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Please note that Spansion will not be liable to you and/or any third party for any claims or damages arising in connection with above-mentioned uses of the products. Any semiconductor devices have an inherent chance of failure. You must protect against injury, damage or loss from such failures by incorporating safety design measures into your facility and equipment such as redundancy, fire protection, and prevention of over-current levels and other abnormal operating conditions. If any products described in this document represent goods or technologies subject to certain restrictions on export under the Foreign Exchange and Foreign Trade Law of Japan, the US Export Administration Regulations or the applicable laws of any other country, the prior authorization by the respective government entity will be required for export of those products. Trademarks and Notice The contents of this document are subject to change without notice. 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Application Note MCU-AN-510113-E-10 32-BIT MICROCONTROLLER ALL SERIES ELECTRICAL BRAKE APPLICATION ON BLDC WASHER APPLICATION NOTE ARM and Cortex-M3 are the trademarks of ARM Limited in the EU and other countries. Electrical Brake V1.0.0 Revision History Revision History Version Date Updated by 1.0.0 2012-02-29 Borg Zheng Approved by Modifications First Draft This manual contains 13 pages. Specifications are subject to change without notice. For further information please contact each office. All Rights Reserved. The contents of this document are subject to change without notice. Customers are advised to consult with sales representatives before ordering. The information, such as descriptions of function and application circuit examples, in this document are presented solely for the purpose of reference to show examples of operations and uses of FUJITSU SEMICONDUCTOR device; FUJITSU SEMICONDUCTOR does not warrant proper operation of the device with respect to use based on such information. When you develop equipment incorporating the device based on such information, you must assume any responsibility arising out of such use of the information. FUJITSU SEMICONDUCTOR assumes no liability for any damages whatsoever arising out of the use of the information. Any information in this document, including descriptions of function and schematic diagrams, shall not be construed as license of the use or exercise of any intellectual property right, such as patent right or copyright, or any other right of FUJITSU SEMICONDUCTOR or any third party or does FUJITSU SEMICONDUCTOR warrant non-infringement of any third-party's intellectual property right or other right by using such information. FUJITSU SEMICONDUCTOR assumes no liability for any infringement of the intellectual property rights or other rights of third parties which would result from the use of information contained herein. The products described in this document are designed, developed and manufactured as contemplated for general use, including without limitation, ordinary industrial use, general office use, personal use, and household use, but are not designed, developed and manufactured as contemplated (1) for use accompanying fatal risks or dangers that, unless extremely high safety is secured, could have a serious effect to the public, and could lead directly to death, personal injury, severe physical damage or other loss (i.e., nuclear reaction control in nuclear facility, aircraft flight control, air traffic control, mass transport control, medical life support system, missile launch control in weapon system), or (2) for use requiring extremely high reliability (i.e., submersible repeater and artificial satellite). Please note that FUJITSU SEMICONDUCTOR will not be liable against you and/or any third party for any claims or damages arising in connection with above-mentioned uses of the products. Any semiconductor devices have an inherent chance of failure. You must protect against injury, damage or loss from such failures by incorporating safety design measures into your facility and equipment such as redundancy, fire protection, and prevention of over-current levels and other abnormal operating conditions. Exportation/release of any products described in this document may require necessary procedures in accordance with the regulations of the Foreign Exchange and Foreign Trade Control Law of Japan and/or US export control laws. The company names and brand names herein are the trademarks or registered trademarks of their respective owners. Copyright © 2012 Fujitsu Semiconductor Design (Chengdu) Co. Ltd. All rights reserved. MCU-AN-510113-E-10 – Page 2 Electrical Brake V1.0.0 Contents Contents REVISION HISTORY ............................................................................................................ 2 CONTENTS .......................................................................................................................... 3 1 INTRODUCTION .............................................................................................................. 4 1.1 Purpose ................................................................................................................... 4 1.2 Definitions, Acronyms and Abbreviations ................................................................ 4 1.3 Document Overview ................................................................................................ 4 2 PRINCIPLES OF ELECTRICAL BRAKING ..................................................................... 5 2.1 SVPWM Principle .................................................... Error! Bookmark not defined. 2.2 Electrical Braking Principle ...................................................................................... 6 3 THE IMPLEMENTATION OF ELECTRICAL BRAKING................................................... 9 3.1 Feature.................................................................................................................... 9 3.2 Flowchart of Electrical Braking .............................................................................. 10 3.3 Waveform of Electrical Braking.............................................................................. 10 3.4 Conclusion ............................................................................................................ 12 4 APPENDIX ..................................................................................................................... 13 4.1 List of Figures and Tables ..................................................................................... 13 MCU-AN-510113-E-10 – Page 3 Electrical Brake V1.0.0 Chapter 1 Introduction 1 Introduction This document introduces the electrical brake solution on direct drive or belt drive washers. 1.1 Purpose In a great many systems, motors are stopped simply by natural deceleration, but the stop time may be long for the spin cycle of washers. The time often needs to be cut down and electrical braking is a simple and efficient solution. Compared to mechanical and hydraulic braking systems, it has the advantage of steadiness and does not require any wear parts. 1.2 Definitions, Acronyms and Abbreviations PMSM - Permanent Magnet Synchronous Motor BLDC - Brush Less DC Motor DD - Direct drive washer - DC bus voltage Vsq - Voltage on q axis of d/q coordinate in FOC algorithm Vsd - Voltage on d axis of d/q coordinate in FOC algorithm Isq - Current on q axis of d/q coordinate in FOC algorithm Isd - Current on d axis of d/q coordinate in FOC algorithm n - Rotor rotation speed - d-axis reference current - q-axis reference current - Max limit of current scalar - Max limit of voltage scalar - Flux link-age - Rotor electrical angular velocity 1.3 Document Overview The rest of document is organized as the following: Chapter 2 explains the principles of electrical braking. Chapter 3 explains the implementation of electrical braking. MCU-AN-510113-E-10 – Page 4 Electrical Brake V1.0.0 Chapter 2 Principles of Electrical Braking 2 Principles of Electrical Braking The stop time of spin cycle on washer may be above 1 minute If the motor is stopped by the electrical drives, which may be result introducing more the system mechanical noise. The electrical braking solution must be needed in washers due to the cost and system requirement. There are several solutions for electrical braking such as plug braking, regenerative braking and dynamic braking. Dynamic braking The back-EMF is consumed on the resistor which is between the DC bus. Regenerative braking If the back-EMF of the motor is higher than the DC voltage inputted, Regenerative braking sends the regenerated energy from the motor back through the DC-silicon-controlled rectifier (SCR) converter. Plugging braking Swith on all of the lower bridge directly, this method has the best braking effect and the shortest stop time. But the braking current is the biggest in this solution. No braking resistor is required in this case and the hardware design of the power circuit can be significantly simplified. The plug braking is adopted on the washer solution of Fujitsu. And the back-EMF energy can be dissipated in the motor windings. How to reduce the current overshoot at the start of electrical brake has been focused and solved. 2.1 SVPWM Principle The space vector modulation is used to generate the voltages applied to the stator phases. It uses a special scheme to switch the power transistors to generate sinusoidal currents in the stator phases. Figure 2-1 shows the simplified structure of driving hardware which is used to generate the SVPWM signal. U V W Motor ia ib ic Figure 2-1: Simplified Structure of Driving Hardware MCU-AN-510113-E-10 – Page 5 Electrical Brake V1.0.0 Chapter 2 Principles of Electrical Braking V2 V6 cw 1° 5° V3 3° 4° 6° V4 2° V1 V5 Start Vector End Vector Figure 2-2: SVPWM Sector Rotation for CW The SVPWM sector and how to generate the SVPWM are shown as Figure 2-2 and Figure 2-4. Take the ‘sector 4’ for example, the vector should be ‘001’ ‘011’ and ‘011’ ‘001’. 2.2 Electrical Braking Principle The Plugging braking will generate the phase current overshoot at the start of the brake. But this phase current over charge can be decreased by making use of the back-EMF feature of the BLDC. The back-EMF of the BLDC motor for CCW rotation is shown as Figure 2-3. The current overshoot is always caused by the back-EMF, if the back-EMF is not dissipated naturally in the motor windings, the electrical braking current might be overshoot above 17A. Figure 2-3: Relationship between Hall and back-EMF Relationship between SVPWM sector and hall sector is shown as Table 2-1 and Figure 2-4. Table 2-1: Hall Correction Theta Hall sector Electrical theta(deg) Electrical theta(deg) CW CCW 1 210 330 2 90 90 3 150 30 4 330 210 5 270 270 6 30 150 MCU-AN-510113-E-10 – Page 6 Electrical Brake V1.0.0 Chapter 2 Principles of Electrical Braking The hall correction sequence for Motor CW(drumb CCW) is 6 2 3 1 5 4, and on the other hand, The hall correction sequence for Motor CCW(drumb CW) is 3 2 6 4 5 1. Table 2-2: Table for SVPWM Switch Rule sector CW CCW UH:VH:WH WH:VH:UH V4 100 001 V6 110 011 V2 010 010 V3 011 110 V1 001 100 V5 101 101 V1 V5 CCW S6H6 V3 S4H2 S2H4 S5H3 S3H5 V4 S1H1 V2 V6 Start Vector End Vector Figure 2-4: Relationship between Hall and SVPWM Sector for Motor CCW When the BLDC belt drive washer is working on the spin stage, the motor rotates for CCW. And the introduction for electrical braking solution is basic on this motor rotation. The motor CCW rotation direction is corresponding to the CW rotation direction of belt drive BLDC washer. When the rotor position is between the hall sensor sector 6, the back-EMF of W phase is crossing zero as Figure 2-3. And the SVPWM is 6 this time which is shown as ‘S6H6’ in Table 2-1 and Figure 2-4, so the SVPWM vector is “001” ”101”. As shown in Table 2-2, the bridge ‘UH’ would no be changed and always ‘1’ in each SVPWM cycle, and bridge ‘VH’ may be changed in each SVPWM cycle which will lead the back-EMF changing on this phase. If the lower bridge of ‘UL’ is switch on, the chaning back-EMF of phase ‘W’ will disturb to other phases and the phase current may over shoot over 15A; so the lower bridge of ‘UL’ must be switched off and the chaning back-EMF of phase W can be dissipated naturally in the motor, the phase current may over shoot a little which may be smaller than 13A due to the phase W is crossing zero in this sector, that will ensure the reality of the inverter and motor. Figure 2-5 shows the switch sequence at the motor brake. Firstly, the UL switch on and the other bridge are switched off at the hall sector ‘6’ and ‘4’; secondly, The UL and WL switch on and the other bridge are switched off at the hall sector ‘5’ ; and the last is all of the three bridges switch on. MCU-AN-510113-E-10 – Page 7 Electrical Brake V1.0.0 Chapter 2 Principles of Electrical Braking UH VH WH U V W 3 1 2 UL VL ia ib WL Motor ic Figure 2-5: Lower Bridge Switching Sequence at Motor Brake MCU-AN-510113-E-10 – Page 8 Electrical Brake V1.0.0 Chapter 3 Implementation of Electrical Braking 3 Implementation of Electrical Braking The implementation of the electrical braking is introduced in the chapter, and the control block of the hall sensor washer solution is shown as Figure 3-1. Figure 3-1: PMSM Control Block with Hall Sensor Solution 3.1 Feature Phase current overshoot about 25% of the motor saturation current at the start of the electrical brake. No hardware cost with the electrical braking. The stop time decrease greatly by this electrical braking, and low resource occupancy for the FOC control. MCU-AN-510113-E-10 – Page 9 Electrical Brake V1.0.0 Chapter 3 Implementation of Electrical Braking 3.2 Flowchart of Electrical Braking FOC ISR start N Motor stop and ele brake enable Y Hall sector ==6 N Y UL switch on Hall sector ==5 N Y UL and WL switch on Hall sector ==1 Y All low bridge switch on FOC algorithm FOC ISR End Figure 3-2: Flowchart for Electrical Braking 3.3 Waveform of Electrical Braking The waveform for the improved electrical braking has been tested, the performance of the braking phase current has been achieve the requirement the inverter and motor. -- current for W on inverter board -- current for U on inverter board -- current for V on inverter board The braking waveform on BLDC washers. MCU-AN-510113-E-10 – Page 10 Electrical Brake V1.0.0 Chapter 3 Implementation of Electrical Braking The max phase current at the start of the electrical braking is 12.5A, and the stable value is 9.8A. The expansion waveform of electrical braking. The phase sequence of U V W is not changed , and the back-EMF is not overcharge much on the phase current. MCU-AN-510113-E-10 – Page 11 Electrical Brake V1.0.0 Chapter 3 Implementation of Electrical Braking Waveform with no optimized electrical braking the max phase current at the start of the electrical braking is 16.8A, it will destroy the IPM for long time running. The braking waveform on DD washers. The max phase current at the start of the electrical braking is 7A, and the stable value is 6.6A. The expansion waveform of electrical braking. The backEMF is not overcharge much on the phase current. 3.4 Conclusion The plug braking is realized on the washer solution of Fujitsu. And the back-EMF energy can be dissipated in the motor windings. The current overshoot at the start of electrical brake has been reduced to safe level by the special solution. MCU-AN-510113-E-10 – Page 12 Electrical Brake V1.0.0 Chapter 4 Appendix 4 Appendix 4.1 List of Figures and Tables Table 2-1: Hall Correction Theta ............................................................................................ 6 Table 2-2: Table for SVPWM Switch Rule ............................................................................. 7 Figure 2-1: Simplified Structure of Driving Hardware .............................................................. 5 Figure 2-2: SVPWM Sector Rotation for CW .......................................................................... 6 Figure 2-3: Relationship between Hall and back-EMF ............................................................ 6 Figure 2-4: Relationship between Hall and SVPWM Sector for Motor CCW ........................... 7 Figure 2-5: Lower Bridge Switching Sequence at Motor Brake ............................................... 8 Figure 3-1: PMSM Control Block with Hall Sensor Solution .................................................... 9 Figure 3-2: Flowchart for Electrical Braking .......................................................................... 10 MCU-AN-510113-E-10 – Page 13