Browsing by Author "Tzou, Ying-Yu"

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A new sensorless starting method for brushless DC motors without reversing rotation
(2007)
Chang, Yen-Chuan
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Tzou, Ying-Yu
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents a new sensorless starting method for brushless DC motors without reversing rotation for unidirectional applications. The method can detect the rotor position at standstill and a specific start-up method is then used to accelerate the motor up to a middle-speed where conventional sensorless control algorithms based on the back-EMF can work properly. The proposed scheme employs only one current sensor at DC-link side of the inverter, and can be applied to a motor without knowing its parameters and additional position sensors. As compared with previous approaches, the presented technique can simplify the sensorless position detection procedure and lower the cost. The proposed initial rotor position detection technique has a resolution of 30 electrical degrees, and does not cause any rotor vibration during the detection process. The sensorless starting scheme has been implemented on a single-chip DSP controller (TMS320LF2407A) and experimental results reveal that the starting procedure can work smoothly without temporarily reversing rotation.
Adaptive Soft Starting Method with Current Limit Strategy for Sensorless BLDC Motors
(2012)
Kan, Kai-Sheng
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Tzou, Ying-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
This paper proposes an adaptive soft start-up strategy for sensorless control of three-phase BLDC motors in applications to consumer electronics and high efficiency cooling fans. The proposed start-up control scheme combines a closed-loop I/ Hz control with adaptive ramping current profile in accordance to different load torque-speed characteristic. The proposed start-up scheme can reduce the start-up current while at the same time provides a robust and smooth start-up for different applications. A synchronous current sampling control scheme based on the dc-link current is developed for the regulation of motor phase current. A start-up current limit profile is calculated based on assumed load torque-speed characteristics. The controller will switch to sensorless control mode once a verified sensorless commutation signal is detected. Simulation and experimental results have been given to show the robustness of the proposed sensorless start-up control scheme.
Adaptive Wide Angle PWM Control Strategy of BLDC Motor Drive for Efficiency Optimization and Wide Speed Control Range
(2011)
Kan, Kai Sheng
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Tzou, Ying-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
To reduce the torque pulsation of BLDC motors caused by conventional 120 degrees commutation conduction control, this paper proposes an adaptive wide angle control scheme with adjustable modulation waveform to achieve wide speed control range with efficiency optimization. The proposed adaptive soft commutation PWM modulation scheme is based on an adjustable modulation waveform with wide angle conduction period (more than 120 degrees but less than 180 degrees) and control the phase current with quasi-sinusoidal waveform to minimize the pulsation torque due to commutation. By using the adaptive PWM modulation scheme, the RMS value of phase current is lower than conventional 120 degrees conduction mode under the same testing condition. Compared with the traditional control method, torque ripple of the BLDC motor can be reduced significantly by using the proposed control method. Simulation and experimental verification have been given to illustrate the performance of the proposed PWM strategy.
An Innovative Multiphase PWM Control Strategy for a PMSM with Segmented Stator Windings
(2015)
Lin, Chiao-Chien
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Tzou, Ying-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
This paper proposes a multiphase converter topology with an innovative PWM strategy for the control of a PM synchronous motor with segmented stator windings to operate as an electronic geared motor. Simulation studies of the segmented PMSM with configurable stator windings have been carried out. Compared with conventional three-phase inverter topology, the proposed converter topology with associated PWM modulation strategy has advantages of reduced conduction loss, improved efficiency under light load condition, and expanded torque-speed operating ranges with a same dc-link voltage. The interleaved PWM strategy provides advantages of ripple current reduction and conduction losses reduction. Simulation results have been given to show advantages and flexibility of the proposed multi-phase PWM control scheme for a PMSM with segmented windings.
Architecture implementation of class-D amplifiers using digital-controlled multiphase-interleaved PWM technique
(2006)
Lin, Yu-Tzung
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Lee, Chi-Yang
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Tzou, Ying-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
The class-D amplifier has the advantages of having a high efficiency, a small-size and gains its wide applications in battery-powered audio systems. However, its output power is limited by the rating of its output transistors. This paper presents the development of a new architecture for the realization of a class-D audio amplifier using a digital-controlled multi-phase interleaved PWM converter to enhance its output power. This interleaved technique is widely used in DC-DC converters. A digital current control technique with interleaved PWM generation was developed to reduce the total harmonic distortion (THD) of the output current under lower PWM switching frequency. A comparative evaluation of a single-phase and a three-phase class-D amplifier structure is presented. Furthermore, the design and implementation of a digital control IC, including an ADC synchronous sampler, a digital compensator, and a phase-shift PWM generator, is introduced. Computer simulations and experimental verifications are given to illustrate the feasibility and performance of the proposed technique.
Calculation of Losses and Temperature Rise for High Frequency Transformer under Forced-air Convection
(2010)
Chang, Ren-Chun
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Chen, Chien-Kuo
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Wang, Chien-Yue
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Tzou, Ying-Yu
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電機工程學系
This paper presents a method for loss calculation, including core losses and winding losses, and temperature rise in high frequency transformer design under forced-air convection. Analytical models of winding losses for multiple-layer copper foil and Litz wire windings with MMF boundary conditions have been developed. Geometric parameters of conductor and distribution of magneto-motive forces are considered in the formulation of the winding loss equations. Comparing with the FEM simulation result, it shows that these two models can achieve good accuracy. The core losses were calculated using modified Steinmetz equation (MSE), which has been validated for power ferrite material. The winding loss models, including copper foil model and Litz wire model, were developed for multiple-layer with magneto-motive forces boundary conditions. To verify the accuracy of these two models, the 2D FEM simulation was used for comparison, and the errors of copper foil model and Litz wire model were within 1% and around 5%similar to 9%, respectively. The 5-R modified model for E-type core was presented as 5 resistors by thermal network to evaluate temperature rise under forced-air convection, and the heat transfer coefficients and material properties were obtained using thermal measurement in wind tunnel.
Control of a Single-phase Grid Inverter with On-line Inductance Identification
(2016)
Liu, Shih-Chun
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Wu, Kao-Chih
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Tzou, Ying-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
This paper proposes a novel on-line inductance identification method to account for inductance saturation in current controller design for single-phase grid-connected inverter with single inductor filter. The predictive control method with delay compensation is used which has wide bandwidth and reaches steady state within one switching period in current control loop. A multiple-sampling method is developed for instantaneous current feedback, which can get average current even in DCM operation and low duty ratio conditions. An on-line inductance identification technique is proposed to compensate the model inductance parameter variation and stabilize the transient disturbances. Simulation and experiment results have been carried out to verify the results.
Design and implementation of a voice-coil motor servo control IC for auto-focus mobile camera applications
(2007)
Hsu, Jhih-Da
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Tsai, Ching-Lung
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Tzou, Ying-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents the design methodology to implement a fully digital control IC for the position control of the auto-focus (AF) lens module in applications to mobile phone camera using the field programmable gate array (FPGA). As compared with the conventional stepping motor control with a spring return fixture, the AF lens module is driven by a voice-coil motor (VCM) with a digital servo drive IC. The proposed digital servo drive IC includes a digital servo controller, a digital current controller, and a full-bridge dc-dc converter. The designed digital servo drive IC provides a total digital solution to the position control of the AF lens module in applications to high-performance light-weight slim-type mobile phone camera and video. The designed AF lens module can reach a control range of 0.6 mm within 30 ms with a control resolution less than 5 mu m, a peak driving force of 30 mN, and a peak output current of 120 mA.
Design and realization of a digital multiphase-interleaved VRM controller using FPGA
(2007)
Wang, Yi-Chung
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Tzou, Ying-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
Voltage Regulator Modules (VRM) are used for low-voltage, high-current dc-dc converters used for high-performance microprocessors and graphic processors. This paper describes the development of a digital PWM controller architecture in applications to multiphase-interleaved VRM. A digital current control technique with interleaved PWM generation and synchronous current sampling has been developed to improve the transient response under large load disturbances. The proposed control scheme for the interleaved multiphase buck converter employs feedback signals of output voltage, output current, and per-phase inductor current. By using a synchronous over-sampling, technique for the detection per-phase inductor current and double-edge PWM modulation technique, the current response can reach a deadbeat performance for step current command. Current sharing control is used to equalize the current of each phase converter under possible parameters mismatch. A computer simulation study has been carried out to illustrate the feasibility and performance of the proposed digital control technique.
Design of a digital servo control IC for permanent magnet synchronous motors with linear hall sensors
(2007)
Chang, Yen-Chuan
;
Tzou, Ying-Yu
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents the design and architecture implementation of a digital position control IC for permanent magnet synchronous motors (PMSMs) with sinusoidal flux distribution using linear Hall sensors for low-cost motion control applications. The absolute rotor position is calculated from the measured Hall sensor signals and a speed estimator is devised to generate speed feedback for the servo loop compensator. The developed digital servo control IC for PMSM motors with linear Hall sensors consists of three major control blocks: a servo loop controller, a position and speed estimator, and a field-oriented torque controller. The accuracy of positioning control resolution can be improved by a position error compensation table via external position calibration. All the control blocks are realized by using digital circuitry with configurable and reusable intellecture property (IP) blocks. Experiment results are presented to verify the performance and feasibility of the proposed IC.
Development of a Mixed-Signal PFC Control IC with Fast Dynamic Response
(2009)
Chan, Ming-Hau
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Lin, Yu-Tzung
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Tzou, Ying-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents a mixed-signal power-factor-correction (PFC) control IC for the single-phase critical-conduction-mode (CRM) boost AC/DC converters. The peak current mode control is used and realized by using the analog circuit technique. The outer voltage loop control adopts digital control technique to implement. This paper analyzes effect of the hysteresis band of the comparator in current loop is implemented by analog circuit. In digital voltage loop, this paper proposes usage of a digital notch filter to achieve fast dynamic response under large step load variations while maintaining a low total-harmonic-distortion (THD) and a high power factor (PF). The proposed mixed-signal PFC control scheme has been verified by using computer simulation via PSIM and Simplis to validate feasibility.
Digital Control of a Bridgeless SEPIC PFC AC-DC Converter with Variable Voltage Output
(2015)
Ho, Kuan-Sheng
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Wu, Kao-Chih
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Tzou, Ying-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
Instead of constant dc-link voltage, this paper proposes a PAM/PWM for PMSM drive, which provides variable dc-link voltage to PWM inverter to reduce switching loss and improve system efficiency. An optimal dc-link voltage reference can be found for a specified operation speed for a centrifugal load condition. In order to realize the variable dc-link voltage, this paper implements a variable output voltage power factor correction (VOPFC) AC-DC converter for PMSM drive with bridgeless single ended primary inductor converter (SEPIC) topology. When it operates in DCM mode input current is in-phase with input voltage automatically and yields unit power factor. Therefore current control loop can be omitted and control system is simplified. Simulation and experimental results have been carried out to verify the performance of the PFC converter.
Digital control of a multi-phase interleaved PWM inverter with minimal total harmonic distortion
(2007)
Lin, Yu-Tzung
;
Tzou, Ying-Yu
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents a digital repetitive control scheme for the minimization of output voltage total harmonic distortion (THD) of a PWM inverter under large unknown nonlinear load. The multi-phase interleaved PWM inverter has been adopted to enhance the effective switching frequency as well as to share the load current. The realization of a digital control for PWM inverter, such as sampling delay and quantization error, may introduce many nonlinear effects to distort its output waveforms. A systematic design procedure is developed to minimize selected range of harmonic spectrum by shaping the output impedance by so that its output voltage THD can be lower than a specified value with given design constraints. The proposed control scheme has been realized with fully digital design by using a single-chip FPGA implementation and verified by using co-simulation technique via a VHDL simulator Modelsim combined with a system-level block diagram oriented simulator Simulink.
Digital Control Strategy for Efficiency Optimization of a BLDC Motor Driver with VOPFC
(2009)
Wu, Chia-Hao
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Tzou, Ying-Yu
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電機工程學系
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Department of Electrical and Computer Engineering
This paper proposes a dual-mode control strategy for BLDC motor drivers with power factor correction used in high-efficiency compressor applications. The motor driver consists of a front-stage variable output voltage PFC (VOPFC) converter and a rear-stage 3-phase PWM inverter. The VOPFC converter is a cascaded buck-boost converter with two power switches to regulate the input line current with low total harmonic distortion (THD) and at the same time to maintain an adjustable dc-link voltage which can be either higher or lower than the peak of the rectified line voltage. The output inverter stage can be operated in pulse amplitude modulation (PAM) mode or PWM mode with reduced switching frequency for efficiency optimization of the compressor motor driver to maintain a constant V/Hz ratio with specified current ripples. The proposed control scheme has been verified with a DSP-controlled VOPFC PWM/PAM motor driver and an efficiency improvement of 3% has been achieved.
Digital Primary-Side Sensing and PFC Control of a Flyback Converter
(2011)
Lin, Chih-Wei
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Tzou, Ying-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
Primary-side sensing (PSS) technique can be used for the output voltage or current regulation of a flyback converter by employing an auxiliary winding for the indirect detection of output voltage and conduction period of the output rectifier diode. However, errors in the estimation of output voltage or current may be induced by the voltage drop of the secondary diode, secondary leakage inductance, secondary winding resistance, and measurement error due to limited bandwidth of the sensing circuits. In this paper, a sampling instant modulation technique is developed to reduce the sensing error in primary-side sensing of flyback converters. This new PSS sampling technique is then implemented for the power factor correction (PFC) of a flyback converter. A multi-mode control strategy can improve sampling accuracy at the zero-crossing of the rectified input voltage. Experimental results are shown to verify the feasibility of PSS technique realized with digital control technique.
Digital Primary-Side Sensing Control for Flyback Converters
(2009)
Chang, Che-Wei
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Lin, Yu-Tzung
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Tzou, Ying-Yu
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電機工程學系
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Department of Electrical and Computer Engineering
Primary-side sensing (PSS) technique can be used for the output voltage or current regulation by employing an auxiliary winding. However, the sensed voltage may be corrupted by switching noise due to leakage inductance, winding resistance, and nonlinearity of the magnetic core, therefore the sensed voltage can only achieve limited accuracy. With the advance of power control IC realization technology, more complicated control and estimation algorithms can be realized by using analog, digital, or mixed-signal technologies. This paper introduces a digital control method to make the influence of nonideal factors as low as possible. A key factor for accurate voltage sensing is the determination of sampling instant on the auxiliary winding. A prototype of a DCM DC/DC flyback converter with digital signal processor has been realized to verify the proposed digital PSS scheme.
Digital Voltage Control of Boost CRM PFC AC/DC Converters with TRIAC Phase Control Dimmer
(2012)
Lin, Chih-Wei
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Tzou, Ying-Yu
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電機工程學系
;
Department of Electrical and Computer Engineering
This paper presents a digital voltage control scheme for boost critical conduction mode (CRM) power-factor-correction (PFC) AC/DC converters with TRIAC phase control dimmer to use in the lighting equipment ex. LED or fluorescent lamp. The TRIAC is a standard type of dimmer and work fine with resistive load such as ordinary Tungsten filament light bulb (incandescent lamp), however, for non-resistive lighting sources, a well-designed AC-DC converter must be designed to provide good power quality as well as wide linear non-flickering dimming control range. A variable PFC output voltage modulation method is proposed to enhance the dimming control range. The TRIAC dimmer will cause switching oscillations due to the PFC input filter, a damper circuit is designed to minimize this effect. The proposed control scheme has been verified by using simulation software PSIM in applications to a 50 W prototype of boost CRM PFC AC/DC converter with TRIAC phase control dimmer. Simulation and experimental results are given to illustrate the feasibility of the proposed control scheme.
Efficiency Optimization Control for Single-Phase Brushless DC Fan Motors
(2009)
Chen, Wei-Chao
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Tzou, Ying-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
This paper proposes a modeling method for characterization of single-phase brushless dc (BLOC) fan motors in applications to information appliances. The nonlinear back-EMF induced by the rotor flux with stator winding is modeled by a look-up table. By parameter identification and computer simulation, this modeling method assists designers in waveform analysis and control loop design. Simulation results have been verified with the measured experimental results. Moreover, in order to improve the efficiency of the BLDC fan motor over the entire speed control range, this paper develops an efficiency optimization control method based on a closed-loop current control scheme by using the Hall sensor feedback. The proposed control scheme has been realized and compared with the conventional open-loop PWM control scheme. Experimental results show a 40% reduction of peak current and 18% reduction of RIMS current have been achieved at rotation speed of 3000 RPM.
FPGA Control and Implementation of a Multiphase-Interleaved PWM Inverter for a Segmented PMSM
(2015)
Hsu, Hsung-Hao
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Tzou, Ying-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
This paper proposes a digital PWM control technique for a segmented permanent magnet synchronous motor with multi-phase interleaved PWM inverters. A segmented motor with its segmented stator windings can be connected and excited by segmented PWM converters using multiphase interleaved PWM techniques. A phase shedding control strategy is developed for efficiency optimization when operating in light load condition. A digital PWM modulator with adjustable switching frequency and phase shift has been realized with FPGA. Analysis oriented simulation has been carried out for the loss analysis of the multiphase interleaved PWM inverter. Experimental verification has been carried out to show the improvement of the proposed digital PWM technique.
FPGA Control of a Single-Phase T-Type NPC Grid Inverter for Low THD and Robust Performance
(2017-01-01)
Kuo, Chin-Chang
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Tzou, Ying-Yu
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電控工程研究所
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Institute of Electrical and Control Engineering
This paper presents an FPGA-based adaptive predictive control scheme for single-phase T-type NPC inverter in applications to microgrids with high efficiency and robust performance. Predictive control is applied for current regulation to achieve fast dynamic response with low total harmonic distortion (THD). Implementation of a grid inverter with minimum inductor will result nonlinear inductance due to saturation effect. This nonlinearity can be tolerated with conventional PI controller with low bandwidth performance, however, oscillations or even instability may occur for predictive control with fast dynamic responses. An adaptive predictive control scheme with on-line inductance identification has been developed to ensure both fast dynamic response and robust stability. The proposed adaptive predictive controller has been realized using a mixed-signal FPGA Smartfusion (R) A2F500 from Microsemi. Experimental verification is carried out with a 3kW single-phase AT-NPC grid inverter. Experimental results show that the proposed control scheme can achieve both fast dynamic responses and high quality current regulation with THD close to its theoretical limits.