Yong-Kai Lin

Dead-Time Elimination of PWM-Controlled Inverter/Converter Without Separate Power Sources for Current Polarity Detection Circuit

This paper will present a dead-time elimination scheme for a pulsewidth-modulation (PWM)-controlled inverter/converter. The presented dead-time elimination scheme does not require separated power supplies for freewheeling-current detection of high- and low-side power devices. The presented scheme includes the freewheeling-current polarity detection circuit and the PWM control generator without dead time. It will be shown that the presented scheme eliminates the dead time of PWM control for inverter/converter and therefore dramatically improves output voltage loss and current distortion. Experimental results derived from a field-programmable-gate-array-based PWM-controlled inverter are shown to demonstrate the effectiveness.

A Unified Approach to Zero-Crossing Point Detection of Back EMF for Brushless DC Motor Drives without Current and Hall Sensors

The main theme of this paper is to present a unified approach to back electromotive force (EMF) detection of brushless dc motor (BLDCM) drives without using any current and Hall sensors. Pulsewidth modulation (PWM) techniques and theoretical analysis of back EMF detection are presented, and followed by the proposed unified back EMF detection method. It will be shown that the back EMF detection depends upon the PWM techniques and the method is required to be slightly modified as the PWM technique is changed. Experimental results derived from BLDCM drives without using any current and Hall sensors fully confirm the theoretical analysis.

Pulsewidth Modulation Technique for BLDCM Drives to Reduce Commutation Torque Ripple Without Calculation of Commutation Time

This paper presents a three-phase pulsewidth modulation (PWM) technique for brushless dc motor (BLDCM) drives to reduce the commutation torque ripple. As compared to previous approaches, the presented technique does not require any torque observer and calculation of commutation time which may be sensitive to motor parameters and may require more calculation time. The commutation time for the presented technique is determined by a detection circuit which consists of simple comparator circuit. The experimental results derived from a field programmable gate array based controlled BLDCM drive show that the commutation current ripple can be significantly reduced by the presented PWM technique.

New Hybrid Pulsewidth Modulation Technique to Reduce Current Distortion and Extend Current Reconstruction Range for a Three-Phase Inverter Using Only DC-link Sensor

This paper proposes a new modulation technique that can reduce the current distortion and extend the current reconstruction range for a three-phase inverter using only dc-link sensor. The proposed pulsewidth modulation (PWM) technique is a hybrid method which consists of space vector modulation method and the PWM method without using null switching states. The former provides low current distortion; however, it is with narrower current reconstruction range. In contrast, the latter extends the current reconstruction range at the cost of higher current distortion. For the proposed method, in the measurable region of space vector modulation method, space vector modulation is used to reduce the current distortion. Moreover, as the modulation range is out of the measurable region, the PWM method without using null switching states is applied to extend the current reconstruction range. Furthermore, the current reconstruction limitation using only dc-link sensor is analyzed. The analysis shows that the reduction of PWM switching frequency and acquisition time can extend the current reconstruction range. Comparison of experimental results derived from a field-programmable gate array-based controlled inverter is included. It will be demonstrated that using the proposed hybrid PWM technique, the three-phase current signals of the inverter can be reconstructed even under very low modulation index range while providing low current harmonic distortion of inverter output.

Novel Back-EMF Detection Technique of Brushless DC Motor Drives for Wide Range Control Without Using Current and Position Sensors

This paper presents a new back-electromotive force (EMF) detection technique which provides wide range control for brushless dc motor (BLDCM) drives. As compared with previous techniques which can be used either for low duty-ratio control or for high duty-ratio control only, the proposed technique deals with the above-mentioned problem to give both low and high duty-ratio control while not invoking any position and current sensors. The zero crossing point of back-EMF which is used for generating proper commutation control of inverter is calculated by sampling the voltage of floating phase. Therefore, no current and position sensors are required for the implementation. The presented method can be easily implemented using digital controller. An field programmable gate array-based BLDCM driver system is set up to demonstrate that the presented technique works well from standstill to rated speed.

Integrated Inverter/Converter Circuit and Control Technique of Motor Drives With Dual-Mode Control for EV/HEV Applications

A new integrated circuit for motor drives with dual-mode control for EV/HEV applications is proposed. The proposed integrated circuit allows the permanent magnet synchronous motor to operate in motor mode or acts as boost inductors of the boost converter, and thereby boosting the output torque coupled to the same transmission system or dc-link voltage of the inverter connected to the output of the integrated circuit. In motor mode, the proposed integrated circuit acts as an inverter and it becomes a boost-type boost converter, while using the motor windings as the boost inductors to boost the converter output voltage. Moreover, a new control technique for the proposed integrated circuit under boost converter mode is proposed to increase the efficiency. The proposed control technique is to use interleaved control to significantly reduce the current ripple and thereby reducing the losses and thermal stress under heavy-load condition. In contrast, single-phase control is used for not invoking additional switching and conduction losses under light-load condition. Experimental results derived from digital-controlled 3-kW inverter/converter using digital signal processing show the voltage boost ratio can go up to 600 W to 3 kW. And the efficiency is 93.83% under full-load condition while keeping the motor temperature at the atmosphere level. These results fully confirm the claimed merits for the proposed integrated circuit.

Assessment of Pulse-Width Modulation Techniques for Brushless DC Motor Drives

The purpose of this paper is to assess the pulse-width modulation (PWM) techniques for brushless DC motor (BLDCM) motor drives. The criteria for assessment include driver circuit, reversal DC-link current, circulating current of floating phase, and back electro-magnetic force (EMF) detection. The advantages and disadvantages of five PWM techniques for BLDCM drives will be analyzed and confirmed by experimental results. The results presented in this paper are expected to provide whole picture for applications reference

Dead-time elimination of pwm-controlled inverter/converter without separate power sources for current polarity detection circuit

This paper will present a dead-time elimination scheme for PWM-controlled inverter/converter. The presented dead-time elimination scheme doesnpsilat require separated power supplies for wheeling current detection of high-side and low-side power devices. The presented scheme includes the freewheeling current polarity detection circuit and the PWM control generator without dead-time. It will be shown that the presented scheme eliminates the dead-time of PWM control for inverter/converter and therefore dramatically improving the output voltage loss and current distortion. Experimental results derived from an FPGA-based PWM-controlled inverter are shown to demonstrate the effectiveness.

Back-EMF Detection Technique of Brushless DC Motor Drives for Wide Range Control

This paper presents a new back-EMF detection technique which provides wide range control for brushless DC motor (BLDCM) drives. As compared with previous techniques which can be used either for low duty-ratio control or for high duty-ratio control only, the proposed technique deals with the above-mentioned problem to give both low and high duty-ratio control while not invoking any position and current sensors. The zero crossing point of back-EMF which is used for generating proper commutation control of inverter is calculated by sampling the voltage of floating phase. The presented method can be easily implemented using digital controller. An FPGA-based BLDCM driver system is set up to demonstrate that the presented technique works well from standstill to rated speed

Dead-time elimination method and current polarity detection circuit for three-phase PWM-controlled inverter

This paper will present a dead-time elimination scheme and the related current polarity detection circuit without separate power sources for three-phase inverters. The presented scheme includes the freewheeling current polarity detection circuit and the PWM control generator without dead time. It will be shown that the presented scheme eliminates the dead time of PWM control for inverter and therefore dramatically improving the output voltage loss and current distortion. Experimental results derived from an FPGA-based PWM-controlled inverter are shown for confirmation.