共查询到20条相似文献,搜索用时 31 毫秒
1.
系统旨在设计一种D类功率放大器,以高频三角波作为载波,对音频信号进行采样,生成PWM(Pulse Width Modulation)调制信号.采用高速开关管组成的互补对称式H桥电路对信号的功率进行放大,再将放大后的信号送入4阶Butterworth低通滤波器进行滤波,得到理想的音频信号.系统主要针对音频信号进行处理,对输入频率20 Hz~20kHz,振幅30~250 mV的音频信号可以实现很好的功率放大效果,最大不失真输出功率大于1W,最高效率可达到83%.还能对输入信号进行可调放大,实现信号输出功率可调. 相似文献
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Bor-Jehng Kang Chang-Ming Liaw 《Industrial Electronics, IEEE Transactions on》2001,48(5):956-967
Hysteresis current-controlled pulsewidth modulation (PWM) is very robust but it possesses nonconstant switching frequency, and it is difficult to use for high-performance position servo applications. This paper presents a robust hysteresis current-controlled PWM scheme for a magnetic suspended positioning system driven by an inverter-fed linear permanent-magnet synchronous motor having improved performance in these two areas. In the proposed control scheme, the conventional hysteresis PWM mechanism is augmented by a robust harmonic spectrum-shaping controller. The error signal, which represents the switching frequency deviated from the set one, is detected using a notching filter inverse model. Then, the current command is adjusted by a robust compensation signal. The hysteresis band can be equivalently varied to let the dominant harmonic frequency of inverter output be constant, wherein the frequency can easily be changed by tuning the center frequency of the notch filter. The gating signal of switches is not needed to be sensed for making the proposed control. The constant-frequency control performance yielded by the proposed controller is rather insensitive to the system disturbances and the neutral voltage variation due to isolated Y connection. Through applying the proposed PWM inverter, satisfactory position control requirements can be achieved by properly setting the dominant harmonic frequency according to the electromechanical model of the positioning system 相似文献
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Jalili K. Weitendorf N. Bernet S. 《Industrial Electronics, IEEE Transactions on》2008,55(3):1035-1046
This paper investigates the effects of grid voltage distortions caused by thyristor converters on the steady-state performance of a pulsewidth modulation (PWM) rectifier with dc voltage link for low-voltage applications. The disturbance transfer function of the current control loop is used to analyze the effects of grid distortions. Influences of the current controller, the phase-locked loop parameters, and the filter inductance on the generated current harmonics are presented. For existing grid voltage harmonics, the amplitude of the corresponding current harmonics are determined and compared to measured current harmonics using a 400-V 40-kW test bench consisting of a PWM rectifier with voltage dc link parallel to a 40-kW thyristor converter. 相似文献
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This paper deals with a suppression method for the resonance oscillation in the ac side of a pulse-width modulation (PWM) current source converter. The converter is operated with the PWM switching pattern which is generated by the full digital control of computer software. The resonance current, caused by the LC low pass filter at the step change of the pattern, can be effectively suppressed by one pulse control of the pattern. The proposed method does not need to have the feedback loop of the current/voltage and does not offer the switching stress of the devices. The switching timing of the control is determined by pre-calculation of the off-line in consideration of the circuit constants. The experimental and the simulated results in the single-phase and the three-phase PWM converters are given, compared with those without the control, and show good response of the supply current. 相似文献
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Martins J.F.A. Pires A.J. Silva J.F. 《Industrial Electronics, IEEE Transactions on》1998,45(5):802-804
A new feedback current controller for three-phase pulsewidth modulation (PWM) power inverters is presented. To achieve robustness, fast dynamical response, reduced switching frequency, and simple hardware implementation, an improved three-level hysteresis sliding-mode controller is used. All voltage vectors are accurately selected in order to minimize the current error 相似文献
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A SPICE simulation model of current-mode pulse-width modulation (PWM) converters operating in the continuous mode is described and tested against analytical expressions and experimental data for buck and boost converters. The simulation model is also used to compare an earlier average model to a recently suggested modification and to examine the effect of the gain factor in the current feedback path 相似文献
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A novel approach to filter design for a closed-loop, pulse-width-modulated (PWM) DC-AC inverter system driving an RL load is investigated. The system has a rectangular hysteresis in the forward path and it is closed by current feedback. When it is excited by a sinusoidal input reference, it provides square pulses that produce a nearly sinusoidal current in the load. Using a describing function technique, design equations for the filter are derived. The data needed for the filter evaluation are the amplitude of current ripple and the frequency of square pulses delivered by the power bridge. System simulation and experimental results show that the design of the filter can be based on the method proposed and that the filter can provide a significant reduction of current ripple, or otherwise a significant reduction of switching frequency 相似文献
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Aiguo Xu Shaojun Xie 《Power Electronics, IEEE Transactions on》2009,24(5):1233-1242
Multipulse converters are suitable for high-power application with the merits of low switching frequency and perfect harmonic performance. But less controllability and poor regulation lead the restriction on its application. A bidirectional pulsewidth modulation (PWM) converter based on multipulse structure is proposed in this paper, which has the same perfect harmonic performance with very low switching frequency. A special sequential sampling space vector modulation technique, which has the sampling sequence from the lagging module to the leading module, is proposed to make the converter controllable like conventional PWM converters. The harmonic performance and linear regulation capability are analyzed theoretically. The converter is modeled in detail, and an instantaneous feedback control strategy with phase delay compensation and decoupling control is also proposed. The controller parameters are optimized to get high dynamic performance with adequate phase margin and gain margin. A 3-kVA prototype is built, and the simulation and experiment results validate that the proposed converter is quite suitable for high-power conversion. 相似文献
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介绍了双环电流型脉宽调制(PWM)控制器UC3842的工作原理、特点以及使用中的功率因数校正和斜坡补偿方法.双环电流型PWM控制器是在普通电压反馈PWM控制环内部增加了电流反馈的控制环节,因而除了包含电压型PWM控制器的功能外,还能检测开关电流或电感电流,实现电压电流的双环控制. 相似文献
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新型高性能开关电源电压型PWM比较器 总被引:2,自引:0,他引:2
设计并实现了一种高性能的电压型PWM比较器,电路采用PMOS差分对管做为输入,多路电流镜提供精密负载电流,具有输入失调电压低、工作频率高、转换速率快和功耗低等优点.该电路可以替代普通电压型PWM比较器,直接运用在开关电源电压型PWM控制芯片中,并且能模块化设计,提高了PWM控制芯片的系统集成. 相似文献
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Ying-Yu Tzou Shiu-Yung Lin 《Industrial Electronics, IEEE Transactions on》1998,45(5):782-791
This paper proposes a new discrete fuzzy-tuning current-vector control (FTC) scheme for three-phase pulsewidth modulation (PWM) inverters. The proposed current control scheme can achieve fast transient responses and, at the same time, have very low total harmonic distortion in output current during steady-state operation. The proposed FTC scheme generates quasi-optimum PWM patterns by using a closed-loop control technique with instantaneous current feedback. The proposed FTC scheme has been realized using a single-chip digital signal processor (TMS320C14) from Texas Instruments. Experimental results are given to verify the proposed fuzzy-tuning current control strategy for three-phase PWM inverters 相似文献
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A single-phase controlled-current PWM rectifier 总被引:9,自引:0,他引:9
The analysis and test results are given for an experimental single-phase controlled-current PWM (pulse-width-modulated) rectifier that operates at unity power factor with near sinusoidal current waveform and that has power reversal capability. The twice-line-frequency AC power is identified as a source of voltage harmonics in the DC link. The harmonics enter into the voltage regulation feedback loop to distort the AC current waveform. These undesirable harmonics can be removed by a low-pass filter. It is noted that the overall design must address the possibility of instability due to the low-pass filter in the feedback path 相似文献
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Dancy A.P. Amirtharajah R. Chandrakasan A.P. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2000,8(3):252-263
This versatile power converter controller provides dual outputs at a fixed switching frequency and can regulate either output voltage or target system delay (using an external L-C filter). In the voltage regulation mode, the output voltage is monitored with an analog-digital (A/D) converter, and the feedback compensation network is implemented digitally. The generation of the pulsewidth modulation (PWM) signal is done with a hybrid delay line/counter approach, which saves power and area relative to previous implementations. Power devices are included on chip to create the two independently regulated output PWM signals. The key features of this design are its low-power dissipation, reconfigurability, use of either delay or voltage feedback, and multiple outputs 相似文献
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Xiaofen Shi Chok-You Chan 《Power Electronics, IEEE Transactions on》2002,17(5):633-640
A zero-voltage-transition pulse-width modulation (ZVT-PWM) converter composed of a conventional PWM circuit and a resonant tank to achieve zero-voltage switching, resulting in low voltage and current stresses and zero capacitive turn-on losses. In this paper, the analysis and passivity-based control of the ZVT-PWM buck converter are presented. A generalized state space average model of the ZVT-PWM buck converter is derived. The controller design is carried out using the derived model and follows the "energy shaping plus damping injection" ideas of the passivity-based approach. Both direct and indirect output voltage regulation schemes are addressed. Simulation results are presented to illustrate the features of the proposed controllers. 相似文献
19.
New inverter output filter topology for PWM motor drives 总被引:10,自引:0,他引:10
This paper presents a new inverter output filter topology for pulse width modulation (PWM) motor drives. It is shown that the proposed filter effectively reduces high frequency harmonics which can cause serious damage to the motor bearings and insulation. The proposed filter is comprised of a conventional resistance, inductance, capacitance (RLC) network cascaded with an LC trap filter. The LC trap, tuned to the inverter switching frequency, is very effective in reducing the switching harmonics. By using this new topology the need for high damping resistance and low RLC cut-off frequency is eliminated. This reduces the phase shift in the current regulation loop and increases the filter efficiency. Experimental verification of the filter topology is provided with a 180 V inverter and a 25 hp permanent magnet synchronous motor. Space-vector predictive current regulation is implemented as an inner-loop current regulator for the outer-loop speed control using a digital signal processor. The effectiveness of the filter at different motor speeds is presented 相似文献
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This paper describes a delay-and-addition cell that enables direct signal processing of pulse with modulation (PWM) encoded signals. The cell can be considered functionally equivalent to a switched capacitor integrator. However, both its input and output are synchronous PWM signals. As a difference to a switched capacitor integrator, the circuit does not require operational amplifiers and is composed of passive RC circuits, switches, comparators and digital logic. Circuit implementation non idealities such as offset and propagation delays have also been analyzed. The main advantage of this circuit is the possibility to operate at a low voltage. The paper shows measurements of a demonstration circuit implementing a first order filter. As an application example, the filter is used to attenuate the quantization noise of a sigma-delta signal, delivering a continuously varying PWM waveform from a synchronous bitstream. 相似文献