Apec 2014 Presentation by Albert Charpentier

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Power Electronics for Renewable Energy and High Efficiency Applications

How a New Power Stack Communication System Improves IGBT Reliability and Shortens Development Time

APEC 2014Albert Charpentier, CTO

CONFIDENTIAL (c) 2014 AgileSwitch, LLC PATENTS PENDING

Overview

• Growing trend toward use of third party Stacks:– Reduce development time– Improve lifetime reliability– Better manage supply chain

• Increasing demand for Stacks with deeper monitoring and control capability:– However, parallel communications structures are limited

• Requiring a new class of Power Stacks based on a serial communication protocol that enables advanced fault and system monitoring capability.

04/10/2023 2CONFIDENTIAL (c) 2014 AgileSwitch, LLC PATENTS PENDING

Control and Communication currently used in many stack control systems today

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CPU Interface Board

IGBT Driver Board

IGBT Driver Board

IGBT Driver Board

RibbonCable

RibbonCable

Or Fiber


Pin Out of a Typical 3-Phase Power Stack Parallel Ribbon Cable

Pin No Signal Pin No Signal1 GND 2 BOT-HB1-IN3 ERROR-HBI-OUT 4 TOP-HB1-IN5 BOT-HB2-IN 6 ERROR-HB2-OUT7 TOP-HB2-IN 8 BOT-HB3-IN9 ERROR-HB3-OUT 10 TOP-HB3-IN

11 OVERTEMP-OUT 12 NC13 VDC-LINK MONITOR 14 VCC - Supply Voltage15 VCC - Supply Voltage 16 +15V17 +15V 18 GND19 GND 20 TEMP-SENSE-OUT21 GND 22 I-SENSE1-OUT23 GND 24 I-SENSE2-OUT25 GND 26 I-SENSE3-OUT

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Only 4 faults and 5 points of monitoring available


Parallel Ribbon Cable is a Communication Bottleneck Limiting Information Flow to the CPU

Current Control Signals from CPU to Interface Board:• Trigger Signals: 2 to 6• Analog Current Sensors: 1 to 3• Temperature Sensors: 1• Voltage Sensors: 1• Fault/Error Signals: 1 to 4• Power


Inverter Manufacturers Are Demanding Greater Knowledge About Stack Performance

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Pinout of a typical 3 phase Power Stack Parallel Ribbon Cable.Parallel system with analog signals limit the communication from host CPU to power stack. • More detailed error and fault information is better.• More Temperature data for each HB.• More details about error conditions• Limited ability for future improvement to information flow

without redesigning hardware.


Key Components of an Improved Interface Solution

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New Power Stack Pinout• Separate Power Supply Connector– Lower Noise, easier power distribution

• Differential Trigger Inputs– Low voltage with better noise immunity and lower EMI

• Bi-Directional Serial Interface– Simple interface for fault communication and digital sensor

information


AgileSwitch Stack

804/10/2023 CONFIDENTIAL (c) 2014 AgileSwitch, LLC PATENTS PENDING

Why a Separate Power Connector?

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Pinout of a typical 3 phase Power Stack Parallel Ribbon Cable.• Why put Power Supply Voltages on the CPU board and then over to the Power Stack?

• Supplying power over the same cable as the signal lines can cause additional noise on the control signals and make EMI shielding more difficult.

• The limited number of pins do not allow differential signals for better noise immunity.

• Power Supply distribution and isolation is easier to implement with separate power supply connector.


New Power Stack Pin Out: Trigger/Signal Lines

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Pin # Description Pin # Description1 BOT-HB1 TRIG (+) 2 BOT-HB1 TRIG(-)3 GND 4 TOP-HB1 TRIG (-)5 TOP-HB1 TRIG (+) 6 GND7 BOT-HB2 TRIG (+) 8 BOT-HB2 TRIG (-)9 GND 10 TOP-HB2 TRIG (-)

11 TOP-HB2 TRIG (+) 12 GND13 BOT-HB3 TRIG (+) 14 BOT-HB3 TRIG (-)15 GND 16 TOP-HB3 TRIG (-)17 TOP-HB3 TRIG (+) 18 GND19 RESET 20 GND21 Rx(+) 22 Rx(-)23 Fault 24 GND25 Tx(+) 26 Tx(-)

36 unique points of fault controls, monitoring and reporting


Key Features of the AgileSwitch Power Stack

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New Power Stack Pinout• Differential 3V Trigger Inputs– Can be singled ended (positive or negative active) by

grounding one side of the signal

• Manual Reset controlled by the host• Bi-directional fault line • Differential Bi-directional serial communication

system


Key Features of the Serial Interface

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New Power Stack Pinout• 5MB/sec data rate• Three 14 bit Current sensors (200KS/sec)• Three 12 bit Temperature Sensors (1KHz BW)• One 12 bit DC-Link Voltage Sensor (1KHz BW)• Fault Status Byte – with detailed fault information on

host request• On board factory set offset and linearity calibration

parameters


Bi-directional Serial Communication System Allows:

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• The timing for when the A/D current sampling occurs can be configured for each HB . The timing can either a fixed time after each trigger occurs or initiated by a second pulse on the trigger line.

• Temperature and DC-Link Voltage can be sent every sample or on request.

• Actions to be taken automatically upon a fault.• In field calibration of current, voltage and

temperature sensors.


Basic Serial Interface Protocol

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• During each sample period the following HB Packet is transmitted for each HB that is triggered:– Header Byte – defines the data to follow

• The Current measurement for the Half Bridge• Status Byte – Fault condition status for the HB• CRC Error Check sum

• Temperature and DC-Link Voltage are transmitted by request with:– Header, Temperature for all three HBs, CRC– Header, DC- Link Voltage, CRC


Amount of Data needed to Transmit

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For Each Half Bridge• Header Byte for each HB ------------------- 8 bits• Current Measurement --------------------- 16 bits• CRC for Current sensors and Fault ------- 16 bits• For all Bridges (X3) ------------------------------------------- 120 bits

For Temperature and DC-Link Voltage• Headers, Data, CRC ------------------------------------------- 70 bits

For a 10KHz system, with 5MHz data rate, 500 bits times are available; plenty of time for retransmissions


Current Sensor Sample and Hold Control

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Current Measurement is a key value necessary for the PWM control system DSP algorithm. There are two methods for controlling the A/D sample & hold and conversion. 1. Software setup via a control register to start conversion a

fixed time (100ns accuracy) after the occurrence of the IGBT trigger.

2. Double Pulse Hardware Trigger control.

Trigger Signal

IGBT On IGBT Off

Start Conversion

All pulse widths 2μs min


Current Sensor Features

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• Data transmission of the MSB begins to occur 2 after the start conversion. The total conversion time is 5.

• Each Current Measurement is a singular packet with its own CRC.

• The HB Current Measurements are transmitted in the order that the triggers are received or can be returned in a fixed order using the software configuration control registers.


Temperature and Voltage Sensor Features

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• These parameters are sampled at a continuous rate of 1KHz.

• Transmission can be configured to be sent on request or automatically.

• Automatic data transmission occurs upon successful completion of all three HB data packets

• The voltage measurement is a singular packet with its own CRC.

• All three temperature measurements are transmitted as a single packet with a CRC.


Theory of Operation

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• Each Half Bridge (HB) is considered as a separate operational event.

• When an IGBT trigger on event occurs, the A/D conversion will be started: – after the trigger and a user-defined delay, the HB start of packet byte

is sent, – followed by 16 bit current measurement, – followed by the fault status byte and the CRC.

• If HB triggers occur simultaneously then the order of transmission is HB1, HB2, HB3.


Theory of Operation (cont.)

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• If a Receiver error occurs, the host can request a re-transmission via the Fault signal over the Serial Input. The retransmission will occur after the transmission of the current packet is complete.

• Managing each Half Bridge (HB) as a separate operational event with its own data packet minimizes synchronization issues and optimizes bandwidth if transmission errors occur.

• The lower speed parameters, temperature and voltage can be requested by the host when needed.


8 Bits

Timing for an HB Current Sensor

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Trigger Signal

Period

Packet Header

MSB8 Bits LSB

Status Byte

Current

16 bits

Check Sum

8 Bits

Next HB

Total 40 bits at 5MHz = 8μs

User config delay


Fault Management

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Each HB has a status word that is sent with the packet after a trigger event. The status byte contains a code to indicate the status of the various faults for that HB.

1. DSAT 2. Overcurrent condition3. Over Temperature4. Under Voltage HI Side or Lo Side5. Overshoot Hi Side or Low Side6. Crossover error7. Over Voltage8. Active Clamping Monitor


Fault Recording – Stack BlackBox™

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The AgileSwitch Stack continually stores the state of the system in a buffer. In the event of a fault:– The last 8 states are stored in EEPROM.– Each time a fault occurs the data is stored. Up to 1,000

fault occurrences can be stored.– This takes 5ms to store and occurs even with loss of power.– This information can be retrieved for future failure

analysis.


The Future of Improved Communications

• Data from advanced monitoring, augmented by predictive analytics, helps pre-empt system failure and adjusts overall system performance accordingly.

• These new third party Stacks can increase system lifetime beyond that of conventional systems.

• Further, these programmable and hardware configurable Stacks shorten development times and lower supply chain risks and costs through multi-sourcing of IGBTs.


Conclusion

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• The New AgileSwitch Stack marks a major step toward improving design time and system reliability.

• We are evolving to a more connected world, with a focus on “the Internet of Things” and Power Stacks need to become more connected.

• Our new serial interface can accommodate future improvement and expanded connectivity via IEEE 1588 protocols.

• This will allow even simpler wiring with better control, isolation and reliability.


Contact

AgileSwitch, LLC1650 Arch Street, #1905Philadelphia, PA 19103 [email protected]

2604/10/2023 CONFIDENTIAL (c) 2014 AgileSwitch, LLC PATENTS PENDING

mailto:[email protected]

Apec 2014 Presentation by Albert Charpentier

Technology

Transcript of Apec 2014 Presentation by Albert Charpentier