Search Results (27)

This research explores a phase-shift-based discontinuous PWM method used for 24 V battery-powered onboard micro inverters, which are critical for thermally limited applications like micromachines, where efficient heat dissipation and compact size are paramount. Discontinuous pulse width modulation (DPWM) reduces switching losses by clamping the phase voltage to the DC bus in order to improve inverter efficiency. Due to the change in power factor at different operating points from motors or the inductor load, the use of only one DPWM method cannot achieve the optimal efficiency of a three-phase voltage source inverter (3ph-VSI). This paper proposes a generalized DPWM method with a continuously adjustable phase shift angle, which extends the six traditional DPWM methods to any type. According to different power factors, the proposed DPWM method is divided into five power factor angle intervals, namely [−90°, −60°], [−60°, −30°], [−30°, 30°], [30°, 60°], and [60°, 90°], and automatically adjusts the phase shift angle to the optimal-efficiency DPWM mode. The power factor is calculated by means of the Synchronous Reference Frame Phase-Locked Loop (SRF-PLL) method. The switching losses and harmonic characteristics of the proposed DPWM are analyzed, and finally, a 24 V onboard 3ph-VSI experimental platform is built. The experimental results show that the efficiency of DPWM methods can be improved by 3–6% and the switching loss can be reduced by 40–50% under different power factors. At the same time, the dynamic performance of the proposed algorithm with a transition state is verified. This method is particularly suitable for miniaturized inverters where efficiency and thermal management are critical. Full article

Model predictive control (MPC) is one of the advanced control strategies implemented for different applications to provide better performance and faster dynamic response. Modulated model predictive control (M²PC) is one of the recent MPC structures. It is developed based on the fixed switching frequency modulator and duty cycles concept, resulting in improved performance indicators under different operating conditions. In addition, one of the given PWM topologies that gained much attention due to higher switching frequency operation with similar power losses is discontinuous pulse width modulation (DPWM). Therefore, different M²PC methods including deadbeat control (DBC-M²PC) and cost function ratio (CFR-M²PC) have been implemented for low-inductance high-speed permanent magnet synchronous motor (PMSM) drives employing DPWM. The DBC-M²PC strategy shows a superior performance over the CFR-M²PC approach. Simulation analysis along with practical investigation through a dedicated high-speed testing rig are illustrated for both methods. Full article

With the widespread application of multilevel inverters, device losses have become a critical area of research. A key limitation of conventional three-level discontinuous pulse width modulation (DPWM) strategies is their inability to maintain switching device clamping during the peak intervals of the load current, especially under varying load power factor conditions, thereby reducing switching losses. This paper proposes an improved three-level power factor adaptive DPWM (PFA-DPWM) strategy that minimizes switching losses by clamping the power devices during the one-third fundamental period of maximum load current. First, a unified mathematical model of DPWM strategies is established. Theoretical analysis demonstrates that phase disposition (PD) carrier modulation for three-level inverter exhibits superior line voltage harmonic characteristics. Based on this, a theoretical comparison of switching losses and harmonic distortion for various DPWM schemes is conducted. The proposed PFA-DPWM control strategy has the minimum switching loss without compromising harmonic performance. The efficacy and validity of the proposed strategy are confirmed by comprehensive simulation and experimental results. Full article

This study investigates the efficiency and noise, vibration, and harshness (NVH) characteristics of electric vehicle (EV) powertrains based on three key Pulse Width Modulation (PWM) techniques: Space Vector PWM (SVPWM), Discontinuous PWM (DPWM), and Random PWM (RPWM). The objective is to evaluate the impact of these PWM techniques on inverter and motor efficiency, as well as their effects on NVH performance, particularly in relation to noise and vibration. Experiments were conducted across various speed and torque levels using a motor dynamo. The study reveals that DPWM provides the highest efficiency, outperforming SVPWM by up to 2.23%. However, DPWM introduces more noise due to increased total harmonic distortion (THD), negatively affecting NVH performance. SVPWM, on the other hand, offers a balanced trade-off between efficiency and NVH, while RPWM demonstrates comparable noise characteristics to SVPWM, with potential for broader harmonic distribution. The findings suggest that each PWM technique offers distinct advantages, and their selection should depend on the required balance between efficiency and NVH. Full article

In this paper, a sample voltage dead-beat control based on differentiative voltage prediction (DVP) and switching-cycle extension (SCE) is presented to achieve optimal transient response for DC-DC converters under discontinuous conduction mode (DCM) operation. Firstly, to improve load transient response, a DVP method is proposed to estimate the load. With the estimated load, the controller realizes load current feedforward and thus improves the transient response with a wide load range. Secondly, an SCE strategy is proposed to enlarge the output current range and output voltage slew rate, both of which have limited value under conventional digital pulse width modulation (DPWM). When the output current reaches the limited value, the proposed strategy increases the switching cycle to enlarge the current range without losing DCM operation. Finally, combining DVP with SCE, the converter not only achieves optimal response in large signal transients, but also doubles the load range in DCM operation. Full article

This paper presents a Markov chain random carrier frequency modulation (MRCFM) technique for suppressing sideband vibro-acoustic responses caused by discontinuous pulse-width modulation (DPWM) in permanent magnet synchronous motors (PMSMs) for new energy vehicles. Firstly, the spectral and order distributions of the sideband current harmonics and radial electromagnetic forces introduced by DPWM are characterized and identified. Then, the principle and implementation method of three-state Markov chain random number generation are proposed, and particle swarm optimization (PSO) algorithm is chosen to quickly find the key parameters of transition probability and random gain. A Simulink and JMAG multi-physics field co-simulation model is built to simulate and predict the suppression effect of the MRCFM method on the sideband vibro-acoustic response. Finally, a 12-slot-10-pole PMSM test platform is built for experimental testing. The results show that the sideband current harmonics and vibro-acoustic response are effectively suppressed after the optimization of Markov chain algorithm. The constructed multi-physics field co-simulation model can accurately predict the amplitude characteristics of the sideband current harmonics and vibro-acoustic response. Full article

Discontinuous pulse-width-modulation (DPWM) methods have been extensively used in the industrial area to reduce overall losses, which decreases the corresponding thermal stress on the power switches of converters. However, local thermal overload can arise due to different aging conditions of semiconductor devices or failure in the cooling system. This leads to reduced reliability of the converter system due to the low expected lifespan of the most aged switches or phase legs. In this paper, the modified DPWM strategies for independent control of per-phase switching loss are introduced to deal with this matter. The proposed per-phase DPWM techniques are generated by modifying the conventional three-phase DPWM methods for reducing the switching loss in a specific leg, whereas the output performance is not degraded. This paper reports on output performance, including output current total harmonic distortion (THD) and power loss of switching devices, analysis for the various modified DPWM strategies for independent control of per-phase switching loss, which is applicable in 2-level 3-phase voltage source inverters (2L3P VSIs). The results are compared to the corresponding continuous PWM technique to verify and analyze the effectiveness and accuracy of the modified DPWM strategies for independent control of per-phase switching loss. Full article

In this paper, a bidirectional grid-tied ZVS three-phase converter is proposed. The circuit operation principle in both the rectifier and inverter modes was analyzed. The proposed topology could achieve zero-voltage switching in the six main switches and the auxiliary switch both in the rectifier mode and inverter mode. In addition, the reverse recovery current of body diodes in the main switches was also suppressed. Furthermore, in order to realize the ZVS control scheme under the grid-tied bidirectional power flow condition and reduce the number of switchings, a modified carrier-based discontinuous PWM was proposed to fit the bidirectional switching sequence. Finally, a 3 kW prototype was constructed. Some simulation and experimental results are presented to verify the validity of the proposed circuit topology and PWM control scheme. Full article

This manuscript proposes a novel approach for determining phase and neutral-current-ripple RMS in grid-connected four-leg inverters with the neutral inductor. The harmonic pollution is determined for any arbitrary pulse width modulation (PWM) technique and a generic value of the neutral inductor. Thanks to the proposed approach, it is possible to describe the neutral inductor in a parametric way with respect to phase inductors and obtain a wide range of results, ranging from a direct neutral connection (no neutral inductor) to a conventional three-phase inverter (no fourth wire) for any value of modulation index and common mode injection. The results permit one to compare different design choices in multiple scenarios effectively. The findings were validated by numerical simulations and experimental tests employing the most popular PWM techniques, such as space vector PWM (SVPWM) and discontinuous PWM (DPWM). Full article

This study presents the characteristics and performance of a motor at the operating point based on pulse-width modulation (PWM). PWM is used in modulating the output voltage of a three-phase inverter. The PWM technique has advantages and disadvantages depending on the system size and operating range. For example, some discontinuous pulse-width modulation (DPWM) techniques are advantageous in low-cost systems because they can reduce the number of switches. Some PWM techniques are complicated for software construction and require a lot of computation. In this paper, PWM techniques were constructed by using the offset voltage injection method. Therefore, the construction of the PWM technique is simplified by the method. In an experimental setup, an interior permanent-magnet synchronous motor (IPMSM) and a three-phase inverter were implemented to test motor control performance depending on the PWM technique. In addition, the current control characteristics and inverter efficiency were analyzed and compared depending on the speed and load of the motor. According to the results of this paper, it is possible to compare the motor and inverter control characteristics using various types of PWM rapidly. Additionally, it will help to select an appropriate PWM technique for a specific system. Full article

Currently, silicon carbide (SiC) MOSFETs are several times higher in cost than the equivalent silicon (Si)-IGBTs; however, the gains in power conversion efficiency, simplification of thermal management, and energy savings in general bring the advantages of lower total cost of ownership. The implementation of discontinuous PWM (DPWM) techniques for controlling the motor drive brings further reductions for the semiconductor switching losses; however, most existing techniques have limited performance on the optimized clamping region, particularly at a low power factor, which is a common operation condition for motor drives employing the widely used $V/f$ control, particularly at partial- or low-load conditions. This paper evaluates the performance of a SiC-based two-level voltage-source inverter (2L-VSI) motor drive operated with generalized carrier-based PWM methods. Theoretical analysis and experimental measurements are conducted in a 2.2 kW heatsink-less 2L-VSI prototype and induction machine, which demonstrates that the minimum switching losses DPWM (MSL-DPWM) is the most favorable solution in practice in terms of the achievable power conversion efficiency and harmonic distortions and also produces the least common-mode current, which is critical in motor drives. Full article

In order to reduce the switching loss and cost, as well as improve the reliability of the induction motor (IM) drive system, the technology involving the three-phase current reconstruction of 60° discontinuous pulse width modulation (DPWM2) is studied in this paper. According to the analysis of the switching state for DPWM2 in different sectors, the three-phase current can be constructed by sampling the voltage of the DC-link resistor. When the target voltage vector is located near the sector boundary or in the low-modulation area, the duration of the active vector in the sampling period is less than the voltage sampling time, which leads to measurement errors of the DC-link current. Therefore, on the basis of the switching state in different unmeasured areas, a time compensation method combining phase shifting and frequency reduction is proposed, and the expressions for comparing values are derived. Lastly, a simulation model and an experimental platform are established to validate the accuracy of the proposed method. Full article

Continuous pulse width modulation (CPWM) and discontinuous pulse width modulation (DPWM) strategies are used to control voltage source inverter operation. CPWM strategies allow for the reduction of total harmonic distortion values, while DPWM strategies provide a more effective reduction in inverter switching losses. The paper is devoted to the problem of improving the three-phase voltage source inverter efficiency by a controlled transition from CPWM to DPWM. The article proposes an adjustable discontinuous pulse width modulation (ADPWM) method, which means a transition from space vector PWM (refers to CPWM strategies) to DPWM in all inverter phases when the switches’ temperatures exceed the allowable value in at least one of the inverter phases. The method flowchart is presented and an algorithm for modifying the envelope curve within one sector is given. In order to test the ADPWM method a Simulink-model of a three-phase voltage source inverter and its control system were developed. A study of the proposed ADPWM method’s efficiency in comparison with CPWM, PCDPWM and NCDPWM methods was carried out using a Simulink-model. It was established that the proposed ADPWM method provides dynamic losses reduction in the inverter switches by 2.86 times compared to CPWM and by 1.89 times compared to PCDPWM and NCDPWM methods. Power supply systems for medium and high-power AC motors provide a promising area for application of the proposed ADPWM method. Full article

The conventional DC-link type quasi-Z-source inverter has been known as a buck–boost inverter with a low component voltage rating. This paper proposes an active DC-link type quasi-Z-source inverter by adding one active switch and one diode to the impedance-source network to enhance the voltage gain of the inverter. As a result, the component voltage rating of the inverter is significantly reduced, which is demonstrated through some comparisons between the proposed topology and others. A discontinuous pulse width modulation (DPWM) scheme is proposed to control the inverter, which reduces the number of commutations compared to the traditional strategy. Under this approach, the insertion of a shoot-through state does not cause any extra commutations compared to the conventional voltage-source inverter. Details about control implementation, steady-state analysis, and design guidelines are also presented in this paper. Simulation and a laboratory prototype have been built to test the proposed inverter. Both buck and boost operations of the proposed inverter are implemented to validate the performance of the inverter. Full article

A full-bridge diode-clamped multilevel LLC resonant converter suitable for power conversion systems that use high input voltage, such as railway vehicles, is proposed in this paper. In order to eliminate the voltage deviations of the capacitors connected in series to the high voltage input DC link, a novel modulation strategy referred to as multi-neighboring reference vector discontinuous pulse-width modulation (MNRV DPWM) is proposed. Unlike the existing two-level resonant converter that varies the operating frequency to hold the output voltage constant, the proposed multilevel resonant converter modulates the amplitude of the fundamental wave input to a resonance tank while fixing the operating frequency at the resonance point. Therefore, the design of passive elements becomes easier, and stable operation is possible over a wide operating range with only one power conversion stage. In this paper, the control algorithm and operation characteristics of the newly proposed full-bridge diode-clamped four-level LLC resonant converter are analyzed in detail and design guidelines are presented. The feasibility of the proposed converter is verified through a simulation and an experiment with a prototype converter. Full article