127 results about "Dead time compensation" patented technology

A three-level inverter dead time compensation control method is used for compensating the decrease of system performance caused by dead time. According to the topological structure of a three-phase three-level PWM (pulse width modulation) inverter, the method first sets corresponding dead time and determines the on-off delays of power elements in the inverter; the method then considers the tube voltage drops of the power transistors of the inverter and the tube voltage drops of clamping diodes of the inverter and calculates the common voltage expression of the output neutral point of the inverter; afterwards, according to the sector with three-phase current value and a reference voltage vector, the method determines the relational coefficient between voltage error caused by the tube voltage drops of the power transistors, the tube voltage drops of the clamping diodes and the on-off delays of the power transistors and current, and thereby the total dead time compensation time of each phase of the three-level PWM inverter is worked out. The method takes the dead time, the on-off delays of the power elements and the tube voltage drops into full consideration, solves the problem of voltage and current distortion caused by the dead time effect in the three-level inverter, and enhances system performance.

The invention relates to a dead-zone compensation method for a voltage source inverter. The method comprises the following steps of: performing dead-time compensation according to the acting time t1 and t2 of two non-zero base voltage vectors in a pulse-width modulation (PWM) period Ts and the practical dead time Td of the voltage source inverter based on the conventional space vector pulse width modulation (SVPWM) modulation strategy; adding two dead-time compensation time tcom1 and tcom2 and the acting time t1 and t2 of the two non-zero base voltage vectors to obtain new acting time t11 and t22 of the two non-zero base voltage vectors in the PWM period; and operating the new acting time t11 and t22 of the two non-zero base voltage vectors by using the SVPWM modulation strategy to generate a needed PWM pulse and finally realize deal-time compensation and zero-current clamping effect inhibition.

An electric power converter which has improved accuracy in compensation of a dead time. A motor driving system employing the electric power converter is also provided. A power module includes a plurality of switching devices connected in series and converts DC power to AC power. A control circuit produces a voltage command value in accordance with a control command inputted from the exterior, and produces gate signals to drive the switching devices of the power module corresponding to a final voltage command value which is obtained from the voltage command value with dead time compensation. A dead time compensation logic circuit calculates a final dead time compensation voltage based on a change rate of the voltage command value, a gain (dead time compensation voltage value), and a polarity of a current, the gain being calculated from a DC voltage value supplied to the electric power converter, a dead time, and a switching frequency.

The invention belongs to the technical field of control of converters in distributed generation and energy supply microgrid systems and relates to an improved method for controlling direct current (DC) bus voltage of a two-stage converter. The method has the following beneficial effects: on the basis of two-closed-loop control of the conventional DC bus voltage outer loop and the inverter output current inner loop, two auxiliary control methods, namely inverter dead-time compensation and dynamic power feedforward, are added, wherein the impacts of the error voltage vector caused by the dead-time effect on the dynamic performances of the current inner ring can be effectively eliminated through the inverter dead-time compensation; and the dynamic power feedforward is a first derivative element and can ensure the current reference of the current inner loop to track power output of the preceding DC/DC module in real time; and by adopting the two auxiliary control methods, DC bus voltage surge and fluctuation in the transient state of the two-stage converter can be effectively suppressed and the dynamic responses of the two-stage converter can be improved.

A microcomputer includes a rotation angular velocity computation section, a feedback gain determination section, and a dead time compensation amount determination section. The rotation angular velocity determination section computes the rotation angular velocity of a brushless motor. Based on the rotation angular velocity, the feedback gain determination section determines feedback gains. The dead time compensation amount determination section determines a dead time compensation amount. The greater the absolute value of the rotation angular velocity, that is, the higher the rotation speed of the brushless motor, the greater the feedback gains determined by the feedback gain determination section become, and the higher the responsivity of the feedback gains becomes. The greater the absolute value of the rotation angular velocity, the smaller the dead time compensation amount determined by the dead time compensation amount determination section becomes.

An output current distortion compensating apparatus in an inverter is disclosed, the inverter including an inverter controller generating a PWM signal for controlling a PWM voltage generator, wherein the inverter controller includes a first dead time compensation voltage generator generating a compensation voltage based on an output current polarity of each phase in the inverter, and a second dead time compensation voltage generator generating a compensation voltage based on an output current waveform of each phase in the inverter, and wherein a first dead time compensation voltage outputted from the first dead time compensation voltage generator and a second dead time compensation voltage outputted from the second dead time compensation voltage generator are added to generate a final dead time compensation voltage, thereby preventing occurrence of hunting phenomenon in which a current is greatly fluctuated.

A dead-time compensation method is applied to a PWM inverter, which is provided to drive an induction motor using a constant V/f control. The method first calculates a root-mean-square current of the output instantaneous current of the inverter. Afterward, a lookup table of the root-mean-square current is used to obtain a dead-time compensation base voltage and a dead-time compensation per-unit voltage. Finally, the dead-time compensation base voltage is multiplied by the dead-time compensation per-unit voltage to produce a dead-time compensation voltage of the PWM inverter. Accordingly, the method reduces complexity of converting the current to the voltage to reach a faster real-time response. Furthermore, a more accurate dead-time compensation voltage is obtained without increasing hardware costs and the efficiency of operating the induction motor is improved at low speed and light load condition.

The invention relates to the technical field of alternating current servo vector control, and discloses a current loop control system based on an FPGA, and a servo device. According to the system and the device, through adoption of current loop control based on an FPGA hardware logic parallel processing mode, a current given quantity and signals sent by a current sampling module are input into a current controller module for PID calculation and decoupling compensation processing, a voltage vector reference value under a rotating coordinate system is output; a voltage vector reference value under a static coordinate system is output according to a rotor angle value output by an encoder feedback module and the output voltage vector reference value under the rotating coordinate system; a space vector pulse width modulation module converts the voltage vector reference value under the static coordinate system into three-way effective duty cycles; a complementary output pulse width modulation module with dead zone insertion converts the three-way effective duty cycles into six-way pulse width modulation square signals after dead-time compensation. Through adoption of the system and the device, the current loop control time is reduced, and the current loop bandwidth is improved.

A control apparatus for an electric power steering apparatus, including a dead time characteristic section that calculates a dead time characteristic value; a steering status determining section that determines a steering status; a gain section that varies a gain of the dead time characteristic value in accordance with a determination of the steering status; a polarity determining section that switches polarity determining methods in accordance with the determination of the steering status and determines a polarity on the basis of a detected current of a motor, a current command value or a model current; a temperature sensor that detects a temperature of an inverter; a dead time temperature correction value calculating section that calculates a dead time temperature correction value corresponding to the temperature; and a calculation processing section that calculates and processes the dead time temperature correction value with respect to a dead time compensation value with polarity based on an output of the gain section and outputs a dead time compensation value.

The invention relates to a vector controlled "dead-time effect" compensation method for a permanent magnet synchronous motor, and belongs to the technical field of permanent magnet synchronous motors,and solves the problems in the prior art such as compensation effect dependent on the accuracy of the motor model, need for additional hardware, complicated calculation and compensation by mistakes.The vector controlled "dead-time effect" compensation method for permanent magnet synchronous motor comprises the following steps: collecting phase currents ia, ib, ic of the permanent magnet synchronous motor; respectively comparing |ia|, |ib| or |ic| with a zero-cross threshold iH, if |ia|, |ib| or |ic| is less than or equal to the zero-cross threshold iH, performing the dead time compensation;otherwise, not performing the dead time compensation. The dead time compensation comprises steps of determining a voltage vector angle that needs to be compensated; calculating an average error voltage of the output phase voltages in a cycle, thereby obtaining the amplitude of the voltage to be compensated, applying a compensation voltage according to the voltage vector angle to be compensated andthe amplitude of the voltage to be compensated for performing a dead time compensation, so as to the accurate and fast dead time compensation.

The invention discloses a dead time effect compensation method and a dead-time effect compensation device. The method comprises the following steps of: presetting a mapping relation between an integer rotating speed point and a three-phase dead time compensation value to obtain a target three-phase dead time compensation value which corresponds to a current rotating speed point; adding the target three-phase dead time compensation value with a given three-phase duty ratio to obtain a practical three-phase duty ratio needed by compensation; and further obtaining a target three-phase SVPWM (Space Vector Pulse Width Modulation) parameter which corresponds to the practical three-phase duty ratio to generate a target three-phase SVPWM waveform so as to finish compensation for the three-phase SVPWM waveform under the rotating speed point. According to the method and the device, the problem that the current three-phase duty ratio of the three-phase inverter circuit output waveform of a motor controller is lower than the given three-phase duty ratio due to the presence of the dead time is solved, and the control efficiency of the motor controller is further increased.

The invention provides a dead-time compensation system which comprises a current sampling unit, an adaptive filter, a forward conversion unit, a low-pass filter, a reverse conversion unit and a dead-time compensation unit, wherein the adaptive filter is used for adaptively filtering each of sampled three phases of current to obtain a three-phase current forecast value; the forward conversion unit is used for executing 3/2 conversion and rotary conversion on the three-phase current forecast value; the low-pass filter is used for performing low-pass filtration; the reverse conversion unit is used for performing rotary reverse conversion and 2/3 conversion; and the dead time compensation unit is used for performing dead-time compensation according to the current subjected to 2/3 conversion. The invention also provides a corresponding dead-time compensation method. According to the invention, the adaptive filter can filter the sampled three phases of current, thereby overcoming an error between a detected value and a real value, which is caused by current detection delay and further avoiding failure of dead-time compensation caused by inaccurate detected current value.

A power converter configured to improve power capture in a wind turbine during low wind speed operation is disclosed. The power converter converts the power generated by the alternator of the wind turbine into a suitable AC current for delivery to a utility grid or to an electric load independent of the utility grid. The power converter is configured to operate in multiple operating modes, utilizing both synchronous and non-synchronous control methods, to extend the operating range of the power converter. During non-synchronous operation, the power converter utilizes a modulation routine that may either vary the dead-time compensation period during a constant modulation period or vary the modulation period with a constant on-time. A seamless transfer between non-synchronous and synchronous control methods with low total harmonic distortion (THD) improves the range of power generation for wind generators.

The invention discloses a novel method for compensating dead time of a converter, which is applied to universal voltage source converters. In the method, a distortion function correction step is increased on the basis of the normal method for compensating the dead time compensation. In the method, voltage feedback is used as a reference, and a dead time effect distortion function is corrected fora plurality of periods, so that the accuracy for dead time compensation can be effectively improved and the output quality of the converter is improved. The method is easy to implement and does not cause obvious disturbance to a converter control system.

An electric power steering apparatus of a vector control system converts calculated dq-axes current command values into 3-phase duty command values, driving-controls a 3-phase brushless motor by an inverter of a PWM control, and applies an assist torque to a steering system of a vehicle, wherein compensation signs of 3-phase current model command values in which the dq-axes current command values are converted into a 3-phase current command value model are estimated, wherein a dead time compensation amount is calculated based on an inverter-applying voltage, and wherein dead time compensation is performed by adding dead time compensation values that are 2-phase values converted from 3-phase values in which the compensation signs are multiplied with the dead time compensation amount, to dq-axes voltage command values, or by adding 3-phase dead time compensation values to 3-phase voltage command values.

The invention relates to the compensation of dead time effect in electronic appliances such as inverters or converters having one or more legs with two complementary switches. The invented method mainly includes following steps providing an initial pulse width modulated (PWM) reference, providing a bias current and detecting the bias current crossing points, providing a dead time compensation signal which is adjusted responsive to the crossing points, and adding the dead time compensation signal to the PWM reference. Hence an adaptive compensation is accomplished independent of types of switching elements and load conditions. A high reliable circuit with low cost is further included as a preferred embodiment of bias current crossing points detection.

The invention discloses a dead-time compensation method for an NPC-based three-level SVPMW (space vector pulse width modulation) rectifier. The method comprises the following steps: firstly, computing the general expression of a dead-time-free reconstitution voltage impulse by not considering tube voltage drop and the general expression of a dead-time reconstitution voltage impulse by considering the tube voltage drop to obtain a general expression of reconstitution voltage impulse compensation amount; then, selecting the general expression of the reconstitution voltage impulse compensation amount, which corresponds to three-phase voltage, according to the directions of all phase current and the timing sequence states of all phase voltages to work out voltage compensation amount; finally, feeding back the worked out voltage compensation amount to a reference voltage vector before being reconstituted, and performing compensation. According to the dead-time compensation method disclosed by the invention, by adopting a novel compensation amount selection method, the compensation amount is computed during a voltage reconstitution process, and compensation participated control is performed on the reference voltage vector; dead time and the tube voltage drop are fully considered, and therefore voltage and current distortion problem generated by the dead-time effect in the NPC-based rectifier is solved, and the system performance is improved.

The invention proposes a dead-time compensation method and device of an inverter and the inverter, and relates to the field of motor control. The dead-time compensation method of the inverter comprises the steps of acquiring a sampling current according to an output current of a three-phase inverter; determining a rotor position angle of the sampling current; determining a current vector phase angle of the sampling current; determining phase delay compensation quantity for compensating filtering delay; determining a phase of the sampling current according to the rotor position angle, the current vector phase angle and the phase delay compensation quantity; determining a phase dead-time compensation value by a predetermined compensation strategy according to the phase of the sampling current; and compensating a driving current of the three-phase inverter according to the phase dead-time compensation value. The acquired phase of the sampling current, acquired by the method, is more accurate, the determined phase dead-time compensation value is also more accurate, so that more accurate phase dead-time compensation value is obtained, and the dead-time compensation effect is further optimized.

[Problem]

An object of the present invention is to provide a vector control type motor control unit that compensates a dead time of an inverter without a tuning operation, improves a distortion of a current waveform and responsibility of the current control, and suppresses sound, vibration and a torque ripple.

[Means for solving the problem]

The present invention is the vector control type motor control unit that calculates a q-axis control assist command value, calculates dq-axes current command values from the control assist command value, converts the dq-axes current command values into 3-phase duty command values, and drives and controls a 3-phase brushless motor by a PWM-controlled inverter, wherein dead time compensation of the inverter is performed by calculating 3-phase dead time reference compensation values based on a motor rotational angle, calculating 3-phase dead time compensation values by temperature-correcting the 3-phase dead time reference compensation values, and adding the 3-phase dead time compensation values to 3-phase voltage command values after performing dq-axes space vector modulation.