of the DC intermediate circuit is made to be a second constant DC voltage in the third speed range not lower than the second vehicle speed, and control is further made so that an AC output of the second power converter is made to have a variable voltage and a variable frequency in the first and second speed ranges, while the AC output of the second power converter is made to have a constant voltage and a variable frequency in the third speed range.

Abstract: A control system (100) for a five-phase brushless DC motor (102) including a stator having five windings and a rotor (116) mounted for rotation relative to the windings (114). The windings (114) are adapted to be electronically commutated in response to the rotary position of the rotor (116). The control system (100) includes a sensing circuit (106) to sense the rotary position of the rotor (116) using an optical or magnetic sensor or the back electromotive force voltages in the windings (114). Electronic switches (112) control the flow of current through the windings (114) in response to control signals generated by a control circuit (110) in response to the rotary position of the rotor (116). The control circuit (110) includes start-up logic to start the motor (102).

Abstract: A method and an apparatus for direct torque control are specified for a three-phase machine fed via a harmonic filter, which method manages as far as possible without any major adaptation to already known DTC methods and DTC apparatuses. In addition, the oscillations caused by the filter are intended to be damped effectively. This is achieved in that a current flowing through the filter and/or a filter output voltage are/is measured, and the reference flux value and the reference torque value are corrected on the basis of the measured voltage and/or of the measured current. The correction comprises a transformation of the filter output voltage into a first component at right angles to a stator flux and into a second component parallel to the stator flux, as well as a reduction in the reference torque and flux values in proportion to the oscillating part of the filter output voltage.

Abstract: A motor control system for controlling power supplied to an electric motor rotating a rotor employed in a centrifuge is provided. The motor control system includes first, second, and third converters and first and second smoothing capacitors. In a motor power mode, the first converter operates to transfer the charged energy in the first smoothing capacitor to the second smoothing capacitor for providing power to the motor through the third converter, while the second converter transfers, in a motor braking mode, the charged energy in the second smoothing capacitor to the first smoothing capacitor to return the power regenerated by the motor during a braking operation to the AC power supply through the first converter. The second converter performs a function of providing an initial energizing energy to the motor for a given period of time at the start of the braking operation for stability of a power-regenerating operation of the motor.

Abstract: The invention relates to an apparatus for regulating the speed of an a.c. elevator motor (10) by means of a frequency converter (8) consisting of a rectifier bridge (12) and an inverter bridge (14) with an intermediate circuit between them. The frequency of the frequency converter is adjusted until it corresponds to a frequency reference (f.sub.ref) corresponding to the speed reference (v.sub.ref,v.sub.ref ') of the motor. The velocity of the motor (v.sub.real) is measured to form a speed feedback signal. According to the invention, the apparatus has elements (24,26) for correcting the speed reference (v.sub.ref) on the basis of the change occurring in the voltage (U.sub.c) of the intermediate circuit.

Abstract: A method and apparatus for the control of an AC-machine is set forth with a special winding for the combined generation of a torque and of a transverse force in the machine. In this arrangement, the magnitude and direction of a transverse force acting on the rotor of an AC-machine is controlled via the current of a control winding of the machine. For this purpose, the magnitude and direction of a flux of the machine generated by a drive winding and also the torque-forming component of the drive current is detected. From these parameters, the desired value of the control current vector can be precisely calculated via a decoupling equation in a coordinate system which is rotating with the machine flux. Through vector rotation, through the flux angle and a constant angle, which takes into account of the position of the winding axes of the drive and control windings, the desired value of the control current vector can be transformed into the stator coordinate system of the control winding.

Abstract: A frequency converter device comprises a first converter 5 in a pulse-width modulation system for converting an AC voltage into a DC voltage; a second converter 2 in a pulse-width modulation system for supplying an AC voltage with a variable voltage and a variable frequency to a motor; a capacitor 15 connected between an output side of said first converter 5 and an input side of said second converter 15; a current suppressing circuit connected to the input side of said first converter 5 and consisting of a resistor 31 and a relay 32; a detection circuit 19 for detecting the presence or absence of the power supply inputted to said first converter 5; a circuit 16 for measuring the voltage across said capacitor 15; a drive control circuit 30a for stopping the conversion of said first converter 5 when power failure of an input power supply occurs and when the voltage across the capacitor is not smaller than a prescribed value, continuing the drive state of the relay 32 and said second converter 2, thereby continu

Abstract: A driver for an induction motor includes a voltage limiter which limits an upper limit value of an output voltage from an invertor circuit in accordance with an output frequency command, a lowest frequency limiter which limits a lower limit of an output frequency from the invertor circuit, a forward rotation limiter which outputs a first power supply interruption signal when the output frequency from the invertor circuit reaches the upper limit, a reverse rotation limiter which outputs a second power supply interruption signal when a reverse rotational speed of the motor reaches a reverse rotation limit level, and a low-speed overload detector which outputs a third power supply interruption signal when a state in which the second power supply interruption signal is not output continues in a low speed abnormality state.

Abstract: A control apparatus for an electric vehicle has an inverter for feeding currents to a three-phase AC motor corresponding to applied PWM signals, three current sensors, each of the sensors detecting a current of a respective phase in the three-phase AC motor, a revolution speed detector for detecting the speed of the three-phase AC motor, a motor control unit for controlling the three-phase AC motor which includes a current demand generating unit, a current control unit for performing feedback control based on the current demands and currents detected by the current sensors, and a PWM signal generating unit.

Abstract: A control apparatus for controlling a motor of an air conditioner includes a converter, having switching for improving an input power factor, for converting an AC power to a DC power and an inverter for converting the DC power supplied from the converter to the AC power and supplying to a compressor. The output DC voltage of the converter is detected by a DC voltage detecting circuit. An input alternating current is detected by a current detecting circuit. A microcomputer for controlling the inverter calculates a current command from data stored on the basis of the detected voltage. The detected current is compared with the current command, an ON percentage of a PWM signal to control the switching is obtained, and the PWM signal is generated.

Abstract: This invention provides cost-effective suppressing conducted radio-noise emissions from industrial inverter-motor drives whose EMI performance is able to meet the CISPR or FCC limits on conducted emissions. The invention includes some small size L,C filtering elements built inside the inverter, e.g., two grounding capacitance connected from both side of DC link to grounding heat sink of devices, a line capacitance across a DC link, three line capacitances across phase leads in AC input side of the diode rectifier, a zero sequence inductance both in each phase input and in each phase output lead of the inverter. Optionally, an extra secondary winding of the zero sequence inductor is connected to main circuit of inverter via a L, R, C network.

Abstract: A power supply for vibrating compressors having an inverter for converting direct current (d-c) into alternating current (a-c). The power supply includes a d-c power source section for applying d-c voltage to the inverter, a current detecting apparatures for detecting a current flowing in the vibrating compressor, a control section having a frequency following circuit for generating a frequency following the resonance frequency of the vibrating compressor on the basis of a current detected by the current detecting apparatures, and an inverter control circuit for controlling the inverter with the frequency generated by the frequency following circuit. The vibrating compressor is driven by an a-c voltage of the frequency agreeing with the resonance frequency of the vibrating compressor.

Abstract: An asynchronous motor is supplied with power from an AC line voltage via a variable speed drive including a rectifier bridge connected to the AC line voltage, a DC voltage intermediate circuit including a capacitor and an inverter including switches and connected to the phase windings of the motor. A system for controlling the power supply to the motor includes a device for controlled resumption of motor speed after supply of power to the motor is interrupted.