Microchip Technology dsPICDEM MC1H User Manual

dsPICDEM™

MC1H 3-Phase

High Voltage Power Module

User’s Guide

 2003 Microchip Technology Inc. DS70096A

Note the following details of the code protection feature on Microchip devices:

• Microchip products meet the specification contained in their particular Microchip Data Sheet.

• Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions.

• There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip's Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property.

• Microchip is willing to work with the customer who is concerned about the integrity of their code.

• Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.”

Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.

Information contained in this publication regarding device applications and the like is intended through suggestion only and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. No representation or warranty is given and no liability is assumed by Microchip Technology Incorporated with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. Use of Microchip’s products as critical components in life support systems is not authorized except with express written approval by Microchip. No licenses are conveyed, implicitly or otherwise, under any intellectual property rights.

Trademarks

The Microchip name and logo, the Microchip logo, dsPIC,

EELOQ, MPLAB, PIC, PICmicro, PICSTART, PRO MATE and

K PowerSmart are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.

FilterLab, microID, MXDEV, MXLAB, PICMASTER, SEEVAL and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A.

Accuron, Application Maestro, dsPICDEM, dsPICDEM.net, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, InCircuit Serial Programming, ICSP, ICEPIC, microPort, Migratable Memory, MPASM, MPLIB, MPLINK, MPSIM, PICC, PICkit, PICDEM, PICDEM.net, PowerCal, PowerInfo, PowerMate, PowerTool, rfLAB, rfPIC, Select Mode, SmartSensor, SmartShunt, SmartTel and Total Endurance are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.

Serialized Quick Turn Programming (SQTP) is a service mark of Microchip Technology Incorporated in the U.S.A.

All other trademarks mentioned herein are property of their respective companies.

Printed on recycled paper.

Microchip received QS-9000 quality system certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona in July 1999 and Mountain View, California in March 2002. The Company’s quality system processes and procedures are QS-9000 compliant for its PICmicro devices, Serial EEPROMs, microperipherals, non-volatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001 certified.

8-bit MCUs, KEELOQ

code hopping

DS70096A-page ii  2003 Microchip Technology Inc.

dsPICDEM™ MC1H 3-PHASE

HIGH VOLTAGE POWER MODULE

Safety Notice

The safety notices and operating instructions provided should be adhered to, to avoid a safety hazard. If in any doubt, consult your supplier.

WARNING – This system must be earthed (grounded) at all times.

CAUTION – The system should not be installed, operated, serviced or modified except by qualified personnel who understand the danger of electric shock hazards and have read and understood the user instructions. Any service or modification performed by the user is done at the user’s own risk and voids all warranties.

WARNING – The output terminals are NOT isolated from the incoming AC mains supply and may be at up to 410V with respect to ground, regardless of the input mains supply voltage applied. These terminals are live during operation AND for 3 minutes after disconnection from the supply. Do not attempt to access the terminals or remove the cover during this time. Note that this same shock hazard applies to any external brake resistor connected, which will also be live, and therefore protection equivalent to double insulation should be provided.

WARNING – The unit may obtain power through the output terminals if these are connected to a rotating motor acting as a generator. If this is the case, then the previous warning also applies (i.e., the output terminals are live when connected to the generator and for 3 minutes after the generator has been stopped). Note that this case can arise even when the unit has been disconnected from the incoming AC mains supply.

CAUTION – If a motor is connected to the output of this unit, the frame should be connected to the output protective ground terminal provided. Particular care should be taken to mechanically guard such a motor, bearing in mind that unexpected behavior is likely to result from the process of code development.

CAUTION – For continued protection against the risk of fire, replace the fuse with one of the same type only (i.e., T5A H 250V, Time Lag 5A High Breaking Capacity 250V minimum).

dsPICDEM™ MC1H 3-Phase High Voltage Power Module

• The system is intended for evaluation and development purposes and should only be operated in a normal laboratory environment as defined by IEC 61010-1:2001.

• Clean with a dry cloth only.

• Operate flat on a bench, do not move during operation and do not block the ventilation holes.

• The system should not be operated without all the supplied covers fully secured in place.

• Screws should not protrude into the unit by more than 5 mm (0.2″), type M3 ISO metric.

• The system should not be connected or operated if there is any apparent damage to the unit.

• The unit is designed for installation category II and to be connected to the AC mains supply via a standard non-locking plug. As the unit has no mains switch, this plug constitutes the means of disconnection from the supply and thus the user must have unobstructed access to this plug during operation.

dsPICDEM™ MC1H 3-PHASE

HIGH VOLTAGE POWER MODULE

Table of Contents

Safety Notice ............................................................................................................................ iii

Preface........................................................................................................................................ 1

Chapter 1. Set Up and Operation

1.1 Introduction ................................................................................................................... 5

1.2 Using The Motor Control 3-Phase High Power Module ................................................ 7

1.3 Current and Power Limitations.................................................................................... 14

1.4 Detailed Description of Operation ............................................................................... 17

1.5 Modifying The Board ................................................................................................... 30

1.6 Test Points .................................................................................................................. 36

1.7 User Signal Connector Pinout (37-Pin, D-Type) ......................................................... 37

Appendix A: Circuit Diagrams ........................................................................................... 39

Appendix B: Source Code................................................................................................... 47

Worldwide Sales and Service.............................................................................................. 54

 2003 Microchip Technology Inc. DS70096A-page v

dsPICDEM™ MC1H 3-Phase High Voltage Power Module

NOTES:

This chapter contains general information about this manual and contacting customer support.

HIGHLIGHTS

Topics covered in this chapter:

• About this Guide

• Warranty Registration

• Recommended Reading

• The Microchip Web Site

• Development Systems Customer Notification Service

• Customer Support

ABOUT THIS GUIDE

Document Layout

dsPICDEM™ MC1H 3-PHASE

HIGH VOLTAGE POWER MODULE

Preface

This document describes how to use the Microchip dsPICDEM™ MC1H High Voltage 3-Phase Power Module. The manual layout is as follows:

• Chapter 1: Set Up and Operation – Describes what the product is, what makes it

a desirable development tool, how to install it and the basic features of the interface.

• Worldwide Sales and Service – Lists Microchip sales and service locations and

telephone numbers worldwide.

Documentation Updates

All documentation becomes dated and this user’s guide is no exception. Since MPLAB customer needs, some actual dialogs and/or tool descriptions may differ from those in this document. Please refer to our web site to obtain the latest documentation available.

IDE, MPLAB C1X and other Microchip tools are constantly evolving to meet

Documentation Numbering Conventions

Documents are numbered with a “DS” number. The number is located on the bottom of each page, in front of the page number. The numbering convention for the DS Number is: DSXXXXXA,

where:

XXXXX = The document number.

A = The revision level of the document.

dsPICDEM™ MC1H 3-Phase High Voltage Power Module

WARRANTY REGISTRATION

Please complete the enclosed Warranty Registration Card and mail it promptly. Sending in your Warranty Registration Card entitles you to receive new product updates. Interim software releases are available at the Microchip web site.

Chapter 1. Set Up and Operation

1.1 INTRODUCTION

The Microchip dsPICDEM MC1H 3-Phase High Voltage Power Module is intended to aid the user in the rapid evaluation and development of a wide variety of motor control applications using the dsPIC Microchip analog components, as well as a PIC isolated voltage feedback. The main components of the system are shown in Figure 1-2.

The rated continuous output current from the inverter is 2.5A (RMS). This allows up to approximately 0.8 kVA output when running from a 208V to 230V single-phase input voltage in a maximum 30°C (85F) ambient temperature environment. Thus, the system is ideally suited to running a standard 3-Phase Induction Motor of up to 0.55 kW (0.75 HP) rating or an industrial servomotor of slightly higher rating. The power module is capable of driving other types of motors and electrical loads that do not exceed the maximum power limit and are predominantly inductive. Furthermore, single-phase loads can be driven using 1 or 2 of the inverter outputs.

The unit is capable of operating from any AC voltage up to a maximum of 265V. Operation at voltages beneath 208V requires that the output power is reduced owing to inverter output and AC input stage current limits. A more detailed explanation of power limitations is given in Section 1.4 “Detailed Description of Operation”.

The user should read Section 1.3 “Current and Power Limitations” and Section

1.4 “Detailed Description of Operation” carefully before using the system.

dsPICDEM™ MC1H 3-PHASE

HIGH VOLTAGE POWER MODULE

microcontroller. The design of the system includes

microcontroller used to provide

FIGURE 1-1: POWER MODULE WITH ATTACHED DEVELOPMENT BOARD

(SOLD SEPARATELY)

dsPICDEM™ MC1H 3-Phase High Voltage Power Module

FIGURE 1-2: MC1H 3-PHASE HIGH VOLTAGE POWER MODULE BLOCK DIAGRAM

R, Y, B Switch Current

To Gate

Drive 1-8

From

Control

Board

Gate Drive Optoisolation

R & Y Isolated Phase Current Feedback

DC Bus Voltage DC Bus Current

Brake Chopper

Corrector

Power Factor

Vac

Brake Switch

Fault

PICmicro

Current

Detection

MCU

Live Side

Isolated Side

Control

Board

Feedback Optoisolation

Isolated DC Input

Current Feedback

Live

Neutral

Vac

DC BUS Voltage

0 - 265V AC

Set Up and Operation

1.2 USING THE MOTOR CONTROL 3-PHASE HIGH POWER MODULE

1.2.1 Introduction

The user should be aware of the operating procedures outlined below and ensure that they are followed. Failure to do so may result in damage to the system.

1.2.2

It is recommended that cables be terminated with blue or red insulated crimp terminals. If crimp terminals are not used, care should be taken to ensure that stray strands of wire do not short to adjacent terminals or the enclosure. If possible, all wires should be stripped and tinned with solder before connecting to the power module terminals.

For the AC mains supply input, standard double-insulated, 3-core flex cable should be used with a minimum current rating of 10A (1 mm can be used when the IEC connector is removed.

Note: The system is designed for installation category II. Therefore, the incoming

The recommended output cable size is 1.0 to 1.5 mm have a 600V rating. This cable should also be double insulated or have a protective ground screen.

Access to the terminal screws is provided via holes in the lid of the enclosure. A flat blade screwdriver should be used.

Note: The user should only access the power terminals when the system is fully

The power connections are shown in Table 1-1 and Figure 1-3:

Making Power Connections

18 AWG). A computer power cable

mains cable should be wired into a standard non-locking 2-pin + ground type plug.

(18-16 AWG) and it should

discharged (see Safety Notice).

TABLE 1-1: POWER CONNECTIONS

Connection Number Input Output

1 Ground Ground 2 Neutral Red Phase 3 Live (Fused) Yellow Phase 4 — Blue Phase 5 — -DC Bus 6 — External Brake Resistor 7—+DC Bus

dsPICDEM™ MC1H 3-Phase High Voltage Power Module

FIGURE 1-3: POWER CONNECTIONS

Output

Input

3 2 1

Using output connections 6 and 7, the user may connect an external braking resistor. The user should consider the maximum and average power to be dissipated at the required DC bus voltage when considering the resistor value. They should also consider the peak allowable resistor current of 4A. For example, if regulating at 400V then a 100Ω minimum value should be used which would allow 1.6 kW (at most) to be dissipated.

The user may feed in an external DC supply using output connections 5 and 7. This offers the simplest way for a user to bypass the PFC section of the unit. In the simplest case all the user needs to do is use an external rectifier and fuse. The input current rating when using the auxiliary DC input is 15A (RMS). The inverter output rating is unchanged. Note that if using the auxiliary DC input, the internal fuse, soft-start, PFC and ground FAULT protection is bypassed. It is up to the user to ensure adequate external protection circuitry is used and incoming DC voltage is correctly regulated.

6 5 4 3 2 1

1.2.3

Connecting To The Control Board

The system has been designed so that the Microchip dsPICDEM MC1 Motor Control Development Board (02-01648) plugs directly into the 37-pin, D-Type connector. Section 1.7 “User Signal Connector Pinout (37-Pin, D-Type)” contains details of the pin allocation.

Correct operation with the use of an extension cable can not be guaranteed as it may introduce additional noise. If an extension is used, it should be as short as possible and use screened cable.

The power module derives its low voltage power supplies from the control PCB. The supplies on the isolated supply are taken directly from the control PCB via the 37-pin connector. The supplies on the live side of the isolation barrier are derived using an isolating DC-DC converter that is connected to the digital +5V supply input on the 37-pin connector. In this way, the power module may be used at any input voltage up to the maximum. This arrangement is shown in Figure 1-4.

Set Up and Operation

FIGURE 1-4: POWER ELECTRONICS GATE DRIVE STAGES

Power PCB 02-01647

POWER ELECTRONICS GATE DRIVE

STAGES

INCOMING GROUND

CONNECTED TO

CHASSIS

9V Power

Supply Input

(Floating)

+15V OUT

ISOLATING

DC : DC

CONVERTER

Smooth and

Regulate

DETECTION

AND LATCHING

5V LINEAR

REGULATOR

Rectify

FAULT

CIRCUITRY

OPTOCOUPLERS

Pin 19&37

Digital +5V

Digital 0V

To Digital

Circuits

Control PCB 02-01648

CONDITIONING

OF LIVE

FEEDBACK

SIGNALS

ISOLATED

HALL-EFFECT

CURRENT

TRANSDUCERS

Pin 18&36

Analog +5V

To Analog

Circuits

Pin 9

LIVE

ISOLATED

Pin 27

Analog 0V

Note that the incoming digital 0V from the development board is grounded within the power module (as shown in Figure 1-4) to ensure user safety. When a PC or any other device is connected to the control board there is therefore the possibility of a “ground loop” occurring. If this is suspected, the user should first try to eliminate the stray magnetic field causing the problem by relocating the offending transformer or by using shielding. If this is not possible, then the equipment connected to the development board should be isolated from the digital 0V.

Position and speed feedback transducers are connected to the control board directly and not via the power module. No electrical isolation is provided on the control board for these signals and so the transducers must be isolated.

Consult the development board documentation for details of signal interfacing and how to connect in-circuit emulators and debugging equipment.

dsPICDEM™ MC1H 3-Phase High Voltage Power Module

1.2.4 Power-Up/Power-Down Sequence

The user should ensure that the following sequence are followed.

1.2.4.1 POWER-UP SEQUENCE

• With the development board plugged in, turn on the power supply feeding the control PCB (if not already on).

• One or more of the fault lights may illuminate. This is normal.

• Turn on the AC supply to the power module.

• Reset the system by activating the active high ISO_RESET line. The ISO_RESET line is on pin 33 of the 37-pin, D-type (see Section 1.7 “User Signal Connector Pinout (37-Pin, D-Type)”). If using the dsPICDEM MC1 Motor Control Development Board, this signal is routed to pin 14 of the 30F6010 dsPIC device, which is on Port RE9. The minimum pulse width for the RESET is 2 µs. The RESET should be done in coordination with the SPI™ handling routine of the dsPIC device to ensure correct synchronization of the serial interface providing the isolated voltage feedback (see Section 1.2.6.2 “Isolated Feedback” and Section 1.4.7.2 “Isolated Voltage Feedback”). The system is now ready to use.

1.2.4.2 POWER-DOWN SEQUENCE

• Stop firing all power devices.

• Turn off the incoming AC supply.

• Wait until the red DC bus LED indicator visible through the ventilation holes in the top of the unit has gone out (this will take 3 minutes or less).

• Turn off the power supply feeding the control card (if required).

1.2.5

The PFC stage has been designed for a switching frequency of 50 kHz (±5%).

This offers a good system compromise between cost, size and efficiency. The modulation frequency affects not only the losses in the power switches and diode but also that in the PFC inductor and snubbing components. The user should not deviate from the stated carrier frequency. The user should note that a typical regulation level for the DC bus is between 350-400V.

If the user does not wish to use the PFC stage the PFC switches can simply be left off. However, the PFC inductor and diode will be left in circuit and the input current will remain limited to 5A (RMS) and 8.9A Peak. The user should read Section

1.5.3.3 “Bypassing The PFC” if this is unacceptable.

The Brake chopper switch has been designed so that it may be switched up to a maximum frequency of 16 kHz. This frequency limit is chosen for power dissipation

and low voltage power supply consumption reasons. In most braking applications a lower modulation frequency will be used, as there is little benefit (apart from acoustic noise) from modulating at such a high frequency.

The six inverter switches have been designed so that they may be switched up to a maximum frequency of 20 kHz. This frequency limit is chosen for power

dissipation and low voltage power supply consumption reasons. Unless extremely low output current harmonics or very high bandwidth control is required, it is suggested that a 16 kHz carrier frequency be used. This offers lower loss while still being inaudible. It also has the advantage that the dead time insertion will cause less distortion of the output voltage.

Power Device Switching Frequencies

Set Up and Operation

Given the high side and low side switches of the inverter are connected in series across the DC bus (see Figure 2.1), both switches should never be turned on at the same time. Turning both switches on effectively places a short circuit across the DC bus and is called “Shoot Through”. Shoot Through should be avoided at all costs. In order to avoid Shoot Through, an appropriate time delay must be inserted between the turn off command to one device and the turn on command to the other device of the same inverter leg. This time is called the “Dead Time”. The required Dead Time depends on the switching speeds of the power devices and the timing delays due to the optocouplers and the gate drive circuits.

Note: No hardware Dead Time is included in the design as it is included as a

feature of the Motor Control PWM Module of the dsPIC device. A minimum Dead Time of 2 µs should be used. This applies to both turn on and turn off of both devices.

Writing to the appropriate registers in the dsPIC device (DTCON1 and DTCON2) sets the dead time. Refer to the dsPIC30F Family Reference Manual (DS70046) for details.

Although not necessary for correct operation of the system, it is common practice to eliminate very narrow firing commands. This is because they will have negligible effect on the output waveform but incur additional switching loss. It is suggested that a duty cycle that gives transistor on or off times of less than 100 ns be eliminated by rounding the duty cycle up or down as appropriate. Note that pulses, which are narrower than the dead time set in the Motor Control PWM Module, are automatically eliminated.

Note: The user should verify that all PWM frequencies and dead time settings are

correct using an oscilloscope before connecting the control signals to the power module.

In order to provide an economic design, so-called bootstrap power supplies are used for the high side inverter switches (see Section 1.4.3.3 “Gate Drive” for details). As the charging path for these is only made when the corresponding low side switch or diode conducts, this places some minor restrictions on modulation. These are as follows:

1. When the power module is first energized after a period of time where no modulation has taken place, all low side switches should be turned on for 2-3 µs. This ensures the bootstrap supplies are “primed”. This can be simply done by using the output override facility in the dsPIC Motor Control PWM module by setting the correct bits in the OVDCON register. Care should be taken to ensure a shoot through does not accidentally occur. The possibility of a shoot through fault will be minimized if the dsPIC PWM module is operated in the complementary Output mode (module default).

2. If the user is continuously modulating all the low side switches as part of their PWM strategy, the “priming” step is not strictly necessary, as it will happen automatically. There will however be a delay of variable duration before the high side switches actually fire. The delay will depend on the particular operating circumstances and whether it is acceptable or not will depend on the particular application.

3. In extreme circumstances, it is possible that the high side bootstrap supply will discharge while the system is running. This will not happen for typical sinusoidal modulation schemes provided an inductive load (e.g., a motor) is connected. If a bootstrap supply collapses, an under-voltage lockout will automatically occur to protect the high side switch entering the linear region of operation. The high side switch is turned off whatever the command. The lockout is automatically cleared when the bootstrap supply is restored and the next turn-on edge occurs. If necessary, the user should periodically apply a refresh pulse to the low side switch in a similar manner to that described for priming above.

dsPICDEM™ MC1H 3-Phase High Voltage Power Module

1.2.6 Power Module Feedback Signals

1.2.6.1 INTRODUCTION

The power module may be operated in two distinct ways with respect to signal isolation. This effects which of the feedback signals are available. All feedback signals are preconditioned and scaled within the power module. Which particular set of feedback signals the user requires will change depending on the application. Typically industrial applications tend to use isolated signals for both safety, noise and performance reasons. More cost-sensitive applications, and especially those that have little or no user input, tend to run the control electronics live and use non-isolated feedback signals.

1.2.6.2 ISOLATED FEEDBACK

Table 1-2 gives the scaling of the isolated feedback signals as the system is delivered.

TABLE 1-2: ISOLATED SCALING

Feedback Signal Scaling

Inverter Output (R and Y) Hall Current Sensor 2.4 A/V with 2.5V = 0A DC Input Hall Current Sensor 4.8 A/V with 2.5V = 0A DC Bus Voltage via SPI™ Channel 230 = 410V (1LSB = 1.78V) Rectified AC Voltage (|VAC|) via SPI Channel 230 = 369V (1LSB = 1.60V)

1.2.6.3 NON-ISOLATED FEEDBACK

As the system is delivered, access is not given to the non-isolated feedback signals to ensure user safety. If an experienced user wishes to access these signals they should read Section 1.4 “Detailed Description of Operation” along with Section

1.5.3.4 “Accessing the Additional (non-isolated) Feedback Signals”. Note that once the isolation barrier is bridged, all signals can no longer be considered to be isolated from the power circuit. When operating in the non-isolated configuration, the Hall current sensors and SPI voltage feedback signals are also available.

The scaling for the signals as the system is delivered is given below. For details of changing the scaling, see Section 1.5.3 “Changing Current Feedback and Trip

Scaling”.

TABLE 1-3: NON-ISOLATED SCALING

Feedback Signal Scaling

R, Y, B Inverter Leg Shunts 2.4 A/V with 2.5V = 0A* DC Bus Shunt 2.38 A/V with 2.5V = 0A* Brake Chopper Shunt 1.09 A/V DC Bus Voltage 91.0 V/V |VAC| Voltage 81.9 V/V R. Y, B Inverter Output Voltages 92.0 V/V

* If a large rate of change of current occurs due to the use of a load with low inductance, the

voltage across the self-inductance of the shunts will cause an additional shunt voltage that will add to the shunt feedback signals.

Set Up and Operation

1.2.7 FAULT Protection

The following FAULT protection is provided which automatically disables all firing independent of the inputs on the 37-pin connector.

TABLE 1-4: FAULT PROTECTION

Fault Source

R, Y, B Bottom Switch Current DC Bus Current DC Bus Voltage Brake Switch Current Heat sink Over Temperature Isolated DC Input Current Feedback R, Y Isolated Phase Current Feedback

* If a large rate of change of current occurs due to the use of a load with low inductance, the

voltage across the self-inductance of the shunts will cause trips to occur at a lower level than that stated.

To reset a FAULT, assert the ISO_RESET line of the 37-pin connector. This should be done for a minimum time of 2 µs. The RESET must be carried out in coordination with the SPI handling routine of the dsPIC device to ensure correct synchronization of the serial interface providing the isolated voltage feedback (see Section 1.4.7.2 “Isolated Voltage Feedback”).

Nominal Trip

Level

±4.8A* ±4.8A*

410V

+4.9A

65°C (150F)

+8.9A ±4.4A

LED Indicator

Shunt Overcurrent

Over Voltage Brake Overcurrent Over Temperature

Hall Overcurrent

Note: If SHUNT OVERCURRENT trips are occurring, but not HALL

OVERCURRENT trips, this may indicate that an inverter Shoot Through is occurring. The user should immediately remove AC power from the system and check that the correct 2 µs dead time exists on the inverter firing signals using an oscilloscope.

1.2.8

Operation at Low Output Frequencies and Stall

As far as the inverter power devices are concerned, it is the instantaneous temperatures of their junctions that matter for correct operation and reliability. As the current that flows through a particular power device changes through an electrical cycle so does the loss. At high fundamental output frequencies (e.g., 60 Hz), the devices have sufficient thermal “mass” to smooth out much of the effect of the variation in loss, so that the peak device junction is due to the (much lower) average dissipation. As the output frequency reduces, the peak device junction temperature reaches the worst case loss.

It is common practice to include a stall detection algorithm in software. This is designed to not only protect the power components, but also the motor from thermal overload. As it is impractical to include stall detection in hardware that maintains flexibility for development but still provides 100% protection, it is assumed that the software in the dsPIC device provides this feature. The algorithm should monitor rotor speed and cause a system trip if the rotor speed is at or near zero for greater than an appropriate length of time while the inverter is energized. A stall trip time of 2 seconds is suggested.

+ 42 hidden pages

Microchip Technology dsPICDEM MC1H User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Chapter 1. Set Up and Operation

1.1 INTRODUCTION

1.2 USING THE MOTOR CONTROL 3-PHASE HIGH POWER MODULE

1.2.1 Introduction

Making Power Connections

Connecting To The Control Board

1.2.4 Power-Up/Power-Down Sequence

Power Device Switching Frequencies

1.2.6 Power Module Feedback Signals

1.2.7 FAULT Protection

Operation at Low Output Frequencies and Stall