Abstract: The invention relates to a method of starting an asynchronous machine irrespective of whether the rotor of the machine is rotating or not when the machine is supplied by an inverter provided with a separate moment and flux or moment and magnetizing current control, which is faster than the time constants of the asynchronous machine. According to the invention, zero moment is set as a target for the control, a voltage is supplied to the stator of the machine by the inverter, a stator current vector and a stator flux generated by the voltage is determined, an estimate of that vector or some other quantity comparable to the stator flux is determined, a moment caused by the stator flux vector and the stator current vector is determined and information of the moment is supplied to the control, which tries to zero the caused moment by making the stator flux and a rotor flux generated thereby cophasal, thus synchronizing the supply frequency of the inverter with a possible rotation of the machine rotor.

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.

Abstract: A method and apparatus to be used with a motor controller for determining RMS line current during a start-up period or a stalled period using electrical values known to the controller. Various equations relate RMS line current to monitored thyristor and source voltages as well as the duration of non-conducting periods in line voltages to determine the RMS line current.

Abstract: In order to reduce distortion of a real-current wave form and to suppress substantial transient fluctuation of the current and torque during changeover from a regeneration running condition to the power running condition of a three-phase induction motor, changeover from the three-phase-modulation control to the two-phase-modulation control is carried at the same time the power running condition of the motor is changed to the regeneration running condition according to the motor-state-quantum such as a detected slip ratio, detected torque, detected current or the like. Thus, distortion of the motor-current wave form is reduced and significant fluctuation of the motor-current and torque during the changeover is reduced.

Abstract: A controller for use with AC induction motors utilizes a microcontroller in conjunction with a triac to control the duty cycle of the AC power applied to the motor. A voltage sensing circuit provides signals to the microcontroller. The microcontroller is also coupled to the gate of a triac. The microcontroller automatically selects the appropriate parameters for most efficient motor operation based upon the motor power factor as determined by the time at which the voltage across the motor crosses zero and the voltage at the triac gate crosses zero.

Abstract: A method and apparatus to be used with a motor controller for determining if phase currents in a three phase AC motor are balanced. The phase angles between current zero crossing times for consecutive phase currents are compared to determine current balance and thyristor switches are employed to adjust phase angles and rebalance unbalanced currents.

Abstract: A shredder motor circuit with power factor correction is provided. A permanent split capacitor motor under full load will run at peak efficiency with a high power factor. However, at no-load or at partial load the power factor will drop significantly, resulting in wasted energy and a possible overheating of the motor. This condition is inventively corrected by the present invention by lowering the voltage to the motor when the motor is partially loaded. The purpose of this shredder motor circuit with power factor correction is to vary the voltage to the motor instantaneously as the load changes due to increased amounts of paper placed in the shredder and thereby supplying the right amount of power required to result in higher efficiency and a cooler operating motor.

Abstract: In an apparatus for regulating the power consumption of a vacuum cleaner, it is proposed to detect the pulsating alternating current present at the driving electric motor and delivered by a phase-angle circuit by means of a parallel voltage sensor, rectify it, smooth it, digitize it, and, on the basis of data stored in tabular form from a memory arranged in a microprocessor, convert it into a true effective value of the motor voltage; and subsequently to compare it with various associated respective manually defined power data and to activate the phase-angle circuit so that irrespective of fluctuations or different power system alternating voltages or frequencies, motor output is regulated to constant values corresponding to the manual setting.

Abstract: A variable speed control for induction motors with a primary angular frequency operating circuit has a multiplier that multiplies the output of a first regulator by a variable responsive to magnetic flux intensity. This first regulator holds the M axis induced voltage at zero. The primary angular frequency operating circuit corrects the primary angular frequency command value based on the output of the multiplier. An adder adds the output of a second regulator circuit and the output of the primary angular frequency operating circuit. The second regulator regulates (by proportional or proportional-integral control) the deviation between the command value of the torque current, or the torque and an actual value, to zero. In another embodiment, the magnetic flux operating circuit calculates a first value and a second value.

Abstract: The invention provides a control apparatus for an induction motor to maintain torque following controllability even with use of inexpensive speed detection units having detection delay. In a control unit, a phase correction arithmetic circuit uses a motor speed detection value detected by a speed sensor and a low-pass filter and a detection delay time of a control system to compute a correction phase. An adder adds the correction phase to a magnetic flux phase obtained by a vector control computation. The addition corrects a magnetic flux phase deviation due to detection delay of the correction phase of a primary current command, and compensates for the detection delay so as to maintain the torque following controllability of an inductor motor.

Abstract: A power converter having a DC power source and neutral point clamped inverters connected in common to the DC power source, to convert DC power from the DC power source into AC power and supply the AC power from the inverters to a load. The power converter includes a first voltage reference generating unit for generating a first voltage reference, and a phase difference determining unit for determining a phase difference between the inverters based on a number of the inverters and a number of phases per the inverter. The power converter further includes a second voltage reference generating unit for generating a second voltage reference based on the first voltage reference from the first voltage reference generating unit and the phase difference from the phase difference determining unit, and a comparing unit for comparing the voltage references with carrier signals repectively and for generating gate signals based on the comparison result to the inverters.

Abstract: Methods and apparatus are provided wherein air gap fundamental flux magnitude and relative position are determined from stator voltage third harmonic components and stator current in operating alternating current machines having a stator, a rotor and an air gap therebetween. Such determinations have various uses, such as for efficiency control.

Abstract: In a field-oriented control method and apparatus for an induction motor, a desired quadrature-axis current i.sub.q * and a desired direct-axis current i.sub.d * are chosen. The desired quadrature-axis current i.sub.q * and desired direct-axis current i.sub.d * are related such that peak torque is produced by the motor per ampere of electric current flowing in the motor. The peak-torque-per-ampere condition implies that the motor is operating at high efficiency.Also, in a field oriented control method and apparatus for an induction motor, a desired quadrature-axis current i.sub.q * and a desired rotor flux .lambda..sub.r * are chosen. The desired quadrature-axis current i.sub.q * and desired rotor flux .lambda..sub.r * are related such that peak torque is produced by the motor per ampere of electric current flowing in the motor.

Abstract: The invention relates to a device for controlling the variation of the power and/or the speed of a load (2), such as an asynchronous, synchronous, universal motor, a transformer, an inductance, a condenser or a resistor, comprising a switch (5) placed on a phase (4) of a single-phase or multiphase alternating-current supply-circuit (3), this switch (5) being associated with means (6) for controlling the cyclic ratio .alpha./T in which .alpha. corresponds to the time of opening and closing of the circuit (3) by the switch (5) and T to the period of the phase (4) on which this latter is placed. In fact, the switch (5) is of the bidirectional MOS, IGBT or bipolar transistor switch type, this switch (5) being associated with means (9) for controlling the switching time, of the DRIVER type, capable of extending the switching time at closing so that it be within a range from 10 microseconds to 1 millisecond.

Abstract: A series universal AC/DC motor is controlled by switching the phase angle of an AC signal with a triac power switch in response to a motor control providing a phase-locked loop velocity control. A speed command circuit provides a reference frequency corresponding to a selected motor speed. The reference frequency is compared to a feedback frequency representing actual motor speed. An error signal representing the phase difference between the reference and feedback frequencies is compared to a ramp signal produced by the AC power source, and a resulting trigger pulse is used to control the triac power switch, thereby regulating the speed of the motor.

Abstract: A multiphase induction motor having concentrated phase windings utilizes adaptive torque control based on detection of asymmetry in the magnetic field density and corrective adjustment to restore symmetry based on voltage differences in the torque phase motor windings.

Abstract: An induction motor is operated at a high electrical efficiency level by employing a line current peak detector in conjunction with an electronic phase angle controller and a microprocessor system controller. If the line current peaks remain substantially constant the phase angle controller increases a phase gap in the applied line voltage to a width incrementally greater than a full-load value, at which point the line current peak value increases substantially. The increase in line current peak value is sensed by the line current peak detector and a signal is transmitted to the microprocessor system controller which in turn automatically adjusts the control input to the phase angle controller in order to incrementally decrease the existing phase gap in the output of the phase angle controller. Varying mechanical loads are therefore automatically accommodated while keeping the motor running efficiently.

Abstract: An AC synchronous motor control method in which the optimum phase advancing control is executed not only in acceleration but also in deceleration of a motor. When a value P, which is obtained by multiplying a motor's revolutionary speed by a torque command, is positive or equal to "0", a proportional constant of a linear equation for calculating a phase advancing compensation amount .delta. is set to k, whereas, when the above value P is negative, the above proportional constant is set to k' (k'<k). Then, the phase advancing compensation amount .delta. is calculated by using the proportional constant k or k', and the calculated compensation amount .delta. is added to a rotor phase .theta., thus advancing the phase of current commands. The motor is controlled by executing current loop processing on the basis of a current command T thus obtained.

Abstract: A dynamoelectric machine, for example, a brushless permanent magnet motor (M) has a plurality of stator windings (S) and a rotor (T) which rotates with respect to the windings. Apparatus (10) is provided for controlling winding commutation with respect to the rotor. A DC bus (14) supplies current to the windings. The current waveshape has characteristics which are a function of the commutation angle with respect to the windings. Current magnitude and waveshape are sensed by a sensing unit (22) and the sensed waveshape is sampled to obtain commutation information. An inverter (20) successively energizes and de-energizes the respective stator windings. A controller (26) obtains samples of the waveshape, and processes the information obtained by the sampling to control winding commutation. The controller controls the inverter operation to provide a commutation angle which optimizes motor performance and efficiency for a particular set of motor operating conditions.

Abstract: In an AC drive, a method for stator flux oriented control of a waveform generator providing switching signals to an inverter supplying pulse width modulated current to a three-phase, variable frequency induction motor is provided. The method includes generating a quadrature axis stator voltage signal, a direct axis stator voltage signal, and a stator frequency signal to which switching signals from the waveform generator to the inverter are responsive.

Abstract: The first, second and third switches within the first, second and third phases of a three phase motor controller are selectively operated to control the both the starting torque and the stopping torque of the motor. A preselected time delay before operating the switches within the individual phases allows the starting torque and the stopping torque to be controlled over a wide range of operation.

Abstract: A state observer driven by measurements of phase voltages and currents for estimating the angular orientation of a rotor of a synchronous motor such as a variable reluctance motor (VRM). Phase voltages and currents are detected and serve as inputs to a state observer. The state observer includes a mathematical model of the electromechanical operation of the synchronous motor. The characteristics of the state observer are selected so that the observer estimates converge to the actual rotor angular orientation and velocity, winding phase flux linkages or currents.

Abstract: An identity state observer for a smooth-rotor permanent-magnet synchronous motor is derived which reconstructs the electrical and mechanical states of the motor from current and voltage measurements. The observer operates in the rotor frame and estimates direct and quadrature stator currents, rotor velocity, and rotor position. Since the rotor position is estimated, the rotor reference frame is approximated using the latest rotor position estimate. The motor dynamics and the transformation into the estimated rotor frame are nonlinear and thus the observer and observer error dynamics are nonlinear. Therefore, small signal stability is analyzed from a linearized model. Simulations including realistic measurement disturbances are used to investigate the global stabilitiy and accuracy of the observer.

Abstract: A circuit for operating a polyphase dc motor includes first circuitry for determining when the back emf of the floating driving coils crosses zero. A first counter counts a time period between a first set of zero crossings, and a second counter is loaded with the count reached by the first counter. The second counter counts a time period between a subsequently occurring set of zero crossings. If the second counter reaches zero before the occurrence of a third zero crossing, a warning signal is generated. A method for determining if a deceleration rate of a polyphase dc motor exceeds a predetermined threshold includes measuring a first period between a first set of zero crossings of the back emf of the floating driving coils, and comparing the measurement of the first period with a subsequent period between a subsequent set of zero crossings. If the subsequent period is larger than the first period by a predetermined amount a warning signal is produced.

Abstract: A control system for an AC induction motor, comprising a stator, a rotor, at least two stator windings and rotor windings. The control system comprises a first vector rotator for rotating control signals with a first angle (.alpha.) for providing output signals connected to frequency inverters for providing drive signals to each stator winding of the motor, said first angle (.alpha.) being the time integral of a rotation frequency (w). Moreover, the control system comprises a second vector rotator for counterrotating measured drive voltages and/or currents with a second angle (-.alpha.) which is the inverse of said first angle (.alpha.). The rotation frequency (w) is controlled in dependence of said counterrotated measured voltages and/or currents essentially for maintaining the amplitude of said magnetizing currents (Im) of each stator winding constant which is a necessary condition for obtaining Natural Field Orientation.

Abstract: Improved techniques and circuit arrangements are provided for generating gating signals for firing the switching devices of an inverter circuit or like power electronics generator to generate harmonics of a fundamental frequency source and for providing an adjustable phase offset between the harmonic and the fundamental signals. According to a line-frequency signal modification method, a set of line-frequency sine wave signals disposed at equidistant phase angles are generated from a multi-phase fundamental input voltage. Firing pulses are produced from the line-frequency signals by accurately detecting the points of zero-crossings for the signals and subsequently detecting the overlapping segments of similar polarity between successive line-frequency signals. Two different schemes for conveniently generating the required line-frequency sine wave signals are present. According to a digital technique, a series of logic counters are used to generate the required M-phase, Nth-order harmonic gate timing signals.

Abstract: A circuit for controlling the velocity of the spindle motor in an electronic device using a disk is disclosed. Particularly, an abnormal rotation preventing circuit is disclosed which monitors the angular velocity of the spindle motor and forcibly controlls it to rotate within a predetermined velocity range when it deviates from the predetermined range. The duty value of a phase difference between two signals among first, second and third phase control signals for driving a three-phase motor is measured. Then, the phase difference is counted and the velocity is sampled. An abnormal rotation control signal is generated when the sampled velocity deviates from the predetermined range. The motor's velocity is then forcibly controlled so as not to deviate from the predetermined range, thereby preventing abnormal rotation of the motor.

Abstract: A current transformer (4) detects the output currents of a voltage-type inverter (INV), and comparators (6) check whether the outputs from the current transformer exceed a predetermined limit value. The detected output currents are fed to a vector analyzer (8) to determine the location of the output current vector. A zone determining circuit (9) determines the location of the current vector in the zones. An output pattern generating circuit (10) responds to the output from the zone determining circuit (9) and provides a switching pattern corresponding to the voltage vector nearest to a vector having the direction opposite to that of the output current vector. A selector (2), being controlled by the comparator (6), selects a switching pattern from the output pattern generating circuit and provides it to the inverter (INV), when the comparator (6) detects that the magnitude of the current vector exceeds the predetermined limit value.

Abstract: A control circuit for an induction motor calculates the d-axis current and q-axis current of a rotor in the motor and estimates the variation of the flux and resistance of the rotor on the basis of the d-q axis currents. As a result, a three-phase current for compensating for the resistance of the rotor varied due to the temperature and environment is suitably controlled to obtain high-performance of the motor.

Abstract: A phase voltage measuring device for an alternating current and a measuring method thereof for detecting a voltage from a main power supply Vcc supplied to a motor, wherein the voltage is converted to a digital signal which is multiplied by a basic pulse width modulation signal for detection of the phase voltage. A phase voltage measuring device and a measuring method have the advantage of measuring a phase voltage with a simple circuit by eliminating the problems associated with a conventional phase voltage measuring device which uses a current measuring coil and a pulse converter.

Abstract: Control circuit for semiconductor components of a converter circuit which can be switched on and off to convert direct current into three-phase current. The converter circuit is connected between a direct-current source and the stator of a synchronous machine having a cylindrical rotor. The control circuit measures rotor position and the direct current and determines from the obtained signals the value of the commutation angle .mu. of the phase current i in the converter at any value of the direct current I.sub.d on the basis of a model of the synchronous machine which solely takes account of the fundamental harmonic of the phase current i, the firing angle .alpha. of the semiconductor components being set between limits determined for any value of the direct current I.sub.d by the associated commutation angle .mu..

Abstract: An AC variable speed drive (VSD) system having a brushless doubly-fed motor receives power from an electric power grid at a system frequency of the grid and drives a mechanical load. The motor has a rotor with rotor windings and a stator with stator windings comprising first and second polyphase stator systems. The first stator system receives power from the grid at the system frequency. A sensor senses a parameter of the received power by the drive and produces a corresponding power sensor signal. A VSD controller receives and processes the power sensor signal and a reference signal which has been established according to a desired motor operation strategy, and generates therefrom a controller signal. A converter, such as a power electronic converter, receives and converts power from a converter powThis invention was made with government support under Grant No. 79-85BP24332, awarded by the Bonneville Power Administration. The United States government has certain rights in this invention.

Abstract: In a slip frequency control system hitherto widely employed as a control system for an induction motor type electric rolling stock (in which a slip frequency is determined from a current deviation, an inverter frequency is calculated from the slip frequency and a motor rotation frequency, and the inverter frequency is multiplied by a predetermined correction factor to determine a modulation rate, thereby operating an inverter), a motor output torque decreases in a low speed region. It is difficult to make the correction for this decrease of torque by detecting the torque. In the present invention made considering that a torque curve and sin .phi. (.phi.: the internal impedance angle of a motor) obtained from the result of simulation resemble each other, the decrease of sin .phi. is regarded as being the decrease of torque and a voltage to frequency ratio is corrected so as to compensate for the decrease of sin .phi..

Abstract: A three-phase converter for polyphase induction motors has an input transformer with primary windings and at least two secondary windings associated with each primary winding, and controlled power semiconductors. Groups of power semiconductors are connected to the secondary windings such that the power semiconductors operate in series with the motor phases.

Abstract: The invention relates to a process and apparatus for correcting a pre-controlled reference flux for a field-oriented control comprising a reference voltage model of a converter-powered multi-phase machine with a speed detection device. According to the invention, a comparison between a reference voltage which is used for setting a converter and a predetermined maximum converter output voltage provides a voltage control difference. From this voltage control difference, a flux control value is generated by a flux correction controller, which reduces the pre-controlled reference flux until the reference voltage for the converter is lower than or equal to the predetermined maximum converter output voltage (U.sub.wmax). As a result the field-oriented regulation never leaves the field-oriented range.

Abstract: A drive system for an automatic washer or dryer having a rotatable drum about a horizontal axis. An induction motor drives the drum and is connected to and disconnected from a source of alternating voltage by a microprocessor to control the speed of the motor. The microprocessor senses the zero crossing of the alternating voltage and the zero crossing of alternating current flowing in the motor to determine the time to connect the motor to the alternating voltage. The microprocessor analyzes successive readings of the motor's back emf to detect undesirable load distributions and effect redistribution.

Abstract: This invention relates to a motor current phase delay compensating method and apparatus thereof enabling the driven system to efficiently operate by compensating current phase delay of the stator coil winding such that an alternating current servo motor for driving a FA system, a CNC, or a robot for industry generates maximum torque. An output signal of an A/D converter and a rotational direction discriminating signal of an alternating current servo motor are received whereby a phase delay value with respect to the speed is generated. The phase delay value and an output signal from the A/D converter are summed whereby a phase delay compensation amount is computed to compensate the phase delay amount. The phase delay compensation amount and an output from the speed PI controller are respectively received whereby U-phase and V-phase analog current reference instruction values area generated.

Abstract: Method and apparatus for closed-loop microprocessor control of an electric motor having one or more phase windings and commutation of the phases by rotor/stator position sensors to provide improved efficiency in motor operation wherein the conduction angle of a phase energization of the motor at a given speed of operation is measured, the phase advance adjusted in a positive or negative direction to obtain a subsequent conduction angle, and the two sequential conduction angles compared. Based on the comparison, further phase advance and comparison of sequentially measured conduction angles is carried out, in positive or negative directions of phase advance, to maintain a minimum conduction angle and improve operating efficiency of the motor.

Abstract: An arrangement for detecting a motor overload condition by examining the phase angle relationship between the motor voltage and current. As the load increases, the phase angle difference approaches zero. By measuring the zero crossings of the voltage and current and providing a signal representative of the time difference between these crossings, the phase angle relationship is determined and, accordingly, so is the motor load. Specifically, a saturable ferromagnetic core is utilized to detect the current zero crossings.

Abstract: For operating electric drives, in particular of two-pole and multi-pole asynchronous induction motors intended for driving devices having at least two significantly different operating speeds it is proposed to operate at least one two-pole or multi-pole multi-phase asynchronous induction motor from a single-phase mains supply (L, N) by rendering conductive each of a plurality of power semiconductors (Triac T1, T2, T3) being connected in series to one of the windings (W1, W2, W3) each, only during a half wave of the single-phase supply voltage, in a manner staggered in time relative to the other series-connected semiconductor switches, and successively relative to the latter (FIG. 1).

Abstract: A system for controlling the start-up sequence of an electric motor includes a contactor relay for supplying polyphase operating voltage to the motor. A plurality of output circuits are respectively coupled between the motor and the relay contacts. Each output circuit is responsive to an output control signal applied to an input thereof for applying the operating voltage to the motor. An acceleration ramp generator is responsive to a motor control circuit which energizes the relay for providing a first signal which gradually rises upon the initial activation thereof. A phase control ramp generator is responsive to the application of the polyphase operating voltage to provide a second signal which decreases from a given level upon the initial application of the operating voltage. A plurality of comparators are provided each comparator having first and second inputs respectively coupled to receive each phase control ramp generator signal and the acceleration ramp generator signal.

Abstract: A control for an automatic washing machine with a reversing permanent split capacitor (PSC) drive motor. Separate ferrite core sensors surround each of two PSC motor windings. A sense winding is threaded through both sensors. A brief output voltage is generated whenever the alternating current in either PSC motor winding passes through a zero-crossing and when the sense winding is wound with proper mutual polarity, an output voltage is generated in response to zero-crossings of a brief, residual alternating current which flows in both PSC motor windings and the capacitor when the rotating PSC motor is cycled OFF.

Abstract: A control device for an electric vehicle having a reverse L type first filter circuit composed of a first filter reactor and a first filter capacitor between a current collector and control means for controlling electric motor of the electric vehicle. A second filter circuit composed of a series connected second filter reactor and a second filter capacitor is connected in parallel to the first filter capacitor. The second filter circuit has circuit constants selected such that a composite impedance of the second filter circuit and the first filter capacitor when viewed from the control means becomes small at a specific frequency.

Abstract: A method and apparatus directly regulate the output currents (i.sub.RX, i.sub.SX, i.sub.TX) of an inverter that feeds a predetermined number of induction machines. This method and apparatus is applicable to an inverter feeding one or more induction machines without rotational speed actual value sensors. The regulation is achieved by means of a secondary current control to which is supplied a current command variable system (i.sub.RW, i.sub.SW, i.sub.TW). According to the invention the current command variable system (i.sub.RW, i.sub.SW, i.sub.TW) is determined from the inverter output currents (i.sub.RX, i.sub.SX, i.sub.TX) and the state signals (S.sub.R, S.sub.S, S.sub.T) of the current switches of the inverter, from a calculation of the actual values of the active and reactive powers (P/U.sub.d, P.sub.q /U.sub.d) supplied to the motor, and a given rotational speed setpoint (n.sub.set), using field-oriented variables and simulating the actual rotational speed (n.sub.act).

Abstract: A drive system for an automatic washer or dryer having a rotatable drum about a horizontal axis. An induction motor drives the drum and is connected to and disconnected from a source of alternating voltage by a microprocessor to control the speed of the motor. The microprocessor senses the zero crossing of the alternating voltage and the zero crossing of alternating current flowing in the motor to determine the time to connect the motor to the alternating voltage. The microprocessor analyzes successive readings of the motor's back emf to detect undesirable load distributions and effect redistribution.

Abstract: A servo motor control apparatus effecting a feedback control of a servo motor according to an external operation command. The apparatus includes: an operational running state detecting unit for detecting a running state of the servo motor; a memory unit in which data representing inter-relation values are stored; a current value computing unit for computing an appropriate drive current value for the external operation comand; and a driving unit for driving the servo motor according to the computed appropriate drive current value.

Abstract: A current component, in which a phase angle is different by a predetermined reference angle from a magnetic flux occurring in an inductive load, is brought to a q-axis current. The q-axis current is computed on the basis of phase current. A phase angle of the magnetic flux is detected. A q-axis-current control phase and a reference potential phase are determined on the basis of the result of pulse-width-modulation computation and the phase angle. The q-axis-current control phase is controlled in a pulse-width-modulation manner. A potential of the remaining reference potential phase if fixed to a reference potential. Thus, interference among the phases is prevented to reduce current ripple.

Abstract: An electronic control for a motor which eliminates the motor centrifugal switch and more particularly a control for a domestic refuse compactor which permits the user to control the approximate full trash bag weight and obtain more compaction from a split phase induction drive motor. A ferrite core sensor on the main winding of the drive motor samples the lagging phase angle of the motor main winding current during a compaction stroke. A low force cycle is achieved by terminating the stroke as soon as phase samples fall below a threshold defined at the start of each cycle by a locked motor main winding phase sample acquired prior to starting the motor. A medium force cycle terminates the stroke when compaction forces exceed the main winding breakdown torque.

Abstract: An electrically powered suspension for a vehicle including a roadwheel and tire assembly, an electrically powered suspension unit having one end attached to the roadwheel and tire assembly and the other end attached to the chassis of the vehicle, with the suspension unit including an electric motor for positioning the roadwheel with respect to the chassis, and a controller for operating the electric motor so as to control the vertical movement of the wheel and tire assembly with respect to the vehicle's chassis. The electric motor may include either a linear or rotating electric motor, acting either alone or in parallel with a static load carrying device such as a fluid or coil spring.

Abstract: A PWM inverter apparatus used for driving an a.c. motor, including an inverter having an output part connected to the a.c. motor and switching elements on-off controlled by a PWM signal. The inverter apparatus also includes a part for receiving, at an interval of a given sampling period, status command information specifying a desired status of a vector of a rotating magnetic flux in the a.c.