International Rectifier Corporation

General Electric Company

Eddy Ying Yin Ho

Toshio Takahashi

Jun Honda

David C Tam

Yong Li

Anthony Michael Klodowski

Sidney Allen Barker

Craig William Moyer

Luis Jose Garces Rivera

A method for reducing audible motor noise in a motor drive, wherein the motor drive includes a motor controller driving a PWM space vector modulator providing gating pulses to an inverter providing phase currents to the phase windings of the motor, and wherein phase currents of the motor are determined by taking samples of the DC link current in a DC link powering the inverter. The method comprises determining the speed of the motor and comparing the speed to a preset threshold, the preset threshold defining a speed at which audible noise is generated by the motor due to a minimum pulse constraint being imposed on the motor phase currents in order to reliably sample the DC link current to measure the phase current. If the speed is below the threshold, the DC link current in the DC link is sampled using a reduced number of current samples for a PWM cycle of the PWM space vector modulator to reduce audible motor noise.

Audible noise reduction for single current shunt platform

A motor drive system for a sensorless motor includes a catch start sequencer that controls the motor drive system to robustly start the motor in the event the motor rotor is rotating in forward or reverse direction prior to activating the motor drive system. In particular, the catch start sequencer causes the motor drive system to initially find and track the rotor position, and then determines the speed and possibly the direction of rotation of the rotor. If the rotor is rotating in the reverse direction, the catch start sequencer controls the motor drive system to slow the speed of rotation and to then start the rotor rotating in the forward direction.

Method and system for starting a sensorless motor

An apparatus and method for estimating rotor angle information for the control of permanent magnet AC motors having sinusoidal current excitation. The disclosed motor drive can provide full load operation at very low speeds including zero speed without the use of a shaft position sensing device. The rotor angle is estimated through injection of high frequency current, and rotor angle is extracted by a signal-conditioning algorithm, which utilizes current amplitude differential to discriminate the rotor angle. Rotor angle magnetic axis orientation (North or South pole) at startup is detected by comparing time average current ripple (at signal injection frequency) content between two different levels of d-axis current injection.

Signal conditioning apparatus and method for determination of permanent magnet motor rotor position

A method and system for controlling a current regulator motor control for parking a motor rotor in a predetermined position, wherein a first current command and a first angle command are supplied to a current regulator for a first parking time, to move the rotor to an intermediate position; and a second current command and a second angle command are supplied to the current regulator for a second parking time, to move the rotor to a predetermined position. The current regulator may have a normal voltage output range, and a circuit may be provided for limiting a voltage output of the current regulator to a reduced voltage output range for at least a portion of the parking time. Advantageously the motor is a permanent-magnet synchronous motor with sinusoidal back-EMF.

Parking control technique for permanent magnet motor drives with sinusoidal BEMF

A motor drive system control provides global closed loop feedback to cooperatively operate system components to adaptively reduce noise and provide noise cancellation feedback. An active EMI filter reduces differential and common mode noise on an input and provides a noise level indication to a system controller. Power switches in both a power converter and power inverter are cooperatively controlled with dynamic dv/dt control to reduce switching noise according to a profile specified by the controller. The dv/dt control is provided as an analog signal to a high voltage IC and codified as a pulse width for a level shifting circuit supplying control signals to the high voltage gate drive. A noise extraction circuit and technique obtain fast noise sampling to permit noise cancellation and adaptive noise reduction.

Global closed loop control system with DV/DT control and EMI/switching loss reduction

A method and system for reducing audible motor noise in a system for reconstructing motor phase current from a DC bus current comprising current pulses on a DC bus in a PWM inverter motor drive system having a PWM cycle, and for controlling the motor, which forms a command voltage vector according to a space vector modulation arrangement for controlling the motor; measures the DC bus current on the DC bus supplying power to the inverter to reconstruct said motor phase current; and determines when the command voltage vector results in an inverter switching state that prevents the measuring of the DC bus current from accurately indicating motor phase current. During said inverter switching state, a current sampling scheduler applies a minimum pulse width constraint to said current pulses in said DC bus current to improve reconstruction of said motor phase current based on said DC bus current; and reduces the application of said minimum pulse width constraint to less than once per PWM cycle imposed by the PWM inverter motor drive system, thereby allowing motor phase current reconstruction with reduced audible motor noise. The current sampling scheduler synchronously samples said measured motor phase current to reduce errors in said measured motor phase current caused by said reduction of said minimum pulse constraint; reduces a bandwidth of said motor controller during said inverter switching state; and is adjustable in response to motor speed for setting the number of said minimum pulse width constraints per PWM cycle.

A method of determining a rotor angle in a drive control for a motor, comprising the steps of (a) determining a rotor magnetic flux in the motor; (b) estimating the rotor angle on the basis of the rotor magnetic flux; and (c) correcting the estimated rotor angle on the basis of reactive power input to the motor. Step (a) may include the step of non-ideal integration of stator voltage and current values. Step (b) may include the step of correcting phase errors caused by said non-ideal integration via a PLL circuit with phase compensation (F). Step (c) may include the steps of (1) calculating a first reactive power input value as 1.5*We*(C_Lq*I*I) and a second reactive power input value as 1.5*(Vq*id&#x2212;Vd*iq); (2) determining a difference between said first and second reactive power input values; and (3) applying said difference to the rotor angle estimated in step (b) to obtain a corrected rotor angle.

Rotor angle estimation for permanent magnet synchronous motor drive

A gate driver for a power switch, comprising a gate drive circuit coupled to the gate of the power switch for at least one of turning on and turning off the power switch; a gate voltage control circuit in the gate drive circuit for controlling a voltage applied to the gate of the power switch during at least one of turning on and turning off the power switch; and a signal supplied to the gate voltage control circuit indicative of a voltage rate of change per unit time to be applied in at least one of turning on and turning off the power switch.

A startup failure detection system provides an indication of motor startup failure based on a flux amplitude signal value. The flux amplitude signal is derived from motor flux estimations in combination with a rotor angle estimation. The flux amplitude signal value is compared to an upper and lower threshold value, and a startup failure is indicated if the flux amplitude signal value is outside the range determined by the upper and lower threshold value. The motor drive system can be set to attempt a restart when a motor drive startup failure is detected, with the retrial current, duration and the total number of retrials being user selectable.

Synchronous motor startup lock detection circuit and method

A DC offset compensation system and method significantly reduce a DC offset voltage in the voltage feedback loop of an AC motor drive control system. A control voltage error signal is demodulated and filtered and applied to the closed loop voltage feedback signals to compensate for DC offset voltages in the closed loop voltage feedback. A frequency discriminator tuned to the fundamental motor frequency improves the precision of the DC offset detection. A startup flux DC offset compensation operates to eliminate initial startup flux DC offset. Motor flux compensation is improved through a variable flux filter time constant.

System and method for elimination of DC offset feedback in AC drives

A method for detecting a loss of a phase in a multiphase rotating field machine, the method comprising providing a first electrical current into the machine windings to cause the current vector to assume a first current vector position, sensing a first current in at least one selected phase winding of the machine, comparing the sensed first current in the at least one selected phase winding with a first calculated current for the selected phase winding, and detecting that a first phase fault has occurred if the first calculated and sensed first currents differ by more than a predetermined value.

Phase-loss detection for rotating field machine

A technique for reconstructing phase currents based on measurements of a DC bus current. Non-observable regions of DC bus current samples to reconstruct phase currents are reduced in size by using two phase space vector modulation. The non-observable regions can be further reduced by omitting deadtime insertions for switch actuations when output current is higher than a given threshold. Voltage command vectors in non-observable areas can be constructed by two time averaged vectors one of which is constructed to obtain an observable DC bus current reflecting motor phase current. The additive vectors have the same combined time average value as that of the voltage command vector in order to preserve volt-seconds. Current samples may also be averaged to provide a more accurate reconstruction of phase current. Current samples are time delayed to avoid transients for more accurate readings. When three phase PWM inverter modulation results in inability to determine the motor phase current from the DC bus measurement, the technique includes dynamically switching to two phase PWM modulation to reduce the time interval when the motor phase current is not determinable through the DC bus current measurement.

Motor current reconstruction via DC bus current measurement

A method of determining a rotor angle in a drive control for a motor, comprising the steps of (a) determining a rotor magnetic flux in the motor; (b) estimating the rotor angle on the basis of the rotor magnetic flux; and (c) correcting the estimated rotor angle on the basis of reactive power input to the motor. Step (a) may include the step of non-ideal integration of stator voltage and current values. Step (b) may include the step of correcting phase errors caused by said non-ideal integration via a PLL circuit with phase compensation (F). Step (c) may include the steps of (1) calculating a first reactive power input value as 1.5*We*(C_Lq*I*I) and a second reactive power input value as 1.5*(Vq*id&#x2212;Vd*iq); (2) determining a difference between said first and second reactive power input values; and (3) applying said difference to the rotor angle estimated in step (b) to obtain a corrected rotor angle. At higher motor frequencies, the estimated rotor angle is based on the rotor magnetic flux. At lower frequencies, it is based on a predetermined motor load model which is used in conjunction with a start-up sequencing logic circuit.

Start-up method and system for permanent magnet synchronous motor drive

Global closed loop control system with dv/dt control and EMI/switching loss reduction

A method and system for modifying an estimated rotor angle for improved efficiency in a PMSM drive system. A module monitors a run command, a torque command, and an estimated speed; and in response thereto, generates an output correction angle for modifying the estimated rotor angle. The output correction angle may be added to the estimated rotor angle. The output correction angle may be generated only for predetermined conditions of said run command, torque command, and speed. In particular, the output correction angle may be generated (1) when the run command is asserted, (2) when the torque command is above a predetermined level, and (3) when variations in the speed are within predetermined limits.

Growing community of inventors

Torrance, CA, United States of America

Eddy Ying Yin Ho