An High Voltage CMOS Voltage Regulator for automotive alternators with programmable functionalities and full reverse polarity capability

Transcription

1 L. Fanucci, G. Pasetti University of Pisa P. D Abramo, R. Serventi, F. Tinfena Austriamicrosystems P. Tisserand, P. Chassard, L. Labiste - Valeo An High Voltage CMOS Voltage Regulator for automotive alternators with programmable functionalities and full reverse polarity capability Speaker: Francesco TINFENA austriamicrosystems AG Pisa - Italy

2 Motivation and basic idea Fuel reduction programs of car makers Improvement of efficiency of automotive alternators Demand of interfaced regulators with customized functions Reduction of the development lead time for the new generation of smart regulated alternators Innovative and effective approach for design and test of regulators for automotive alternators Demonstrator with programmable functions that can be changed during the development phase Test on vehicle Releasing of the final customized version of the regulator 2

3 Summary Introduction Regulators for automotive alternators brief description state of the art Proposed innovative and effective new approach for design and test Implemented prototype description Electronics for interfaces (HV Integrated Circuit) Electronics for algorithm (programmable logic) Measurement results Conclusions 3

4 Introduction This work presents the development, the realization and the measurement results of a regulator demonstrator achieved combining an IC implemented in austriamicrosystems AG (AMS) HVCMOS 0.35μm technology a Valeo Engine and Electrical Systems mechatronic regulator standard module mounted on an alternator The research leading to these results has received funding from the European Community's Seventh Framework Programme under grant agreement n (project ATHENIS) 4

5 Automotive alternators (1) Electro-mechanical machines Convert part of the mechanical energy from the car engine into electrical energy FRONT BRACKET ROTOR REAR BRACKET RECTIFYING BRIDGE STATOR Supply all the electrical loads of the vehicle REAR COVER 5

6 Automotive alternators (2) Voltage amplitude of the stator phases depends on the biasing current of the rotor coil and on its rotational speed FRONT BRACKET ROTOR REAR BRACKET RECTIFYING BRIDGE STATOR REAR COVER Diode bridge rectifies the alternating voltage on the stator phases generating the DC voltage 6

7 Regulator for alternators Smart part of the alternator Regulator functions are fully integrated in a mechatronic module, which includes an ASIC Among the most complex System on Chip (SoC) on the car regulation loop external functions control harshest automotive reliability requirements high operating junction temperature ( > 150 C) high current (up to 4 A operating, 8 A absolute) high voltage and reverse polarity ESD, EMC, harness pulses and ground shift 7

8 Regulated Alternator Rotor belt driven by the pulley Rotor coil biased by the ASIC through the brushes Brush-Holder includes the ASIC die, the connectors to the Power Machine and the external world DC voltage obtained rectifying stator phases supplies the battery and the vehicle loads 2 phases are connected to the ASIC for rotational speed and voltage detection Sense pin for regulation 8

9 Mechatronic brush-holder BRUSHES PH1 PH2 ASIC DIE GROUND HEAT SINK BATTERY Front CONNECTOR Rear 9

10 Regulation loop ASIC Feedback chain senses the voltage on the battery and converts it to the digital domain Proportional or Proportional-Integral error corrector acts on the amplitude of excitation field of rotor coil Direct chain includes power electrical stages Stability issues 10

11 State of the art Long development lead time for regulated alternators Design of Electronics for interfaces, mainly analog and HV with automotive requirements Design of Electronics for algorithms, digital with regulation functions Dice manufacturing, assembly in mechatronic mock-up and performance evaluation Some iterations to get the final silicon Analysis of regulation loop stability is critical Regulation functions are integrated, but the loop includes the alternator and the loads Risk to have an unstable regulator when the designed SoC is used in another vehicle platform 11

12 Challenges New generation of alternator regulators Additional functions to improve efficiency Flexibility: software configuration for multiple car platforms Low cost CMOS technology combining flexibility and harshest automotive requirements Full reverse polarity capability Reduction of development lead time Possibility to change, whenever needed in the design phase, the implemented functions, including regulation Possibility to check properties, including loop stability, before releasing the final version 12

13 Proposed solution Development of a regulator demonstrator that can be mounted in a standard brush-holder includes interfaces and algorithms allows direct test in a real vehicle application Electronics for interfaces designed to fulfill all possible automotive requirements for regulators including full reverse polarity Electronics for algorithm fully programmable in a short time Possibility to test various algorithm and different control loop solutions and validate them in the specific application Reduced risks and costs of design changes Increased possibility to adapt the product to new requirements 13

14 Implemented prototype system (1) Electronics for interfaces fully integrated in an integrated circuit (IC) designed and manufactured in austriamicrosystems HV CMOS 0.35μm technology Electronics for algorithm implemented in a FPGA 3 wire serial communication between IC and FPGA IC and FPGA mounted in a standard Valeo brushholder IC is assembled directly on the leadframe FPGA is soldered on a mezzanine PCB that fits the area in the brush-holder 14

15 Implemented prototype system (2) IC FPGA 15

16 Implemented prototype system (3) Standard Valeo brushholder with the IC Mezzanine board with the FPGA 16

17 IC Design Block diagram Signal adaptation and conversion Power MOS and freewheeling diode 7 main blocks 1. Battery voltage management 2. Phase management 3. ECU Communication 4. Ignition management 5. Serial transmission 6. Excitation stage 7. Power management 17

18 IC design - Properties Converts sensed battery voltage to digital and sends the feedback DATA to the FPGA Monitors the battery sense path and informs FPGA sense cable connected or not (SD) abnormal voltage between sense and battery (BSDVD) Monitors speed (RSD) and amplitude (PVD) of phases Manages communication with ECU (CR, CT) and user interfaces (key insertion and alert lamp) Exchange data frames with FPGA (serial interface) Wakes up the FPGA if key is turned ON or engine starts rotation or activity from ECU is detected 18

19 IC design Power Stage VBAT Bulk driver High side PMOS Reverse battery protection VBAT Psub Charge pump NOT necessary EXC PWM driven by EXCCTRL signal EXC GND brush brush Rotor Linear slope controlled current transient between PMOS and freewheeling diode High side current detection circuit 19

20 FPGA programming Synthesizable HDL code Programmable electronics for algorithms Regulation implementation Feedback voltage converted to digital received from electronics for interfaces (IC) Algorithm generates the duty cycle of the rotor excitation driver and sends the signal to the IC Communication with IC 256 frames, 44 bits, 250 Hz MHz Control of alternator functionalities Coding/decoding of ECU communication State of alarm lamp and system power-off 20

21 Main advantages Different loop control solution can be tested Various algorithm for alternator control and monitor can be verified Proposed mixed signal architecture with programmable algorithm solves many stability issues that arise during regulator development when the regulated alternator is transferred from one vehicle platform to another Algorithm already verified with FPGA can be then implemented in a digital part of the final ASIC 21

22 Evaluation IC manufactured and assembled with FPGA in the brush-holder Standby current < 200μA Serial communication OK Reverse voltage protection on all pins OK ECU communication and Ignition Management OK Battery Voltage sense and monitor OK Phase management OK Power management OK, PSRR improvement planned Excitation Stage OK ON resistance and slope control High side current read 22

23 Current slope control Fixed duty cycle on the high side generates an almost constant current in the rotor coil Slope controlled current transition between high-side PMOS and freewheeling diode (for EMC compliance) 12 V -1 V EXC EXC IHS High side current (IHS) switching transient IHS 2μs High side turn-on sequence Negative voltage on rotor coil pin (EXC) when IHS=0 (diode is ON) Slope: 500mA / μs 23

24 High-side PMOS Ron ON Resistance PMOS Junction Temperature ( C) Simulated R (mω) Measured R (mω) ON resistance of high-side PMOS < 150 C Minimizes the self-heating of the device P dis =R on (I rot ) 2 24

25 Reverse voltage protection Pin VBAT PHASE1 PHASE2 COMM. RX COMM. TX DF SENSE KEY LAMP Reverse voltage protection Voltage (V) Simulated current (ua) a b 3815 b Measured current (ua) a b 3968 b a. Internal pull-up resistor b. Internal pull-down resistor 25

26 Regulation loop stability Complete system closed loop transfer function Including alternator, IC, FPGA, wiring, battery 40 Black diagram 30 Athenis_6Krpm_Exc50pc Athenis_10krpm_EXC50pc Gain (db) 0-10 GAIN MARGIN > 15 db PHASE MARGIN > 60 STABLE Phase ( ) 26

27 Alternator measurements Regulated Voltage vs Output Current delivery 210mV voltage drop as expected in the spec 27

28 Complete alternator prototype CONNECTOR PULLEY BRUSH-HOLDER FPGA PROGRAMMING INTERFACE 28

29 Conclusions Regulated alternators are important in power train system to decrease fuel consumption Major challenge is to meet time-to-market keeping flexibility to implement upcoming customer functions minimizing risk related to stability issues Proposed innovative approach with FPGA and IC is an important step The alternator prototype with programmable functions has been successfully tested on bench and vehicle Electronics for algorithms implemented in the FPGA and verified on system can be transferred to the digital part of the final ASIC for regulator 29