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Application Note
Inverter Control by V850 Series
120° Excitation Method Control by Zero-Cross Detection
V850E/IA1
V850E/IA2
V850E/IA3
V850E/IA4
V850E/MA3
Document No. U17209EJ1V0AN00 (1st edition)
Date Published September 2004 N CP(K)
2004
Printed in Japan
[MEMO]
2
Application Note U17209EJ1V0AN
NOTES FOR CMOS DEVICES
1
VOLTAGE APPLICATION WAVEFORM AT INPUT PIN
Waveform distortion due to input noise or a reflected wave may cause malfunction. If the input of the
IL
CMOS device stays in the area between V
malfunction. Take care to prevent chattering noise from entering the device when the input level is fixed,
and also in the transition period when the input level passes through the area between V
IH
(MIN).
V
HANDLING OF UNUSED INPUT PINS
2
Unconnected CMOS device inputs can be cause of malfunction. If an input pin is unconnected, it is
possible that an internal input level may be generated due to noise, etc., causing malfunction. CMOS
devices behave differently than Bipolar or NMOS devices. Input levels of CMOS devices must be fixed
high or low by using pull-up or pull-down circuitry. Each unused pin should be connected to V
via a resistor if there is a possibility that it will be an output pin. All handling related to unused pins must
be judged separately for each device and according to related specifications governing the device.
3
PRECAUTION AGAINST ESD
A strong electric field, when exposed to a MOS device, can cause destruction of the gate oxide and
ultimately degrade the device operation. Steps must be taken to stop generation of static electricity as
much as possible, and quickly dissipate it when it has occurred. Environmental control must be
adequate. When it is dry, a humidifier should be used. It is recommended to avoid using insulators that
easily build up static electricity. Semiconductor devices must be stored and transported in an anti-static
container, static shielding bag or conductive material. All test and measurement tools including work
benches and floors should be grounded. The operator should be grounded using a wrist strap.
Semiconductor devices must not be touched with bare hands. Similar precautions need to be taken for
PW boards with mounted semiconductor devices.
(MAX) and VIH (MIN) due to noise, etc., the device may
IL
(MAX) and
DD
or GND
4
STATUS BEFORE INITIALIZATION
Power-on does not necessarily define the initial status of a MOS device. Immediately after the power
source is turned ON, devices with reset functions have not yet been initialized. Hence, power-on does
not guarantee output pin levels, I/O settings or contents of registers. A device is not initialized until the
reset signal is received. A reset operation must be executed immediately after power-on for devices
with reset functions.
5
POWER ON/OFF SEQUENCE
In the case of a device that uses different power supplies for the internal operation and external
interface, as a rule, switch on the external power supply after switching on the internal power supply.
When switching the power supply off, as a rule, switch off the external power supply and then the
internal power supply. Use of the reverse power on/off sequences may result in the application of an
overvoltage to the internal elements of the device, causing malfunction and degradation of internal
elements due to the passage of an abnormal current.
The correct power on/off sequence must be judged separately for each device and according to related
specifications governing the device.
6
INPUT OF SIGNAL DURING POWER OFF STATE
Do not input signals or an I/O pull-up power supply while the device is not powered. The current
injection that results from input of such a signal or I/O pull-up power supply may cause malfunction and
the abnormal current that passes in the device at this time may cause degradation of internal elements.
Input of signals during the power off state must be judged separately for each device and according to
related specifications governing the device.
Application Note U17209EJ1V0AN
3
These commodities, technology or software, must be exported in accordance
with the export administration regulations of the exporting country.
Diversion contrary to the law of that country is prohibited.
•
The information in this document is current as of July, 2004. The information is subject to change
without notice. For actual design-in, refer to the latest publications of NEC Electronics data sheets or
data books, etc., for the most up-to-date specifications of NEC Electronics products. Not all
products and/or types are available in every country. Please check with an NEC Electronics sales
representative for availability and additional information.
No part of this document may be copied or reproduced in any form or by any means without the prior
•
written consent of NEC Electronics. NEC Electronics assumes no responsibility for any errors that may
appear in this document.
•
NEC Electronics does not assume any liability for infringement of patents, copyrights or other intellectual
property rights of third parties by or arising from the use of NEC Electronics products listed in this document
or any other liability arising from the use of such products. No license, express, implied or otherwise, is
granted under any patents, copyrights or other intellectual property rights of NEC Electronics or others.
Descriptions of circuits, software and other related information in this document are provided for illustrative
•
purposes in semiconductor product operation and application examples. The incorporation of these
circuits, software and information in the design of a customer's equipment shall be done under the full
responsibility of the customer. NEC Electronics assumes no responsibility for any losses incurred by
customers or third parties arising from the use of these circuits, software and information.
•
While NEC Electronics endeavors to enhance the quality, reliability and safety of NEC Electronics products,
customers agree and acknowledge that the possibility of defects thereof cannot be eliminated entirely. To
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Electronics products, customers must incorporate sufficient safety measures in their design, such as
redundancy, fire-containment and anti-failure features.
•
NEC Electronics products are classified into the following three quality grades: "Standard", "Special" and
"Specific".
The "Specific" quality grade applies only to NEC Electronics products developed based on a customerdesignated "quality assurance program" for a specific application. The recommended applications of an NEC
Electronics product depend on its quality grade, as indicated below. Customers must check the quality grade of
each NEC Electronics product before using it in a particular application.
"Standard": Computers, office equipment, communications equipment, test and measurement equipment, audio
and visual equipment, home electronic appliances, machine tools, personal electronic equipment
and industrial robots.
systems, anti-crime systems, safety equipment and medical equipment (not specifically designed
for life support).
"Specific": Aircraft, aerospace equipment, submersible repeaters, nuclear reactor control systems, life
support systems and medical equipment for life support, etc.
The quality grade of NEC Electronics products is "Standard" unless otherwise expressly specified in NEC
Electronics data sheets or data books, etc. If customers wish to use NEC Electronics products in applications
not intended by NEC Electronics, they must contact an NEC Electronics sales representative in advance to
determine NEC Electronics' willingness to support a given application.
(Note)
(1) "NEC Electronics" as used in this statement means NEC Electronics Corporation and also includes its
majority-owned subsidiaries.
(2) "NEC Electronics products" means any product developed or manufactured by or for NEC Electronics (as
defined above).
M8E 0 2. 11-1
4
Application Note U17209EJ1V0AN
Regional Information
Some information contained in this document may vary from country to country. Before using any NEC
Electronics product in your application, pIease contact the NEC Electronics office in your country to
obtain a list of authorized representatives and distributors. They will verify:
•
Device availability
•
Ordering information
•
Product release schedule
•
Availability of related technical literature
•
Development environment specifications (for example, specifications for third-party tools and
components, host computers, power plugs, AC supply voltages, and so forth)
•
Network requirements
In addition, trademarks, registered trademarks, export restrictions, and other legal issues may also vary
from country to country.
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800-366-9782
N
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•
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•
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Novena Square, Singapore
Tel: 6253-8311
J04.1
Application Note U17209EJ1V0AN
5
INTRODUCTION
Target Readers This application note is intended for users who understand the functions of the
V850E/IA1, V850E/IA2, V850E/IA3, V850E/IA4, and V850E/MA3, and who design
application systems that use these microcontrollers. The applicable products are shown
below.
PurposeThe purpose of this application note is to help the user understand how a brushless DC
motor is controlled via the 120° sensorless drive excitation method that uses PWM
output and A/D converter input as a system example of the timer/counter function of the
V850E/IA1, V850E/IA2, V850E/IA3, V850E/IA4, and V850E/MA3.
OrganizationThis application note is divided into the following sections.
• Control method • Software configuration
• Hardware configuration • Program list
How to Use This ManualIt is assumed that the reader of this application note has general knowledge in the fields
of electrical engineering, logic circuits, and microcontrollers.
Cautions 1. Application examples in this manual are intended for the “standard”
quality models for general-purpose electronic systems. When using
an example in this manual for an application that requires the
“special” quality grade, evaluate each component and circuit to be
actually used to see if they satisfy the required quality standard.
2. To use this manual for special-grade products, read the part
Conventions Data significance: Higher digits on the left and lower digits on the right
Active low representation: xxx (overscore over pin or signal name)
Memory map address: Higher addresses on the top and lower addresses on
the bottom
Note: Footnote for item marked with Note in the text
Caution: Information requiring particular attention
Remark: Supplementary information
Numeric representation: Binary ... xxxx or xxxxB
Decimal ... xxxx
Hexadecimal ... xxxxH
Prefix indicating the power
of 2 (address space,
memory capacity): K (kilo): 2
M (mega): 2
G (giga): 2
4.5.14 Link directive file for V850E/MA3................................................................................................188
Application Note U17209EJ1V0AN
11
CHAPTER 1 CONTROL METHOD
1.1 Outline of Brushless DC Motor Control
A brushless DC (BLDC) motor consists of a stator, coil, and rotor. The rotor, which includes a permanent magnet,
is rotated by the action of the magnetic field generated by the coil of the stator.
The magnetic field is generated by exciting the coil wound around the stator in a specific sequence. By controlling
the intensity and cycle of the magnetic field with a microcontroller, the torque response and the number of revolutions
of the motor can be controlled.
This section explains how to control a BLDC motor without a sensor by using the V850E/IA1, V850E/IA2,
V850E/IA3, V850E/IA4, or V850E/MA3.
Figure 1-3 shows an example of the circuit of a three-phase brushless DC motor. The internal PWM output
function of the microcontroller is used to control the current that flows through the motor, by using a transistor array
consisting of six transistors.
The magnetic field is generated by controlling the excitation pattern of the six transistors as shown in Table 1-1.
Table 1-1. Excitation Pattern
Upper Arm Lower Arm Excitation
Pattern
<1> Active Inactive Inactive Inactive Active Inactive U → V
<2> Active Inactive Inactive Inactive Inactive Active U → W
<3> Inactive Active Inactive Inactive Inactive Active V → W
<4> Inactive Active Inactive Active Inactive Inactive V → U
<5> Inactive Inactive Active Active Inactive Inactive W → U
<6> Inactive Inactive Active Inactive Active Inactive W → V
U V W U V W
Excitation
Direction
12
Application Note U17209EJ1V0AN
CHAPTER 1 CONTROL METHOD
Figure 1-1. Three-Phase DC Motor Voltage Waveform
<1><2><3><4><5><6>
U phase
U phase
Driving voltage
waveform
V phase
V phase
W phase
W phase
U phase
Induced voltage
waveform
V phase
W phase
Application Note U17209EJ1V0AN
13
Magnetic
flux
CHAPTER 1 CONTROL METHOD
Figure 1-2. Rotor Position Detection Principle
CC
V
N
U
A
W-phase stator
is located in the
center of the N pole
and S pole of a
S
magnet rotor
S
V
CC
N
U
A
S
V
W
V
WC
N
(a) Rotor position <1> … U-phase stator: S pole
V-phase stator: N pole
W-phase stator: Center point
S
U
N
N
V
W
V
WC
A
V
CC
S
= 0
= 0
S
V
VC
= 0
V
W
N
(b) Rotor position <2> … U-phase stator: S pole
V-phase stator: Center point
W-phase stator: N pole
S
U
V
N
CC
V
N
W
S
V
UC
= 0
A
(d) Rotor position <4> … U-phase stator: N pole
V-phase stator: S pole
W-phase stator: Center point
S
U
N
V
VC
= 0
V
W
S
A
(e) Rotor position <5> … U-phase stator: N pole
V-phase stator: Center point
W-phase stator: S pole
14
(c) Rotor position <3> … U-phase stator: Center point
V-phase stator: S pole
W-phase stator: N pole
N
U
S
V
UC
= 0
Return to (a)
N
V
S
V
CC
A
W
N
V
CC
(f) Rotor position <6> … U-phase stator: Center point
V-phase stator: N pole
W-phase stator: S pole
Application Note U17209EJ1V0AN
CHAPTER 1 CONTROL METHOD
Figure 1-3. Configuration of Three-Phase Brushless DC Motor
TrU
TrU
1
TrV
1
OnOffOff
U
V
2
TrV
2
OffOnOff
PWM control
TrW
TrW
1
U
W
V
W
2
U
Zero-cross point detection
V
W
Application Note U17209EJ1V0AN
15
CHAPTER 1 CONTROL METHOD
The 120° control method for a BLDC motor without a sensor is described below.
To control a BLDC motor, the rotor position must be known.
To control a BLDC motor without a senso r, the rotor position is estimated using induced voltage.
The induced voltage is in phase with the driving voltage waveform and its waveform is close to a sine wave, as
shown in Figure 1-1. Figure 1-2 illustrates how the polarity of the stator of the motor is switched and how the magnet
rotor revolves.
As shown in Figures 1-1 and 1-2, a three-phase DC motor rotates its rotor by switching the three driving current
patterns on the three coil phases.
During period <1> in Figure 1-1, for example, transistor Tr U
1 in Figure 1-3 is turned on by the U-phase dr iving pin,
and TrV2 is turned on by the V-phase driving pin, causing the current to flow from the U-phase driving pin toward the Vphase driving pin. At this time, the W-phase coil seems to be disconnected from the driver circuit and induced voltage
is generated.
This induced voltage is used to detect the rotor position.
To control the number of revolutions of the motor, the voltage applied to the motor is controlled to change the
current flowing through the coil. To change the voltage, a waveform that is controlled by PWM is applied to the
transistor.
The voltage is changed by applying a waveform (PWM waveform) in proportion to the voltage to be applied, to the
transistors on the lower arm side (TrU
2, TrV2, and TrW2) while the transistors on the upper arm side (TrU1, TrV1, and
TrW1) are on.
16
Application Note U17209EJ1V0AN
CHAPTER 2 HARDWARE CONFIGURATI ON
This chapter describes the hardware configuration.
2.1 Configuration
The reference system’s main functions are described below. In this reference system, when the revolution
specification switch is pressed after power application, the motor starts revolving in the direction specified.
Figure 2-1. Overall System Configuration
Volume for
speed control
Driver IC
Reset circuit
Revolution
specification SW
LED display
3
13
A/D converter
RESET
Port
Timer
Microcontroller
WDT
6
V-U
V-V
V-W
Interrupt
Position
detection
Position
detection
Position
detection
M
Current voltage
conversion
Current voltage
conversion
V-U
V-V
V-W
Application Note U17209EJ1V0AN
17
CHAPTER 2 HARDWARE CONFIGURATION
(1) Volume for speed control
Volume for increasing and decreasing the number of revolutions of the motor
(2) Revolution specification SW
CW, CCW, and STOP switches
(3) LED display
LED displaying the number of revolutions, operation time, etc.
(4) WDT
Watchdog timer
(5) Driver IC
Driver for driving motor
(6) Current voltage converter
Converting the motor driving current to voltage, used for detecting overcurrent
(7) Position detector
Rotor position estimation signal output from the induced voltage
18
Application Note U17209EJ1V0AN
CHAPTER 2 HARDWARE CONFIGURATION
2.2 Circuit Diagram
Figures 2-2 to 2-6 show diagrams of the sample reference system circuit.
This sample reference system circuit diagram includes the V850E/IA1, V850E/IA2, V850E/IA3, V850E/IA4, or
V850E/MA3, a reset circuit, oscillator, a pin handling microcontroller peripheral block, operation mode switch block,
LED output block, watchdog timer circuit block, drive circuit block, motor controller, and motor revolution indicator.
(1) Microcontroller and microcontroller peripheral block
The V850E/IA1, V850E/IA2, V850E/IA3, V850E/IA4, or V850E/MA3 includes a reset circuit, an oscillator that
uses a resonator, and a block for handling the MODE pin and unused pins.
(2) Operation mode switch block
This includes switches that set the operation mode as CW or CCW operation.
(3) LED output block
This block includes 16 LEDs, which are used to indicate the revolution speed (rpm), errors, etc.
(4) Watchdog timer circuit block
This block uses the
V850E/IA3, V850E/IA4, or V850E/MA3 stops for one ms or longer.
(5) Drive circuit block
The 6-phase outputs from the inverter timer are converted to U-, V-, and W-phase output for the motor driver.
This drive circuit is not shown in detail in this example, since it varies depending on the motor’s specifications.
(6) Motor controller
This block includes the HPS-3-AS, LM324, and other devices that are used to measure the motor’s U and V
drive currents via A/D conversion.
(7) Motor rotation indicator
This block includes a volume adjuster and the LM324 for setting the motor’s revolution speed (rpm).
µ
PD74HC123A to output stop signals when pulse output from the V 850E/IA1, V850E/IA2,
Figure 3-1 shows a diagram of the software control block of the reference system.
Figure 3-1. Diagram of Software Control Block of Reference System
Control by microcontroller
<6>
A/D
conver-
<7>
Current
monitor
sion
A/D
conver-
sion
iu
iv
u
<3>
Speed
control
v
PWM
conver-
sion
Driver
circuit
<1>
Target
speed
(volume)
+
<2>
−
Speed
<5>
w
u, v, w
detection
<1> The volume is loaded by the A/D converter as a target speed.
<2> The speed to be calculated is determined by the difference from the present speed.
<3> Values of phases U, V, and W are set.
<4> The zero-cross point is detected by an induced voltage (by hardware).
<5> The speed is calculated by the interval of zero-cross point in each phase.
<6> An overcurrent is detected by the A/D converter.
<7> The speed is controlled by a current value.
Motor
<4>
External
zero-cross
point
detection
Application Note U17209EJ1V0AN
31
CHAPTER 3 SOFTWARE CONFIGURATION
3.2 Peripheral I/O
The following types of peripheral I/O functions are used in this reference system.