A study on the diagnostic and fail-safe of the PMSM

A motor fault must be detected immediately and fault tolerant control is used to significantly reduce the effects from the fault. In this paper, four types of fault are defined and the varied fault tolerant control methods are discussed. Herein, faults are classified in four types: encoder, DC link voltage, DC link current, and phase current. In the case of encoder faults, the hall signal can be used to estimate the rotor position. Fault tolerant control using the defined voltage is performed for a DC link voltage fault. When the DC link current provides a malicious value, the fault tolerant control uses the DC link current, converted from the phase current, and the motor performs in limited mode. Because the phase current has the same RMS and frequency, and a phase difference in a certain place, the difference in the current signal is used to detect the fault. When phase current fault happens, fault tolerant control is performed using the other phase current signals. As a result of this work, the defined fault types could be immediately detected and the fault tolerant control performed without any problems.1

A study on the speed control of a BLAC motor by feedforward compensation of the back-EMF using a fuzzy algorithm

Back electromotive force (back-EMF) feedforward compensation is used to improve the control performance of a brushless AC (BLAC) motor. The back-EMF has a speed component, and the response is slow when the back-EMF is compensated for by the speed. The back-EMF feedforward compensation does not operate exactly when the speed fluctuation is severe. To solve these problems, the back-EMF is compensated by the speed of the motor operation, which is calculated by the proposed method. The speed and the delta speed are the input membership functions of the fuzzy system. The weighting used to estimate the speed is defined as the output membership function of the fuzzy system. The speed is estimated exactly using 15 rules of the fuzzy system, and the back-EMF feedforward compensation operates using the estimated speed. The membership function and the fuzzy rules are adjusted using simulation. The root-mean-square (RMS) value of the error between the real speed and the reference speed is measured. It is confirmed that the performance is excellent when the back-EMF is compensated by the speed, which is estimated by the proposed algorithm. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.1

Design and Implementation of an EPB Diagnostic

The parking brake system fulfills a vehicle’s parking function. The EPB system uses a motor that requires a self-diagnostic function for reliability. Reliability of the EPB is ensured by monitoring the status of the electric module and motor. This paper describes an EPB that consists of hardware to perform self-diagnostics after defining the DTC. The reliability of software is improved by autocode generating source code using variable tools. As the size of DTC increases, it accordingly becomes more complex. The EPB therefore uses a multiplexer because it requires many A/D ports. The EPB defines 23 DTC. The selfdiagnostic function performs well and detects errors when the EPB checks the performance depending on the test conditions.1

EMB Position Contyrol Using a PI Gain Scheduling Method

A brake system is a nonlinear system which applies different compressive force depending on the position of the brake pad. The EMB(electric mechanical brake) used in passenger vehicles cannot detect the compressive force without a sensor. Therefore, it has different operating times at the same distance because the brake caliper applies different force depending on the position of the brake pad. A position controller for the EMB system was developed to control the operating time robustly at the same distance. A vector control method was used to operate the motor. The result of the position controller was used as the Q axis reference for the vector control method. The PI gain of the position was defined differently to meet the same operating time of the motor on each sector. In addition, the interval value between each position was calculated using an interpolation method. A PI gain of the position controller was tuned using the MATLAB tool, and the reliability of the position controller was verified through a simulation in the MATLAB. The verified PI controller was installed in an EMB system. The operating times were measured on each sector, showing that they were nearly identical. The proposed PI scheduling method was confirmed to have robust characteristics in a nonlinear EMB system with different amounts of compressive force depending on the position of the brake pad.1

Design and Implementation of a Fault Diagnosis and Fail safe on an Electronic Parking System

This paper is intended to present the design and implementation of a fault diagnostic and fail safe for an electronic parking brake system. The fault diagnostic function includes an input signal, output signal, and fault diagnostic using a microprocessor. The fault diagnostic function determines faults in the main microprocessor. The EPB has the function of the microprocessor and the permissible range of system control. The input signal detects faults using the voltage of the switch pole, the output signal defines faults using the current level of the motor. The microprocessor judges failure using internal software. And a sub microprocessor monitors the status of the main microprocessor using periodic communication between the main microprocessor and the sub microprocessor. Also, the microprocessor controls the output signal when emergencies occur. When the sub microprocessor judges that the main microprocessor and the system recovers from the fault. The safety and reliability of the EPB system can be improved using the proposed fault diagnosis system.1

Rotor Position Estimation of Permanent Magnet Synchronous Motors Using Low-Resolution Sensors

A fault diagnosis algorithm, which is necessary for constructing a reliable power conversion system, should detect fault occurrences as soon as possible to protect the entire system from fatal damages resulting from system malfunction. In this paper, a fault diagnosis algorithm is proposed to detect open- and short-circuit faults that occur in a boost converter switch. The inductor voltage is abnormally kept at a positive DC value during a short-circuit fault in the switch or at a negative DC value during an open-circuit fault condition until the inductor current becomes zero. By employing these abnormal properties during faulty conditions, the inductor voltage is compared with the switching function to detect each fault type by generating fault alarms when a fault occurs. As a result, from the fault alarm, a decision is made in response to the fault occurrence and the fault type in less than two switching time periods using the proposed algorithm constructed in analogue circuits. In addition, the proposed algorithm has good resistivity to discontinuous current-mode operation. As a result, this algorithm features the advantages of low cost and simplicity because of its simple analogue circuit configuration. © 2014 © 2014 Taylor & Francis.1

Study on Load Sensing Method by Speed of PMSM

The PMSM is widely used in industry. In order to detect faults and to monitor the system, it is important to detect changes in load for systems in which the PMSM is installed.However, the price of sensors is high and it is difficult to install sensors because of space limitations. Therefore, a method is proposed to detect the load using the speed of the motor in a system without sensors. An FOC method for operating the motor and a detection method using speed fluctuation have been studied; however, the speed includes many error components such as motor inertia and measurement error. To improve the accuracy of the speed measurement, the pulse count method has been studied and implemented. Actual experiments were performed to verify the proposed algorithm. The proposed algorithm detects the load variation at approximately the same time as the actual load is applied.1

A Study on the Speed Control of a Blac Motor by Back-Emf Feedforward Compensation

A PI controller is used to control the speed of a motor, but the gain of the PI controller is limited according to the system. Thus, the PI controller alone cannot meet the control performance requirements of the motor. A method involving back-electromotive force (back-EMF) compensation can solve this problem. Here, a feedforward compensation method based on the speed is used to compensate for the back-EMF. However, it is difficult to measure speed in the extremely low speed range, so it is difficult to compensate the back-EMF. In addition, the rate of the back-EMF compensation is modified by adjusting the gain. This proposed method of the back-EMF compensation is proven by simulation and experiment. The root mean square (RMS) value for the speed error is measured when the back-EMF is compensated for, when the back-EMF is not compensated for and when the gain of the back-EMF compensation is adjusted. The study confirms that the proposed algorithm is superior in the RMS value of the speed error.1

Design and Implementation for the Electronic Parking Brake System Based on Operating System

Electronic Parking Brake(EPB) system is operated by Electronic Control unit(ECU). EPB system has been by replaced a traditional parking brake system, which is a mechanical device to be driven by a parking brake lever or foot pedal. EPB system is more convenient for the women and elderly. Interior design as well as space utilization has also been important recently. By using EPB system, it is possible to ensure more space in a vehicle. Also, EPB system provides better convenience and safety than the traditional system through the cooperative control of Electric Stability Program(ESP) or alone. In this paper, we propose methodology of software architecture design and function development for the EPB system based on software tools.1