Commutation Torque Ripple Reduction Research Articles

A Novel High-Voltage Gain Circuit Topology for Commutation Torque Ripple Reduction

The electronic commutation and the low inductance nature of the brushless dc motor (BLDC) deteriorate the expected performance. The ripples in the current waveshape are primarily due to the commutation of the phases, which is carried to produce a synchronously rotating magnetic field. This commutation ripples lead to mechanical pulsation and noise on the rotor side. This article presents a novel strategy for reducing the commutation torque ripple. The proposed topology uses a hybrid Ćuk voltage gain dc–dc converter at the front end, which has high voltage gain and which reduces voltage ratings of the dc supply. An auxiliary switch is connected across the dc link of the inverter to control the rate of rising incoming phase current during the phase change of the inverter with the help of the dc–dc converter. A prototype of a 1HP BLDC motor is used to validate the proposed topology both analytically and experimentally.

Effective Torque Ripple Reduction of Permanent Magnet Brushless DC Motor

To reduce commutation torque ripple, a model predictive control (MPC) for permanent brushless DC motors (BLDCM) is presented (CTR). Torque ripples cause vibration noise and decrease efficiency. The suggested MPC system is constructed by forecasting the phase current with the aim of minimizing the BLDCM's CTR and taking into consideration the CTR sources. The method presented in this paper is a unique methodology for suppressing CTR over the whole speed range, avoids more complex current controllers or modulation models, and overcomes the challenges of commutated-phase-current control. The ideal switching state is instantly selected and implemented during the next sample period according to the preset cost function in order to match the slope rates of outgoing and incoming phase currents during commutation, ensuring the minimum of commutation torque ripple. The modelling and experiment findings show that the suggested method can effectively reduce CTR over a wide speed range and achieve the better CTR minimization performance. The results are then compared to the outcomes of various torque ripple reduction(TRR) techniques.

Commutation Torque Ripple Reduction Strategy of Brushless DC Motor Drives Based on Boosting Voltage of DC-Link Small Capacitor.

Based on the brushless DC motor system with DC-link small capacitance powered by a single-phase AC power source, a boosting DC-link voltage strategy to reduce the commutation torque ripple of brushless DC motors is proposed in this paper. The control strategy utilizes the special topology of the motor system to boost the DC-link capacitor voltage in a specific zone during the non-commutation period. During the commutation period, the high voltage of the DC-link capacitor is released to meet the voltage requirement of the brushless DC motor during commutation. In order to reduce the commutation torque ripple and ensure the normal operation of the brushless DC motor, each rectifier cycle is divided into three zones according to the characteristics of the periodic change of the rectifier output voltage. Different operation modes are proposed for different zones. In DC-link capacitor boost voltage mode, the DC-link capacitor boosts the voltage to meet the voltage of the motor demand during the commutation period for achieving the purpose of reducing the commutation torque ripple. In this paper, the controller of the brushless DC motor system is designed and the experimental platform is built. The experimental results verified the correctness of the theoretical analysis and the feasibility of the proposed method.

Modeling of ZSI based BLDCM For Reduction of Commutation Torque Ripple

This paper proposes a new technology, which reduces ripple context in Brush less DC Motor. This technology is having the similar modulation modes in conduction period and commutation period. In Grid applications, Brush less DC motor produces a torque ripple, hence for the reduction of ripple content, a ZSI based BLDCM is proposed in this technology. The buck-boost property of a ZSI gives a effective reduction of the ripple content and also improves the DC voltage utilization. The MATLAB/Simulink/Simpower system were selected to design and implement a ZSI based BLDCM for less torque ripple content.

A new approach for commutation torque ripple reduction of FPGA based brushless DC motor with outgoing phase current control

ABSTRACT Brushless Direct Current Motor (BLDC) has been deployed across several kinds of applications. However, attaining a smooth torque ripple with fast response is relatively tough, as usually this is based on the varied slew rate line current in the commutation period. Hysteresis Current control has been widely used in earlier works for the maintaining incoming and outgoing phase current at the same rate throughout the commutation period. Additionally, this also helps in reducing the commutation torque ripple and delivers successful commutation. The proposed work here uses a relatively simple control technique that is primarily derived on the basis Outgoing-phase Current Discharge Hysteresis Control (OCDHC). This has been characterized to produce low response time and reduced torque ripple which has been suggested to execute in both conduction and commutation intervals. For the implementation of digital controller, we chose Xilinx Spartan 6 FPGA board. The digital controller algorithm is written using VHDL and is dumped on the FPGA. For this purpose we use Xilinx ISE and iMPACT tools. FPGA receives hall sensor output and current from BLDC motor with reduced torque ripple and generates the gate pulses which drive the IGBT switches using OCDHC control. This condition shows that the performance of the system is not primarily based on the motor parameters, excluding the stator resistance. Lastly, results obtained from the simulation and experimental results validate the significance of the proposed control technique based on response time at load conditions that vary at different junctures.

Improved PWM-OFF-PWM to Reduce Commutation Torque Ripple of Brushless DC Motor Under Braking Conditions

This paper proposes an improved PWM-OFF-PWM of the brushless DC motor under braking condition which can reduce commutation torque ripple. Compared with other brake modulation methods, PWM-OFF-PWM can restrain non-commutation torque ripple attributed to non-conductive freewheeling, while incapable of suppressing commutation torque ripple at low speeds effectively. Therefore, to solve commutation torque ripple caused by the turn-off time being shorter than turn-on time, an improved PWM-OFF-PWM is proposed in this paper. Moreover, to describe the influence factors of commutation torque ripple, the formulas of the duty cycle of switching tube in the commutation period and that during non-commutation period is derived. We can conclude from mathematical analysis that when duty cycles of outgoing and incoming phases satisfy derived formula, the non-commutation current in commutation interval will be more stable, which can contribute to suppress the commutation torque ripple at low speed under PWM-OFF-PWM mode and to improve the operation stability of BLDCM. The correctness and feasibility of the proposed method can be proved by simulation and experimental results.

Evaluation of Predictive Current Control Techniques for PM BLDC Motor in Stationary Plane

In general, PM BLDC motors are injected with square wave phase currents through PI-PWM control in a-b-c reference plane to ensure maximum torque-per-ampere. The operation of PM BLDC motor in a stationary plane has shown considerable simplification in design, and analysis in the control techniques. The present paper considers the injection of square wave phase current through predictive current control strategies in the stationary plane. For the evaluation of performance, cases of deadbeat predictive control, hysteresis based predictive control, and finite control-set model predictive control (FCS-MPC) methods are considered. Control schemes have been designed for 48V, 660W PM BLDC motor. Comparative evaluation is carried out in terms of the harmonic components available in the current and torque, tracking of the current trajectory in the stationary plane in the low and high-speed region, and execution time of all the control methods. Considered predictive methods are tested on an experimental prototype, and control is implemented through digital Signal Processor (DSP) TMS320F28335. Evaluation leads to the conclusion that predictive control performs better than PI-PWM for reducing commutation torque ripple, keeping current harmonics under control. It is observed that predictive control strategies in the stationary plane, improve the torque-speed characteristic to the wider utilization of constant torque zone of operation as compared to conventional strategies.

Commutation Torque Ripple Suppression Strategy of Brushless DC Motor Considering Back Electromotive Force Variation

This paper presents a commutation torque ripple suppression strategy for brushless DC motor (BLDCM) in the high-speed region, which considers the back electromotive force (back-EMF) variation during the commutation process. In the paper, the influence of actual back-EMF variation on the torque and outgoing phase current during the commutation process is analyzed. A modified smooth torque mechanism is then reconstructed considering the back-EMF variation, based on which a novel torque ripple suppression strategy is further designed. Compared with the traditional strategy which controls the chopping duty cycle relatively smoothly in the commutation process, the proposed strategy dynamically regulates the chopping duty cycle, which makes it show a gradual decrease. This strategy can suppress the commutation torque ripple even in a long commutation process, and broaden the speed range of the commutation torque ripple reduction. Under the experimental conditions of this paper, the proposed strategy can effectively reduce the commutation torque ripple in the high-speed region, and avoid the outgoing phase current cannot be reduced to zero. The experimental results verify the correctness of the theoretical analysis and the feasibility of the proposed strategy.

A simple constant switching frequency of direct torque control of brushless DC motor

This paper discusses about direct torque control of Brushless DC motor by injecting the triangular waveform and using PI controller in order to reduce the torque and obtain constant switching frequency. Brushless DC motor are widely used in applications which require wide range of speed and torque control because of robust, longer lifespan, faster torque response and able to operate at high speed. Unlike conventional three phase DTC of induction machine (IM),the proposed DTC approach introduces two phase conduction mode. Besides that, the magnitude flux is considered constant in which the results only gains from constant torque region. Thus, the flux control loop is eliminated while implement this scheme. Using the triangular waveform that will be compare with actual torque, the proper switching pattern can be selected to control the generated torque and reducing commutation torque ripple. The torque response depends on the speed of the stator flux linkage which is directly controlled by selecting appropriate voltage space vectors from a look-up table to make sure the torque error within the band. The validity of the proposed control scheme for constant switching frequency and reduce torque ripple are verified through simulation and experimental results.

Commutation Torque Ripple Reduction for Brushless DC Motor Based on an Auxiliary Step-Up Circuit

There exists torque ripple in the commutation process of brushless DC motor (BLDCM), which seriously restricts its application in the high-performance field. This paper proposes an auxiliary step-up circuit to suppress the commutation torque ripple of BLDCM, and the auxiliary step-up circuit consists of a transformer, a capacitor and a switch circuit. For effective suppression of the commutation torque ripple, the capacitor is charged in the non-commutation period. When the commutation occurs, the charged capacitor is added on the power source through a switch circuit to step up the dc-bus voltage in the commutation period, and the three-phase inverter is regulated to make the motor’s input voltage is equal to four times the back electromotive force (back EMF) amplitude. The auxiliary step-up circuit only transfers partial power required in the commutation process of the motor, and the capacity of the power components is reduced accordingly. The inductive energy stored in the transformer is returned to the power source in each switching cycle, which improves the energy utilization rate. In addition, this method can also shorten the commutation time. The validity and effectiveness of the proposed method is verified through experimental results.

Commutation Torque Ripple Suppression Strategy for Brushless DC Motors With a Novel Noninductive Boost Front End

This paper first presents a novel boost front end simply with a diode, a MOSFET, and a DC-link capacitor. Without extra inductors or other power components, the boost font end could boost the capacitor voltage with the motor stator inductances, thus reducing the influence of the limited DC-link voltage on commutation torque ripple reduction to a large extent. A unified commutation torque ripple suppression strategy is further proposed with the front end adopted based on the analysis about the effects of four switching vectors on motor speed regulation and DC-link capacitor voltage regulation. The proposed strategy can boost the DC-link capacitor voltage via properly selection of switching vectors under the premise of guaranteeing normal speed regulation in noncommutation period, and reduce both the commutation torque ripple and commutation time by two consistent switching vectors with the boosted DC-link capacitor voltage in commutation period. Finally, the proposed method is theoretically analyzed with respect to the capacitance selection and the boot capacity of noninductive boost front end. The correctness of the analysis and the effectiveness of the presented method are validated by the experimental results.

Improved Control of BLDCM Considering Commutation Torque Ripple and Commutation Time in Full Speed Range

The three phases of brushless dc motor (BLDCM) are involved in energy conversion during the commutation interval. A novel commutation analysis method of the BLDCM based on coordinate transformation theory is proposed in this paper, though this coordinate transformation theory is popular in the control of three-phase sinusoidal motors, such as induction motors and permanent magnet synchronous motors. The method is intuitive and easy to understand compared with the method based on circuit solving. Combined with the voltage vector diagram of the inverter, commutation control to reduce commutation torque ripple under low speed (LS_RCTR) and high speed (HS_RCTR) is deduced. However, under a heavy load and high-speed condition, long commutation time may result in commutation failure if these commutation controls to RCTR is adopted. To avoid that, commutation time must be controlled. Then, commutation control to reduce commutation time under low-speed (LS_RCT) and high-speed (two cases, named HS_RCT1 and HS_RCT2) are proposed. The improved control of BLDCM presented in this paper can coordinate commutation torque ripple and commutation time in full speed range. Finally, the feasibility and effectiveness of these methods are verified by experiment.

Multimode Current Hysteresis Control for Brushless DC Motor in Motor and Generator State With Commutation Torque Ripple Reduction

Nowadays, studies of the control of brushless dc motor (BLDCM) are mainly focused on motor state. However, it may also work in generator state. Current hysteresis control (CHC) is very suitable for the motor control, because it can directly control current. In this paper, a multimode CHC for BLDCM in motor and generator state is presented. It can not only complete commutation successfully but also reduce commutation torque ripple. Moreover, a novel transition control method based on the background of CHC with fast response is proposed to carry out commutation and the transition processes simultaneously. Finally, the effectiveness and insensitivity to the parameters of the proposed control algorithm are verified by experiments.

Finite Control-Set Predictive Power Control of BLDC Drive for Torque Ripple Reduction

Due to advantages as high efficiency and high power density, brushless direct current (BLDC) motor has been used in a wide variety of applications. However, in conventional 120o conducting drive operation it develops significant torque ripple as a result of phase commutation. To reduce torque undulations, in this paper is proposed a power control based on Finite Control-Set Model based Predictive Control (FCS-MPC). The relationship between the control of the power delivered to rotor and torque ripple reduction is presented. The effectiveness of commutation torque ripple reduction of proposed method is presented in comparison with conventional torque control strategy. The results of proposed predictive control approach demonstrate fast torque response with no adjustable gains needed and operates with model variables on stationary reference frame.

Commutation Torque Ripple Reduction of Brushless DC Motor in Braking Operation

In this paper, the commutation torque ripple is studied in the brushless DC motor (BLDCM) braking operation. As the phase currents flow in the reversed directions in the braking operation, the current circuits in the braking operation are different from those in the motor operation. For this reason, it is found that the commutation torque ripple can be reduced in the speed range from the rated speed to zero just by the common braking pulse width modulation strategies, where the three-phase modulation is not needed. However, it is impossible in motor operation. Under the common braking pulse width modulation strategies, the speed ranges where commutation torque ripple can be reduced are derived and compared. Based on the analysis of these speed ranges, a simple braking method is proposed. With this method, the BLDCM can be slowed down without commutation torque ripple in the whole braking process from the rated speed to zero. Experiment results verify the effectiveness of the method and the correctness of the theory.

A simple overlap angle control strategy for reducing commutation torque ripple in a brushless DC motor drive

A commutation torque ripple is generated in a brushless DC motor due to a finite time taken for current transfer between outgoing phase and incoming phase due to the phase inductance. The effect of commutation ripple will be more severe for low voltage high current BLDC drives used for automotive applications. Direct Torque Control (DTC) techniques are used to reduce the torque ripple. Two phase conduction with six voltage space vectors and three phase conduction with twelve voltage space vectors with DTC are used to reduce the torque ripple. Twelve Step DTC (TSDTC) is capable of reducing torque ripple considerably but at the cost of increased inverter and winding losses. In Six Step DTC (SSDTC) the torque ripple is higher than that of TSDTC but with reduced winding and inverter losses. In this paper an attempt has been made to strike a balance between torque ripple and losses. A novel Direct Torque Control with twelve voltage space vector with overlap angle control has been proposed. The proposed method is validated through simulation and experimental results.

A Novel Method of Reducing Commutation Torque Ripple for Brushless DC Motor Based on Cuk Converter

In this paper, based on Cuk converter, a novel commutation torque ripple reduction strategy is proposed for the brushless DC motor. Output modes (buck–boost mode and boost mode) of the Cuk converter during the commutation period and normal conduction period are altered by designing a mode selection circuit, which can reduce commutation torque ripple over the entire speed range. During the commutation period, Cuk converter operates in the boost mode to step up the input voltage of three-phase bridge inverter and then meet the voltage demand of commutation period, such that the commutation torque ripple can be reduced by keeping the noncommutated current steady. In order to improve the utilization rate of the converter, during the normal conduction period, Cuk converter operates in the buck–boost mode and the input voltage of three-phase bridge inverter is regulated by adopting the pulse amplitude modulation (PAM) method without the inverter pulse width modulation chopping, which can reduce the voltage spike damage to the motor windings caused by turn-on/off of MOSFET in the inverter and simplify the program of modulation method further. The experimental results verify the correctness of the theory and the effectiveness of the proposed approach.

Commutation Analysis of Brushless DC Motor and Reducing Commutation Torque Ripple in the Two-Phase Stationary Frame

The control of brushless dc motors (BLDCMs) is similar to dc motors during the noncommutation interval. However, three phases are involved in electromechanical energy conversion during the commutation interval, making the control of the BLDCM similar to a three-phase ac motor during the commutation interval. A novel commutation analysis method for BLDCMs is proposed based on the coordinate transformation theory, which is used in control of a three-phase ac motor usually. The model of the BLDCM during the commutation interval is acquired in the two-phase stationary frame by using the Clark transformation. The commutation control method for suppressing commutation torque ripple and shortening the commutation time are obtained. Finally, the feasibility and effectiveness of the method is verified by experimental results.

A switched current controller with commutation delay compensation for the reduction of commutation torque ripple in BLDCM drives

A switched current controller with commutation delay compensation for the reduction of commutation torque ripple in BLDCM drives

A new approach for minimizing torque ripple in a BLDC motor drive with a front end IDO dc-dc converter

This paper proposes a front end integrated dual output (IDO) dc-dc converter for commutation torque ripple reduction in a permanent magnet brushless DC (BLDC) motor drive. The current ripple owed to the inductance and resistance of the motor during commutation instant results in torque ripple. In this work the dc link voltage of the converter is varied at commutation instants to minimize current ripple and hence torque ripple. The wider output range and faster response of the IDO converter make it a suitable choice as a front end converter for minimizing torque ripple. Simulation results validate the proposed converter for the BLDC motor drive. Experimental analysis of a conventional drive is performed to verify the simulation results.