71results about How to "Constant switching frequency" patented technology

A synchronized control method for a three-phase three-level boost-type rectifier with reduced input current ripple and balanced output voltages is disclosed. The proposed control allows simplifying the control circuit as much as possible without compromising the rectifier performance. In fact, besides simplicity, the control method featured synchronized command signals to de switching devices, minimized input current ripple, full controllability of the output voltage, dynamic balance of the output center point, constant switching frequency, simplified design of EMC filters, good transient and steady state performance, and low cost. The invention described first the most important configurations that the three-phase three-level boost-type rectifier may assume and studied the converter's operation. The concept involved for output voltage, input current, neutral point balance and control system design was presented.

The invention discloses a fault-tolerant control method for a five-phase fault-tolerant permanent magnet linear motor. Fault-tolerant current is calculated according to the rule that the magnetomotive force amplitude values and phase angles of rotation before and after the motor is faulted are constant and the current amplitude values of the normal phases are equal; two pieces of orthogonal basis of a fundamental wave space are obtained, and a park transformation matrix is deduced and popularized, so that coordinate transformation of voltage and current is realized; instruction voltage and inverted potentials of all the phases are summarized to obtain expected phase voltages of all the phases under a natural coordinate system of the motor; the expected phase voltages are modulated by a voltage source inverter CPWM to realize interference-free fault-tolerant operation after the five-phase fault-tolerant permanent magnet linear motor is faulted. On the premise of ensuring that the output thrusts or torques of the motor are consistent before and after a certain phase of the motor is in open-circuit fault, the motor thrust or torque pulse can be effectively suppressed; further, more importantly, the dynamic performance of the faulted motor is consistent with that of the normal motor, so that high-dynamic-performance fault-tolerant operation of the motor is realized, and the algorithm has certain universality.

The invention discloses a five-phase permanent magnet fault-tolerant motor direct torque control method based on novel pulse width modulation. The method comprises the following main steps: current and voltage components in a two-phase stationary coordinate system are obtained through coordinate transformation; through a PI regulator, given torque is obtained or the torque is directly given through an initial positioning method brought forward by the invention; an improved voltage method is used for estimating flux linkage, a voltage modulation ratio is obtained through a zero-sequence voltage harmonic injection-type pulse width modulation module, five-phase PWM waves are sent, and more accurate and smoother control is realized on the motor torque and the flux linkage. Compared with the traditional DTC, in the condition of keeping the dynamic response performance unchanged, the motor torque and the flux linkage pulsation can be effectively reduced, and the third harmonic content of phase current can be greatly reduced; and compared with SVM-DTC by adopting the SVPWM technology, sector judgment and voltage vector angle trigonometric function operation are not needed, the operation process is simplified greatly, and operation errors caused by trigonometric function operation are eliminated.

The invention discloses a short-circuit fault-tolerant vector control method for an embedded hybrid magnetic material fault-tolerant cylindrical linear motor. The short-circuit fault-tolerant vector control method comprises the following steps: building a five-phase embedded hybrid magnetic material fault-tolerant cylindrical linear motor model; compensating normal thrust missing caused by a short-circuit fault phase and suppressing a thrust ripple caused by phase short-circuit current with non-fault phase current of the motor; and obtaining expected phase voltage by adopting a series of coordinate conversion and voltage feed-forward compensation strategies, and achieving a fault-tolerant vector control after the phase short-circuit fault of the motor by a zero-sequence voltage harmonic injection-based CPWM modulation mode. According to the short-circuit fault-tolerant vector control method, the motor can suppress the thrust ripple of the motor under the condition of a phase short-circuit fault-tolerant operation; more importantly, the dynamic property, the steady-state performance and the properties in a normal state are consistent; the switching frequency of a voltage source inverter is constant; a CPU is low in overhead; and a natural coordinate system only needs to counterclockwise rotate a certain angle in any phase short-circuit fault, so that the motor fault-tolerant operation can be achieved.

The invention discloses a direct power control method of a modular multilevel wind power converter. The direct power control method includes: computing active power and reactive power through a virtual magnetic linkage, equaling a power grid to an ideal voltage source, combining the ideal voltage source with converter input reactance, equaling a grid-side power source to a virtual alternating-current motor, and considering that grid-side voltage is generated by the virtual magnetic linkage by sensing. Compared with a voltage-oriented double-closed-loop control method, the direct power control method does not need design of a current inner loop and is rapid in dynamic response; and compared with a look-up-table direct power control method, the direct power control method does not need a grid-side voltage sensor and is rapid in dynamic response, constant in switching frequency and better in steady-state characteristic.

The invention relates to a device and a method for direct torque control of a permanent magnet synchronous motor, belonging to the technical field of alternating current motor transmission. The device comprises the permanent magnet synchronous motor, a signal detecting circuit, a processor and an inverter. A current signal and a direct current bus voltage signal of the permanent magnet synchronous motor are respectively output to the signal detecting circuit which transmits the signals to the processor for processing so as to obtain a switch signal which is transmitted to the inverter for controlling the motor. According to a stator flux linkage amplitude error and an electromagnetic torque error, the device and the method respectively estimate a reference voltage vector in a stator rotating coordinate system, then convert the reference voltage vector into a stator biphase static coordinate system, and finally utilize a space vector modulation method to generate the switch signal for the inverter so as to control the permanent magnet synchronous motor. The device and the method adopt the space vector modulation method and substitute a proportional controller for a conventional hysteresis comparator so as to effectively reduce the pulsating movement of flux linkage and torque. The method adopted for voltage vector estimation is simple so that the structure of the control system can be simplified and easily realized.

The invention discloses a self-adaptive repetitive control method for an active power filter. The method comprises the following steps of: acquiring a power grid voltage signal and performing phase lock on power grid voltage; detecting a starting point of a fundamental period of the power grid voltage; recording a sampling point number K in the fundamental period of the power grid voltage; judging whether the sampling point number K changes or not; adjusting a repetitive control register parameter N according to the sampling point number K; and calling a corresponding number of count values to perform repetitive control calculation according to the repetitive control register parameter N. By the method, the problem that the compensation effect of the active power filter is unstable because of power grid frequency disturbance is solved.

The invention discloses an embedded type mixing magnetic material fault-tolerant cylindrical linear motor which comprises primary bodies and secondary bodies. The length of each primary body is smaller than that of each secondary body. An air gap is reserved between each primary body and the corresponding secondary body. Each primary body comprises armature teeth, fault-tolerant teeth and a coil winding. The 2*m armature teeth and the 2*m fault-tolerant teeth are uniformly distributed on each primary body, wherein m is the phase number of the motor and is larger than or equal to three; the armature teeth and the fault-tolerant teeth are arranged at intervals in a staggered mode. Only one set of disc-shaped coil windings are placed into an armature tooth groove of each primary body. No windings are arranged on the fault-tolerant teeth. The secondary bodies of the motor are made of mixing magnetic materials, a part of ferrite is used for replacing a part of rare earth permanent magnets to form four different mixing magnetic material structures, on one hand, the quantity of the adopted rare earth permanent magnets is greatly reduced, and the cost of the motor is reduced; on the other hand, as the magnetic energy product of the permanent magnets is reduced, the eddy-current loss of the motor is reduced greatly, and efficiency of the motor is improved.

The present invention relates to a direct torque control method for inhibiting torque ripples, mainly comprising the following steps: establishing an MC voltage vector switching table visually displaying degrees of change in torque and flux, and, proposing, on the basis of the MC voltage vector switching table visually displaying the degrees of change in torque and flux, an MC-DTC mark-to-space ratio computing policy for torque quantification control. The MC-DTC mark-to-space ratio computing policy allows for inhibition of torque ripples of a PMSM speed control system and for a constant switching frequency, uses the MC voltage vector switching table visually displaying the degrees of change in torque and flux, has a simple algorithm, does not reply on motor parameters, and obviates the need for rotational coordinate transformation.

The invention discloses a direct power prediction control method of a three-level grid-connected inverter model. The method comprises the following steps that 1) synthesis of three vectors is used in a three-level spatial vector modulation method, and an objective function is determined according to an instantaneous power theory and a direct power prediction control method; 2) a virtual vector is constructed, a large sector position where the virtual vector is positioned is determined, and a value of the virtual vector is calculated; 3) a small sector position where the virtual vector is positioned is determined; 4) action time of each of three vectors in the next switching period is calculated; and 5) and a switching sequence is determined according to balance of a mid-point voltage. The method is low in computational complexity, ripples of active and reactive power of the grid-connected inverter are low, the dynamic and static performances are high, and a harmonic wave inhibition effect is good.

The invention provides a single-phase power factor corrector in direct network-side power control. The single-phase power factor corrector comprises a power circuit, an auxiliary circuit and a control module, wherein the power circuit is used for completing single-phase AC-DC (Alternating Current-Direct Current) power conversion; the auxiliary circuit is connected with the power circuit, and is used for completing the instant detection of input voltage, input current and output voltage and the driving of an original PWM (Pulse-Width Modulation) pulse and outputting measured electric quantity to the control module; and the control module is used for carrying out digital operation and logical processing according to direct power control and a single-period control principle after various detection electric quantities of the auxiliary circuit are received, obtaining an original driving pulse, and finally completing power factor correction by virtue of the power circuit and outputting stable DC voltage. According to the single-phase power factor corrector provided by the invention, the single-phase AC-DC conversion of a network-side unit power factor is realized, and the single-phase power factor corrector has the advantages of quick response speed, strong anti-jamming capacity, capability of adapting to load change in a wider range and load following characteristics, and is an ideal single-phase power factor correction scheme.

The invention discloses a fault-tolerant field-oriented control method for non-adjacent two-phase short circuits of a five-phase permanent magnet-embedded fault-tolerant linear motor. Non-fault-phase fault-tolerant current is calculated according to the principles that pre- and post-fault traveling wave magnetomotive force is constant and the sum of non-fault-phase current is zero; a nonlinear strong coupling system of the motor in a fault state is converted into a first-order inertia system by employing an internal model controller, a first-order inertia feedforward voltage compensator and a counter electromotive force observer; non-fault-phase voltage commands are calculated on this basis and the voltage commands and counter electromotive force of various phases are added respectively to achieve fault-tolerant field-oriented control on the non-adjacent two-phase short circuits of the motor. Motor output thrust fluctuation caused by the non-adjacent two-phase short circuits of the motor is inhibited; fault-tolerant operation that one of the non-adjacent two phases is in an open-circuit fault and the other one is in a short-circuit fault can be achieved; more importantly, the dynamic property and the steady-state performance of the motor are consistent with those in a normal state; and a voltage source inverter is constant in switching frequency and has certain universality.

The invention discloses a five-phase permanent magnet embedded fault tolerant linear motor adjacent two-phase open circuit fault tolerant vector control method. Based on the principles that the magnetic motive force of traveling waves remains unchanged before and after a fault occurs and that the non-fault phase current sum stays at zero and taking the equality of the non-adjacent two-phase current amplitude as a constrained condition, the non-fault phase fault tolerant current is obtained to further deduce the generalized Clark transform matrix from the natural coordinate system of the non-fault phase to the two-phase stationary coordinate system. The non-fault opposite potential is observed by the transpose matrix of the transform matrix. A current internal model controller, a first-order inertial feed-forward voltage compensator and a counter-electromotive force observer are used to convert the nonlinear close coupling system of such motor under the condition of an adjacent two-phase open-circuit fault into a first-order inertial system. According to the invention, not only the thrust fluctuation caused by motor failure is restrained, but also more importantly, the dynamic performance and the steady-state performance are consistent with those under a normal condition to realize the fast response to non-overshoot and the stable switching frequency of a voltage source inverter.

A method for direct torque control of a dual-three-phase permanent magnet synchronous motor comprises the steps of: 1, construct a composite voltage vector to form a new switching table. 2, synthesizethat duty cycle of the vector; Step 3: Adjust the action sequence of the zero vector and the synthetic vector, and carry out the centralized treatment on the PWM waveform. The invention improves thetraditional direct torque control through the modulation of the synthetic vector and the duty ratio. The introduction of the synthetic vector can effectively reduce the harmonic current, and no additional harmonic plane current regulator is required. The calculation of the duty cycle is simple, and the torque ripple can be suppressed by adding zero vector in the control cycle reasonably. And in order to facilitate the hardware implementation of PWM modulation, the center symmetrical PWM waveform can be obtained by adjusting the sequence of vector action, and the switching frequency is constant.

The invention discloses a five-phase permanent-magnet embedded fault-tolerant linear-motor non-adjacent two-phase fault-tolerant vector control method. According to principles that magnetomotive forces before and after a two-phase open-circuit fault are invariant and a non-fault-phase current sum is zero, a condition that adjacent two phase current amplitudes are equal is taken as a constraint condition so as to derive and popularize a Clark transformation matrix; matrix transposition is used to estimate a counter potential; and an inner model controller, a first-order inertia feedforward voltage compensator and a counter potential observer are used to change a nonlinear strong coupling system of the motor under a fault state into a first-order inertia system. According to a principle that a synthesized magnetomotive force of a non-fault-phase short circuit compensation current and a short circuit fault phase current is zero, a short circuit compensation voltage is calculated. The voltage is superposed with an output voltage of a vector control device. By using the method of the invention, a motor thrust fluctuation caused by one phase short circuit and one phase open circuit of non-adjacent two phases of the motor is restrained, and dynamic performance and stable state performance are consistent with the performance under a normal state.

The invention discloses a five-phase permanent-magnet embedded fault-tolerant linear-motor adjacent two-phase fault-tolerant vector control method. According to principles that traveling wave magnetomotive forces before and after a two-phase open-circuit fault are invariant and a non-fault-phase current sum is zero, a condition that non-adjacent two-phase current amplitudes are equal is taken as a constraint condition so as to derive and popularize a Clark transformation matrix; matrix transposition is used to estimate a counter potential; and an inner model controller, a first-order inertia feedforward voltage compensator and a counter potential observer are used to change a nonlinear strong coupling system of the motor under a fault state into a first-order inertia system. According to a principle that a synthesized magnetomotive force of a non-fault-phase short circuit compensation current and a short circuit fault phase current is zero, a short circuit compensation voltage is calculated. The voltage is superposed with an output voltage of a vector control device. By using the method of the invention, a motor thrust fluctuation caused by adjacent two phase faults of the motor is restrained, dynamic performance and stable state performance are consistent with the performance under a normal state, and a switch frequency of a voltage source inverter is constant.

The present invention discloses a permanent magnet synchronous motor deadbeat torque prediction control method. Based on a permanent magnet synchronous motor mathematical model, an electromagnetic torque difference equation and a stator flux linkage amplitude square of a motor are derived, a system of linear equations in two unknowns formed by the two equations is solved to calculate the given motor stator voltage meeting the electromagnetic torque and the stator flux linkage deadbeat control. The system can achieve a motor electromagnetic torque and a stator flux linkage output following reference value in a control period. Compared to a traditional direct torque control method, the torque and the flux linkage response speed is faster, a space vector pulse width modulation policy is employed, the inverter switching frequency is constant, the torque flux linkage rippers are smaller, and the system loss is lower; and compared to a traditional deadbeat direct torque and flux control method, the computing amount is smaller, and the permanent magnet synchronous motor dead-beat torque prediction control method is easily achieved in the digital control system.

The invention discloses a back-stepping direct power control (DPC) method of a DFIG. According to the method, on the basis of combination of a back-stepping algorithm and a DPC technology, calculation is carried out by using a power reference value, an actual value, and a stator side voltage so as to obtain a reference value of a rotator side output voltage; and then modulation is carried out by a SVPWM module to obtain switching signals Sa, Sb, and Sc. The whole control process is carried out under a stationary coordinate system without the need of coordinate rotation and conversion; and independent and effective control of the active power and reactive power of the DFIG can be realized only by adjusting two adjustable parameters kp and kq, so that the control structure becomes simple. With inheriting of the excellent dynamic performance of the traditional DPC, the current harmonic wave and the power fluctuation can be reduced and the constant switching frequency can be obtained; and the good steady-state and dynamic performances are also realized.

The invention discloses a prediction control method of a constant switch frequency model of a tri-level grid connected inverter. The method comprises following steps of firstly, adopting tri-vector synthesis in a tri-level space vector modulation method, and determining a target function according to a transient power theory and a direct power prediction control method; step 2, according to the target function, taking the smallest value to determine a small section position where a reference vector is located; step 3, calculating respective action time of three vectors in one switch period; and step 4, according to central point voltage balance, determining a switch sequence. According to the invention, calculated amount of power control of the tri-level grid connected inverter can be greatly reduced; ripple waves of active power and reactive power of the grid connected inverter are reduced; better dynamic and static performance is achieved; constant switch frequency can be achieved; and good harmonic wave inhibition effects are achieved.

The invention discloses a variable-amplitude voltage vector selection method based on prediction control. The voltage vector amplitude enabling the evaluation function to be minimal is selected from the variable voltage vector amplitude so that the requirements of the torque and the flux linkage can be better met, and the required voltage vector can be synthesized through the space vector modulation technology. The torque ripple can be reduced and the switching frequency is constant.

The invention relates to a control method for a doubly-fed wind power generation system grid-side converter, and aiming at structure characteristics and control demands of the doubly-fed wind power generation system grid-side converter, provides a method for controlling predicted duty cycles of the doubly-fed wind power generation system grid-side converter. The method comprises the following steps: obtaining a three-phase voltage value and a three-phase current value of a power grid through a voltage and current sampling circuit, and obtaining a horizontal axis alpha component and a vertical axis beta component of the power grid voltage value, an axis alpha component and an axis beta component of the power grid current value under a two-phase stationary reference frame after coordinate transformation; obtaining a real-time phase angle theta(s) of the power grid voltage after the axis alpha component and the axis beta component of the voltage value are processed through a phase-locked loop, and determining three-phase optimal duty cycles da', db' and dc' through duty cycle equivalent reconstitution. The method provided by the invention is mainly used for controlling the wind power generation system grid-side converter.

The invention relates to the field of electronic technologies, in particular to a high-precision timer circuit used for a COT control mode DC-DC converter. The timer circuit is adjustable in on -time. The circuit comprises a proportion current generating unit, a high-precision frequency adjusting unit, a current arithmetic unit and a counter unit in a sequential connection mode. The timer circuit has the advantages that the on-time can be inversely proportional to input voltage and be directly proportional to output voltage; switching frequency is determined by resistance and capacitance and kept constant, and changes, caused by the technology and temperature excursion of the resistance, of a resistance value are offset; the constant switching frequency overcomes the defects that switching conversion of a traditional COT control circuit changes along with the output voltage, and EMI is not concentrated; in different application environments, the COT is adjustable.

The invention discloses a hybrid-excitation synchronous motor nonlinear reverse tracking control method. The method comprises the following steps of collecting signals from a motor main circuit and sending to a controller for processing; carrying out accurate initial position detection on a motor and acquiring a rotor position angle and an angular speed; converting a collected three-phase currentinto a d-q coordinate system; sending an angular speed tracking error, the angular speed and a direct current bus voltage to a speed reverse tracking controller, determining a motor operation intervaland calculating reference values of the motor in the different operation intervals; inputting a current tracking error and the angular speed into a current reverse tracking controller so as to calculate and acquire the reference values; and finally driving a main power converter and an excitation power converter. By using the hybrid-excitation synchronous motor nonlinear reverse tracking controlmethod, the system is designed simply, an adjustable parameter of the system is reduced, a motor torque ripple is small, a dynamic response capability of the motor is increased, and advantages of a low speed, a high torque and a wide speed regulation range of a hybrid-excitation synchronous motor are fully used.

The invention discloses a dead-beat torque control device, method and system. The dead-beat torque control method comprises the steps of receiving reference torque T*e, stator voltages [mu]<s[alpha]>and [mu]<s[beta]>, stator currents i<s[alpha]> and i<s[beta]>, stator resistance Rs, a discrete period Ts, stator self-inductance, rotor self-inductance and stator and rotor mutual inductance Ls, Lr and Lm, and a motor pole pair number p; calculating a stator flux linkage and a rotor flux linkage; calculating the torque of an induction motor at the moment k; calculating a torque angle of the induction motor at the moment k; calculating a torque angle increment; discretizing the stator flux linkage to obtain a stator flux linkage at the moment k and a reference stator flux linkage at the momentk; and calculating the stator voltage at the moment (k+1). According to the technical scheme, dead-beat control replaces a hysteresis comparator for direct torque control, and delay compensation is added, so that accurate tracking of the torque is achieved, the torque pulsation is reduced, and the switching frequency is fixed.

The invention discloses a direct power control method for current negative sequence component restraining under network unbalance. The direct power control method comprises the steps that three-phase voltage and three-phase current of a transformer are detected and transformed into a two-phase static coordinate system, T / 4 delay positive-negative sequence decomposition is carried out on two-phase static voltage and two-phase static current, active power and reactive power of a system are calculated, and the active power and the reactive power are predicted; compensation power in the two-phase static coordinate system is calculated when negative-sequence current needs to be zero, the negative-sequence current is made to be zero, and given active power and reactive power of the system are calculated; a conditional function is set up, an SVPWM positive-sequence voltage component is solved, an SVPWM negative-sequence voltage vector is determined, and an SVPWM voltage vector is output to a PWM rectifier. The direct power control method has the advantages that during a network unbalance fault, it can be guaranteed that the system is stable, response speed is high, design of a power filter is facilitated, the requirement for system sampling frequency is not high, and high robustness and good adaptability are achieved.

The invention discloses a control method and a control circuit of a switching circuit and the switching circuit. The control method comprises the following steps: setting an upper control threshold voltage and a lower control threshold voltage; wherein the upper control threshold voltage is the difference between the compensation voltage and the first slope, and controls the peak value of the inductive current of the switching circuit; the lower control threshold voltage being the sum of the compensation voltage and the second slope, and controlling the valley value of the inductive current ofthe switching circuit. The method is stable, and the response speed is high.

The invention provides a dual-sliding mode control based speed regulating system and method for direct torque of a permanent magnet synchronous motor main axis. The speed regulating method comprises the following steps: calculating the torque of the motor main axis according to the difference value of the actual rotating speed of the permanent magnet synchronous motor main axis and the given rotating speed of the permanent magnet synchronous motor main axis as a given value of a PI regulator; detecting the stator current and voltage of the motor main axis by using a sensor, observing the fluxlinkage and torque of the motor main axis under a stator coordinate system, comparing observed values with the torque calculated by the PI regulator and the given flux linkage respectively, obtainingdirect axis voltage and quadrature axis stator voltage by using the difference value through a dual-sliding mode controller, acting on a power switch device on a main circuit inverter through coordinate conversion and SVPWM conversion, and thus realizing direct torque control of the permanent magnet synchronous motor main axis. The speed regulating system is simple in structure, easy to realize and good in robustness, and has the advantages of high torque response speed and small tracking error, so that the stability of the system and the machining precision of parts are improved.

The invention discloses a hysteresis loop and carrier hybrid modulation method for a voltage inverter. The hysteresis loop and carrier hybrid modulation method is characterized in that: two phases of current in A, B and C phases of current are controlled based on two digital hysteresis loop comparators, and the third phase of current is controlled by adopting a carrier modulator; and the voltage inverter is a six-insulated gate bipolar transistor (IGBT)-based three-phase bridge inverter. In the method, not only the advantages realization simplicity, quick response and the like of hysteresis loop are maintained, and the advantages of switching frequency consistence and low current harmonic distortion of carrier modulation are integrated.

The invention discloses a dead-zone compensation method for parabolic current control. An adopted compensating circuit comprises a dead-zone compensator, a parabolic current controller, a PWM (Pulse-Width Modulation) signal generation unit and a driving circuit which are sequentially connected, and the dead-zone compensator is connected with a direction detection unit and an offset generation unit. The dead-zone compensation method for the parabolic current control comprises the steps that the direction detection unit is used for detecting output current direction of a converter to judge a rising or declining portion of current error signals needing to be adjusted; the offset generation unit generates the needed offset; the dead-zone compensator combines the output current direction and the offset to superpose corresponding offset on the received current error signals and generates improved current error signals; the parabolic current controller generates corresponding parabolic carrier waves according to the improved signals output by the dead-zone compensator, the PWM signal generation unit generates corresponding switch signals, on-off action of a bridge arm of a convertor is driven through a driving circuit, and an advanced time interval is set to be dead time to offset the influence of a dead zone.