Automotive 1-KW 48-V BLDC Motor Drive Reference Design
Automotive 1-KW 48-V BLDC Motor Drive Reference Design
Automotive 1-KW 48-V BLDC Motor Drive Reference Design
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 1
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 2
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 4
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 5
48V
48V Protection
Protection
and
and Switching
Switching
12V
12V FET
FET
Flyback
Flyback Buck
Buck Gate
Gate
Protection
Protection Drive
Drive
Converter
Converter Regulator
Regulator Drivers
Drivers Stages
Stages
48V
Motor
Digital Current
Current
CAN
CAN Isolator Sense
Sense
Launch
Launch Pad
Pad
Temp
Temp
Sense
Sense
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 6
For more information on each device and why it was chosen for this application, see the following sections.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 7
The device has a maximum boot voltage of 120 V, allowing operation with the 48-V supply under all conditions
covered by the LV148 specification, including overvoltage conditions.
The device drives two N-channel FETs in high-side and low side (half-bridge) configurations, so that one device
can be used for each of the three BLDC motor phases.
The device has 3-A sink and 3-A source output current capability, suitable for rapid charging and discharging of
the gates of the drive stage FETs. The large output current means that the gate capacitance can be charged and
discharged in a small fraction of the PWM switching time, allowing high efficiency.
The device has rapid rise and fall time (8 ns rise, 7 ns fall with 1000-pF load) and precise (1 ns typical) delay
matching between rise and fall times. This means that a small dead-time is possible between the alternating
phases while still assuring no shoot-through current in the high-side and low-side FETs. This precision timing
allows maximum use of the PWM duty cycle with high efficiency.
An on-chip bootstrap diode eliminates the need for external discrete diodes.
Undervoltage lockout is provided for both the high-side and the low-side drivers, thus forcing the outputs low if
the drive voltage is below the specified threshold.
The device is qualified to AEC-Q100 temperature grade 1, which allows for operation in automotive applications
with a temperature range from –40°C to +140°C.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 8
This device has a wide input range (4.5 V to 52 V) which meets the requirements for the voltage range of the
automotive 12-V battery system.
The device is suitable for the flyback configuration with a grounded-source N-channel FET, which will be used to
supply the isolated secondary for biasing the components on the 48-V side of the design.
The device has a resistor-programmable oscillator frequency, which allows selection of the optimum switching
frequency up to 1 MHz.
The device incorporates current-mode control, which provides improved transient response and simplified loop
compensation.
The small package size (3 x 3 mm), internal slope compensation, and integrated low-side driver allow for a
compact solution.
The device is qualified to AEC-Q100 temperature grade 1, which allows for operation in automotive applications
with a temperature range from –40°C to +125°C.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 9
The device has an input voltage range from 4 V to 17 V, allowing significant variation of the secondary 12-V
supply coming from the flyback controller.
The device has a high switching frequency of 2.5 MHz (typical) which allows for the use of small inductors and
provides fast transient response, as well as high output-voltage accuracy by use of the DCS-Control topology.
This switching frequency is also well above the AM radio band, thus reducing EMI concerns.
The device has an internal current limit of 1 A, which protects against high-current faults, while providing the
necessary 3.3-V supply of about 250 mA (maximum) for the LaunchPad and ancillary control circuits.
The device is qualified to AEC-Q100 temperature grade 1, which allows for operation in automotive applications
with a temperature range from –40°C to +125°C.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 10
The device has a wide operating range (5.5 V to 65 V) and high absolute maximum rating (75 V) is suitable
for 48-V supply with tolerance variation.
The device has an adjustable undervoltage lockout (UVLO) which inhibits operation when 48-V supply is too
low.
The device is qualified to AEC-Q100 temperature grade 1, which allows for operation in automotive
applications with a temperature range from –40°C to +125°C.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 11
Satisfies the requirement for reverse-battery protection for automotive (12-V) electrical subsystems
Controls an external NFET in series with the battery supply input to act as an ideal diode, reducing voltage
drop and power loss as opposed to a discrete diode solution
Quickly turns off the external FET when a reverse-battery condition is detected, isolating and protecting
downstream circuitry
Has no ground reference, leading to virtually zero IQ operation. This helps the subsystem draw less standby
current from the battery. Many OEMs have very small IQ budgets.
Because the voltage drop across the FET is negligible; this provides more input voltage headroom, and thus
operation at low battery input voltages.
The device is qualified to AEC-Q100 temperature grade 1, which allows for operation in automotive
applications with a temperature range from –40°C to +125°C.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 12
This device meets the requirements of ISO 11898-2 and ISO 11898-5 for full compatibility with high-speed
CAN networks.
The device includes a SPLIT pin which provides a stable half-supply output voltage to stabilize the common-
mode voltage of the bus for improved electromagnetic emissions.
The device can be put into a low-power standby mode with very low standby current. Any valid CAN bus
activity can be detected by the RXD wake-up request, allowing activation of remote nodes by the master
node through CAN commands.
The device is qualified to AEC-Q100 temperature grade 1, which allows for operation in automotive
applications with a temperature range from –40°C to +125°C.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 13
The OPA365-Q1 and OPA2365-Q1 are similar; however, the OPA365-Q1 is a single op amp, and the
OPA2365-Q1 consists of two separate op amps in the same package.
These devices have gain-bandwidth (GBW) product of 50 MHz, which is suitable for amplification of the
current sense signals.
The devices have rail-to-rail operation, which allows more usable range for the analog-to-digital converters
(ADCs), giving better resolution of motor current measurements.
The devices have low input offset voltage (100 μV), which gives the current sense measurement low error.
The device is qualified to AEC-Q100 temperature grade 1, which allows for operation in automotive
applications with a temperature range from –40°C to +125°C.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 14
This device has a very accurate (±0.25°C) scale factor, which allows precise measurements of the board
temperature.
The devices are available in small SC70 package (2-mm x 2-mm) which facilitates placement close to the
motor phase driver stages, thus reducing thermal time delay.
A class-AB output structure gives the device strong output source and sink current capability that is well
suited to an ADC sample-and-hold input.
The device is qualified to AEC-Q100 temperature grade 0, which allows for operation in automotive
applications with a temperature range from –50°C to +150°C.
The layout concept locates the circuitry actively driving the motor within a circular area in the center of the board.
Connectors are outside the reference circle, and were selected for ease of use rather than suitability for a production
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 15
FETs
Phase B
Current Sense
CSD19535KTT
Resistor
FETs FETs
LaunchPad Connector
Phase A Phase B Phase C
J6
Current Sense
CSD19535KTT Gate Pre-Driver CSD19535KTT
Resistor
UCC27201A
Current Sense
Resistor
Analog Phase C
Phase A
Temperature Gate Pre-Driver
Gate Pre-Driver
Sensor UCC27201A
UCC27201A
LMT86-Q1
ESD
TPD4E001-Q1
Buck Converter
TPS62152-Q1
CAN
Connector Silkscreen Circle
48V Protection 3-Pin All Components
Secondary Winding
LM5060-Q1 J4 other than
Connectors Should
Digital Isolator be Located within
48V Filtering Flyback Transformer
750315511
Isolation ISO7331C Circle
CAN
Primary Auxilliary
Transceiver TOP Component
HVDA553-Q1
Flyback TOP or Bottom
CAN
Controller Component
Connector
TPS40210-Q1 2-Pin
J3
Capacitors are generally X7R grade (−55°C to +125°C) or higher, with size and value selected for the expected extremes
of operation conditions. The voltage rating of the capacitors should be greater than the maximum voltage they could
experience, and 2x the typical operating voltage to avoid DC bias effects. The amount of output capacitance used
depends on output ripple and transient response requirements, and many equations and tools are available online to
help estimate these values.
Consider the possible maximum voltage that could be experienced by the components. Capacitors should be derated by
a minimum of 25% due to the drop in capacitance at 100% rated DC voltage of X7R and C0G/NP0 ceramic capacitors
(that is, Max voltage – 40 V; Capacitor voltage rating = 40V * 1.25 = 50V). The derating also helps protect components
from unexpected voltage spikes in the system. During the design process the amount of BOM line items was considered.
Therefore, capacitor voltage ratings may have been increased above the minimum desired rating. As an example, if
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 16
Supplies in this solution were designed for a ±2.5% (5%) total transient response. Low-ESR ceramic capacitors were used
exclusively to reduce ripple. For internally compensated supplies, see device-specific data sheets, because they may
have limitations on acceptable LC output filter values.
For improved accuracy, all feedback resistor dividers should use components with 1% or better tolerance. Resistance
tolerance in this design was selected to reduce the total amount of BOM line items. In the design considerations, it is
noted where 5% or 10% precision resistors can be used to reduce the cost of a specific individual resistor. Using less
precise resistors for cost reasons should be weighed against reducing the amount of BOM line items and ordering in
higher volumes to reduce total BOM cost.
Zero-Ohm (0-Ω) resistors are used at the input and output of several of the circuit sections for testing purposes only, and
could be removed, if needed, in a production board design.
The diode breakdown voltages should be chosen such that transients are clamped at voltages which will protect the rest
of the system, but not conduct during normal operational input voltages. The positive clamping device should clamp
above double-battery (jump-start) and clamped load dump voltages, but lower than the maximum operating voltage of
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 17
The reverse clamping device should clamp all negative voltages greater than the battery voltage so that the device does
not short out during a reverse-battery condition.
Due to the energy of the pulses, SMB size TVS diodes with 600-W instantaneous peak power ratings are the minimum
required.
The SMBJ28A-13F is specified for peak current of 13 A, with breakdown from 31.1 V to 45.4 V.
The SMBJ14A-13F is specified for peak current of 25 A, with breakdown from 15.6 V to 23.2 V.
Both diodes have an operating temperature range of –55 to +150°C, with peak power of 600 W.
Rather than use the traditional diode rectifier solution for reverse battery protection, this implementation uses an N-
channel MOSFET driven by the LM74610-Q1 Smart Diode Controller. The power dissipation of the traditional diode can
be significant due to the typically 600-mV to 700-mV forward drop (P = I*V), whereas using the LM74610 solution results
only in the loss due to the RDS(ON) of the FET; this loss can be significantly lower, resulting in greater efficiency and less
thermal dissipation required.
The LM74610 team provides recommendations, as well as a tool, which can be used to help select a FET for any specific
application. Here are the important considerations:
• Ensure that the continuous current rating is sufficient for the application.
• The VGS threshold should be not more than 2.5 V.
• VSD should be at least 0.48 V @ 2 A and 125°C.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 18
Due to flexion of the printed-circuit board (PCB), a ceramic capacitor can mechanically fail in an electrically shorted
condition. If this happens to an input capacitor connected directly to the battery, this could cause a hard short at the
battery terminals. To avoid this, typically two ceramic capacitors are used in series; if one fails, there is still another to
avoid a short. The capacitors should also be aligned at 90 degrees with respect to each other on the layout; this gives a
good chance that a flexion in one direction may only affect the capacitor aligned in that direction, but not the capacitor
in the other direction.
In general, the optimal amount of capacitance on the output side of the 12-V filtering may depend on the specifics of the
application, including the current and electromagnetic compatibility (EMC) considerations. In this design, two large
electrolytic capacitors (C5 and C6) are available for installation; the selection of one or both capacitors gives designers
flexibility. In the testing which follows, C5 was installed and C6 was not installed.
Buck 3.3V_B
5V_A
Figure 15 Power Supply Scheme
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 19
The switching frequency is set by C63, C64, and R40 to a nominal 450-kHz rate, which is below the lowest frequency in
the AM radio band.
DIS/EN signal on pin 3 has an internal 1-MΩ pulldown resistor to GND. Leaving the pin open, or connected to ground,
will enable the device. In this design a 10-kΩ resistor (R43) is used with a test point (DIS_FLYBACK) so that the device
can be set to shutdown mode by overriding the 1-MΩ pull-down with an external signal.
R34 dissipates power linked to leakage energy and C54 ensures low-voltage ripple. C54 could be a 50-V capacitor but a
100-V capacitor was chosen to reduce the amount of BOM line items. Similarly, C63 can be a 50-V capacitor but a 100-V
capacitor was chosen to reduce the amount of BOM line items.
The 0-Ωresistor R47 is available to provide a disconnect between the 5 V generated by the flyback and the rest of the
system that is powered by the 5-V flyback auxiliary winding. This will not disconnect the 5 V from the feedback for the
flyback controller. This allows unloaded testing if required. Specific load simulations can be accomplished by not
populating R47 and by populating R49 with the appropriate load resistance.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 20
The secondary 12-V supply (12V_B) is not directly regulated by the TPS40210-Q1, but is indirectly regulated through the
coupling to the 5-V primary winding (5V_A). Precise regulation is not needed for the 12V_B supply, because the
UCC27201A gate drivers tolerate a wide input voltage for their bias supply, and because the signal conditioning
components in the feedback paths (which do require tight regulation) are supplied by a 3.3-V supply from the buck
regulator discussed in the next section.
The RC (C58, R37) snubber across D7 can be used to dampen parasitic oscillations. High-frequency ringing can be due to
parasitic inductance of the transformer and parasitic capacitance of the diode.
The TPS62152-Q1 provides a small and efficient solution, with a minimum of external components. The TPS62152-Q1
operates at a switching frequency of 2.5 MHz, well above the AM band, when the FSW pin is tied to ground. The
maximum input voltage of 17 V provides sufficient headroom above the 12-V nominal value to allow significant variation
from the flyback converter. The 1 A maximum output current is sufficient for the expected load of LaunchPad plus op
amps and temperature sensors.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 21
One 10 μF input capacitor is recommended. However, additional capacitance can be added to reduce input current
ripple further. Thus, C29 and C30 are installed in the design, but can be altered if a reduced size or cost solution is to be
investigated.
Similarly, TI recommends using one output capacitor, but an additional can be added to help with load transients. Thus ,
C27 and C28 are installed in the design, and provide flexibility for designers to evaluate possible reduced solutions.
Only 25-V capacitors are needed but 50-V capacitors were chosen to reduce the amount of BOM line items. R12 does
not need to be a 1% resistor, but it was chosen to reduce BOM line items.
The output voltage is fixed at 3.3 V, therefore FB pin is tied to GND plane to improve thermal performance.
To disable the buck converter, remove R12 and deliver an external signal through EN_3V3. To re-enable the buck,
connect from test point 12V_B to test point EN_3V3.
A macro model of the TPS62152 is available for circuit performance simulation using Texas Instruments’ TINA or other
SPICE-based circuit analysis tools. Figure 19 shows a transient analysis of the initial turn-on of the 12-V to 3.3-V buck
circuit, with a 33-Ω load, giving a final load current of 100 mA. The start-up transients have stabilized after less than 2
milliseconds.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 22
The pi filter arrangement shown in Figure 20 blocks the unwanted high frequencies while passing the desired stead-state
current. Due to the high current levels anticipated, these components (especially L2, C16, and C17) are physically large,
as discussed in the section on board layout.
Both the 48V_BATT_B and 48V_FILTERED_B rails must withstand a maximum voltage of 70 V (per LV148). Therefore,
the summation of capacitors in series could equal 87.5 V by applying a 25% margin on 70-V max voltage.
The voltage ratings of the series output capacitors C18 and C19 are higher than necessary, but were selected to reduce
the number of BOM line items.
Due to the maximum current of 30A and worst-case RDS(ON) of a single FET, the power dissipation would cause the
temperature rise to be too significant. By using two FETs in parallel (Q2 and Q10), the total RDS(ON) is reduced by half
which reduces the power dissipation and, in turn, reduces the temperature rise.
The resistor divider formed by R4, R8, and R11 sets the levels at which the UVLO and overvoltage lockout (OVLO)
activate. This prevents possible damage or poor performance when the 48-V supply is outside the desired range.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 23
The values of R4, R8, and R11 set the undervoltage and overvoltage thresholds such that:
• Q2 and Q10 are off for values of 48V_FILTERED_B less than 19 V (UVLO)
• Q2 and Q10 are disabled when 48V_FILTERED_B increases above 67 V (OVLO set)
• Q2 and Q10 are re-enabled when 48V_FILTERED_B decreases below 59 V (OVLO reset)
A timer capacitor (C25) allows a finite amount of time for the gate to charge and the output voltage to rise during start-
up before indicating a fault condition.
The indicator LED5 is illuminated when the 48 V is correctly switched to provide supply to the motor drive circuit. When
the external MOSFET VDS decreases such that the OUT pin voltage exceeds the SENSE pin voltage, the nPGD indicator is
active (low = no fault) and LED5 is illuminated. There is a 16-μA current sink on the SENSE pin, and an 8-μA current sink
on the OUT pin, so resistors R5 and R10 affect the relative measurements of the voltages across the MOSFET drain-to-
source.
The high-side and low-side gate driver (U10) receives PWM signals from the microcontroller and generates the
corresponding level-shifted (higher amplitude) signals to drive the gates of the high-side MOSFET (Q4) and low-side
MOSFET (Q5). U10 is biased by the 12V_B supply, with allowable supply tolerance from 8 V to 17 V.
The PWM switching frequency can range from 15 kHz to 50 kHz. This frequency is set by the parameters of the
MotorWare software running on the LaunchPad microcontroller board.
Resistors R55 and R58 reduce the turnon slew rate for the transistors, and can be adjusted if faster switching or lower
emissions are required. Diodes D9 and D12 bypass those resistors to speed up the transistor turnoff transitions, thus
reducing the possibility of shoot-through current.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 24
Several components (R56,D11, R54, C73, D10, R59, D14, C77, D13, and R57) around the high-side and low-side drive
transistors can be used to tune the circuit for best performance in terms of switching transition time, overshoot and
ringing during switching, and conducted and/or radiated emissions. In general, the specific values will depend on the
motor being driven and the application parameters such as speed, torque, and so forth.
TVS diodes (D11, D14) across the gate to source nodes protect the MOSFETs gate in the event of overvoltage transients.
The RCD clamps across each FET (R54, C73, D10 and R57, C77, D13) clamp the positive ringing drain to source and avoid
the FET being pushed in avalanche condition. The RC circuit values may require tuning.
The low-side current through phase A flows through R61, giving a scale factor of 1 mV per amp. Optional low-pass
filtering is provided by R60, R62, C78, C79, and C80 with differential symmetry maintained with equal values of R60 and
R62, and C78 equal to C80.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 25
Low-pass filtering can be accomplished by selecting C43 to reduce the amplifier gain at high frequencies. However, if
the filter time constant is longer than the shortest PWM pulse, the current measurement will be affected.
Note: For the following test results, C43, C78, and C80 are not installed, and the value of
C79 is 1 nF.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 26
The RC time constant formed by C85 and R80 give a low-pass filter with corner frequency 318 Hz. This frequency allows
all expected motor drive voltage waveforms to pass (318 Hz is 19 kRPM) while averaging the PWM switching pulses and
filtering out higher frequency noise.
A macro model of the OPA2365A is available for circuit performance simulation using Texas Instruments’ TINA or other
SPICE-based circuit analysis tools. Figure 25 shows a frequency transfer function analysis of the motor voltage feedback
circuit. As expected, the low-frequency gain is –26.4 dB (corresponding to an attenuation of 21:1), and the first low-
frequency corner frequency is approximately 300 Hz.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 27
The scale factor from the LMT86 is –10.9 mV/°C with a range of –50°C to +150°C, covering an output range of 0.4 V to
2.6 V, which is within the input voltage range of the ADC. Due to the integrated features of the LMT86-Q1, very few
external components are needed.
The 1-kΩresistors (R64-R72) allow connection to sensors with push-pull, or open-collector outputs with either pullup or
pulldown biasing. In all cases, the resistor values can be changed to provide any signal attenuated needed to adjust
signals with higher voltage levels to match the 3.3-V signal levels expected at the interface to the LaunchPad
microcontroller board.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 28
The C2000 Piccolo™ LaunchPad evaluation kit, based on the F28027 microcontroller (MCU), is a modular, quick-launch
evaluation kit that contains everything needed – device, emulation and software – to explore the latest digital control
techniques in areas such as power, lighting, and motor control.
The 40 pins on the LaunchPad headers allow for easy access to all the peripherals on the F28027x device. These pins
enable modularity by supporting 20-pin and 40-pin BoosterPack™ modules such as motor drive inverters, LED lighting,
and much more. The TIDA-00281 board is designed with two corresponding 20-pin headers (J5 and J6) to interface with
the LaunchPad pins.
The TIDA-00281 supplies 3.3-V power (and ground) to the LaunchPad through the standard header pins. The
programing emulator and USB connection on the LaunchPad is isolated from the 3.3-V power supplied by the TIDA-
00281 board (with LaunchPad jumpers JP1, JP2, and JP3 removed).
Figure 28 shows the connections on J5 (20-pin connector) and J9 (3-pin connector). The pin assignments are in
accordance with the BoosterPack standard, allowing connection to various LaunchPad boards. All signals are referenced
to the 3.3-V supply derived from the secondary of the flyback converter.
The PWM signals are generated by the microcontroller, and connect with the UCC27201A-Q1 gate drivers. The HALL
signals come from the motor position sensors, and connect to the microcontroller for sensored commutation. The
48V_BUS_EN signal comes from the microcontroller, and enables the 48-V supply to the motor drive circuits.
Figure 29 shows the connections on the J6 (20-pin connector) to the LaunchPad board. The feedback signals (voltage,
current, and temperature) are filtered by the RC components, with a low-pass corner frequency of 1.4 MHz to reduce
high-frequency noise. These filter components can be modified if designers find specific noise frequencies which must
be attenuated.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 29
The logic signals CAN_TX and CAN_RX and CAN_STB are connected to 3-pin header J4, allowing connection to signals
from a CAN-enabled microcontroller. These signals are referenced to the 3.3V_B ground, which is derived from the 12-V
supply from the flyback converter secondary.
Various schemes are implemented by different automotive manufacturers to provide transient voltage protection and
EMC performance on CAN networks. The common-mode choke (L4) and protection diodes (D4 and D5) give designers
flexibility in how to implement the protection for this CAN circuit.
Use termination resistors (R15 and R17) if this board is used as one of the two terminating nodes in a CAN network,
otherwise remove these resistors.
System requirements determine the bias capacitors needed on digital isolator (U6). The device will work in many
applications with only a single 0.1-μF capacitor (C36, C37) on both VCC1 and VCC2. Additional capacitors C34, C35, C38,
C39 are provided for flexibility in design.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 30
D4 should not be installed between the transceiver and the choke unless inductive flyback transients occur from
common-mode choke. TVS diodes should, in a typical scenario, be installed closest to the connector as shown by the
location of D5. See Figure 30.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 31
Use caution when mounting the LaunchPad to the TIDA-00281 board, as misalignment
of the header pins during installation may cause damage.
Note that the TIDA-00281 board is designed to allow mounting the LaunchPad board either on the top side (preferred)
or the bottom side (optional). If mounted on the top side, the LaunchPad indicator LEDs will be easily visible, and the
push-button switches will be easily accessible.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 32
There are additional switches on the Launchpad which must be set correctly; S1 (boot mode selection) and S4 (serial
connectivity select).
The LaunchPad's microcontroller includes a boot ROM that performs some basic start-up checks and
allows for the device to boot in many different ways. S1 has been provided to allow users to easily configure the pins
that the bootROM checks to make this decision whether to perform an emulation boot or a boot to flash. In general all
3 switches on S1 should be in the ON position. More information about boot mode selection can be found in the
TMS320x2802x Piccolo Boot ROM Reference Guide (SPRUFN6).
When S4 is in the up (ON) position, the Piccolo device's SCI is connected to the XDS100 and users are able to receive and
send serial information from or to the board via the USB connection. When S4 is in the down position, the Piccolo
device's SCI is disconnected from the XDS100 and BoosterPacks.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 33
The TIDA-00281 board and connected LaunchPad board was tested using Texas Instruments’ MotorWare software, with
some additional files necessary to adapt to the specific hardware configuration of the TIDA-00281 board.
MotorWare is the software infrastructure and distribution mechanism for the InstaSPIN-FOC and InstaSPIN-MOTION
motor control solutions. It includes source code object oriented APIs for peripheral drivers and modules (including a
freshly updated set of motor control functions). These APIs are used to build multiple InstaSPIN-FOC projects that
demonstrate the different modes and capability, documented through the Projects and Lab User’s Guide.
The MotorWare software can be downloaded from the Texas Instruments web site at
http://www.ti.com/tool/MOTORWARE . Follow the installation instructions to install on your local computer.
After installation of the MotorWare software, follow the steps below to add the files necessary to use MotorWare with
the TIDA-00281 board. Note that version 14 of MotorWare was used during testing; if a newer version of MotorWare is
used, replace the “14” in the steps below with the appropriate corresponding version number.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 35
Step 1: Import the existing project, for example proj_lab02b, from the motorware directory. In this instance, there are
two projects in the directory.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 36
Note that this design will work with other projects in the MotorWare libraries, but lab02b has all the features needed to
exercise the design as documented in this report.
The connection will depend on the JTAG emulator you use. For the LAUNCHXL-F28027F LaunchPad, the XDS 100
v2 emulator should be selected from the “Connection” pull-down menu. The target device on this board is the
TMS320F28027 piccolo microcontroller. After selecting the connection and target device, save the configuration set-up
by clicking the “Save” button.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 37
Make sure the project is active by clicking on the project name (for example proj_lab02b) in the Project Explorer
window. Build the project by clicking the hammer icon on the CCS Edit toolbar. If the project builds correctly, the
message “Build Finished” will display at the end of the text in the Console window. See Figure 39.
Note, in case of errors during build or execution, there may be states where the project
build encounters problems due to previous build and/or execution. Performing a
“Clean” build (select Clean under the Project menu) will rebuild the project from a
completely reset state.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 39
Step 8a: Set the Flag_enableSys to 1 by clicking in the value field and entering a 1.
At this point the operation of the system can be verified by observing that the 48V supply voltage is correctly being
monitored. Change the expression VdcBus_kV to Q-Value(24) by right-clicking in the Value field, then selecting Q-values
and “24”. Verify that the value for VdcBus_kV corresponds to the DC supply voltage. In this case (Figure 40), the supply
voltage is 48.8V.
Step 8b: Set the Flag_Run_Identify to 1 by clicking in the value field and entering a 1.
The motor will be driven with small and large motions, drawing up to several Amps. After about a minute, the
Flag_MotorIdentified is set to 1 by the controller. This indicates the motor has been successfully identified for
sensorless operation.
Step 9: When the motor has been successfully identified, the Flag_Run_Identify will be reset to 0. At this point, again set
the Flag_Run_Identify to 1 by clicking in the value field and entering a 1. This will allow the system to operate with the
motor parameters already determined. After a moment, the motor will begin to spin at the speed set by the
SpeedRef_krpm parameter value.
Step 10: To change the commanded speed, click on the value field of SpeedRef_krpm and enter a new value (in kRPM).
To change the acceleration, click on the value field of MaxAccel_krpmps and enter a new value (in kRPM per second).
Note that the speed reference can be either positive or negative, affecting whether the motor rotation is clockwise or
counterclockwise.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 40
The reverse-battery performance is shown in Figure 42. Note that at about 17V, the Zener diode D2 begins to conduct,
and the reverse current increases. Refer to Figure 12 and Figure 13 for the electrical schematics for this circuit.
The curves in Figure 43 show that the 12V-to-12V efficiency is greater than 70% for output currents greater than 50 mA
when the input voltage is at the nominal 12V level. Note that for these curves, the 5V supply on the primary side of the
winding was loaded with a 4kOhm resistor. This would be a lightly loaded condition for the 5V supply, with only about
1.25 mA of current.
The curves in Figure 44 show the efficiency when the 5V supply on the primary side of the winding is loaded with a 100
Ohm resistor. This would be a typical loaded condition for the 5V supply, with about 50 mA of current for the CAN
transceiver and digital isolators. Note that for these curves, the 12V-to-12V efficiency is greater than 60% for output
currents greater than 60 mA when the input voltage is at the nominal 12V level.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 42
Figure 45 Combined efficiency, 12V flyback and 3.3V buck with 100 Ohm load on 5V supply
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 43
In the following oscilloscope plots, channel 1 (yellow) is connected to 48V_BUS_EN on U2-5, the enable pin for
LM5060Q1 high-side controller. Channel 2 (purple) is connected to 48V_BATT_B the 48V input, and channel 3 (blue) is
connected to 48V_MOTOR_B, which supplies the motor drive stages.
Figure 46 shows the voltages when the 48V supply to the motor drives is enabled by the microcontroller. There is about
4 milliseconds of delay between the 48V_BUS_EN signal going high and when the 48V_MOTOR_B supply is applied to
the drive circuits. A slight dip in the 48V input voltage is also noticeable; this is due to the charging current for the
capacitors connected to the 48V_MOTOR_B supply.
Figure 46 Switching sequence for enabling the 48V supply Figure 47 Switching sequence for disabling the 48V supply
Figure 47 shows the voltages when the 48V supply to the motor drives is disabled by the microcontroller. After a brief
delay, the 48V_MOTOR_B supply begins to discharge. During this test, no motor load was applied, so the discharge
takes about 150 milliseconds to reach relatively low voltage levels.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 44
The dynamometer used during this testing was the Magtrol model HD-705-6N, which is rated for 300W continuous
operation, with maximum power up to 1400W for short periods. It is capable of rotation up to 25000 RPM, and can
apply up to 55 in-lb (6.2 N-m) of torque. The dynamometer controller was a Magtrol model DSP6001, which can be
controlled manually or using the M-TEST software through a serial link to an external computer.
Figure 49 shows one of several user interface screens available in the M-TEST software to set the dynamometer. Later
figures will show M-TEST screens which display various dynamometer measurements, including rotational speed,
applied load torque (also called dynamometer braking) and power delivered to the load (dynamometer).
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 45
7.2.2 Motor no-load speed and current versus 48V supply voltage
The 48V automotive battery supply can be expected to vary in real-world applications. This design should maintain
control of the motor over a range of at least 36V to 60V, but the motor drive performance is affected by the supply
voltage.
• At any given supply voltage, the current required to maintain a specific speed will vary more or less directly with
the speed.
• Assuming constant load, the maximum attainable speed will increase as the applied supply voltage increases.
• At any given speed, the motor current will vary inversely with the applied voltage, assuming a constant load.
The plots in Figure 50 show these relationships for the BLY344S motor. Note that these measurements were with no
dynamometer attached. The maximum no-load speed for each supply voltage is indicated by the endpoint of the
corresponding line.
Unless otherwise specified in later sections, the motor supply for all remaining measurements was set to the nominal
value of 48V.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 46
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 47
180
160
140
120
Efficiency (%)
Power (W)
100
80
60
P48
40 Pdyna
20
0 0
0 500 1000 1500 2000 2500 3000
Motor Speed (RPM)
Another view of the system performance is the operation with varying torque loads at constant speed. As discussed in
later sections, there is a transient speed error when the torque load instantaneously changes. The actual speed then
returns to the commanded speed, with motor current proportional to the total torque. Figure 52 shows the electrical
power from the 48V supply and the mechanical power measured by the dynamometer as the brake load is varied. The
commanded speed was constant at 3000 RPM. Note that even with zero commanded brake load, there is some
(approximately 6.5W) of parasitic torque load measured by the dynamometer. Similarly, there is about 30W of electrical
power provided by the 48V supply. As the controlled load torque is increased, both the measured dynamometer power
and electrical power increase fairly linearly.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 48
120 70
100 60
Efficiency (%)
Power (W)
80 50
60 40
P48
40 Pdy 30
Efficiency
20 20
0 10
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35
Dynamometer Brake Load (N-m)
The effect of changing both motor speed and applied brake load is illustrated in Figure 53. Note that (as above) there is
a small (e.g.125 mA) electrical current from the 48V supply, even at low speed and negligible load. The supply current
(and thus electrical power) increases linearly as the speed increases, and also increases proportionally as the applied
brake load is increased.
4
3.5 No brake
0.2 Nm brake
3 0.5 Nm brake
48V supply current (A)
2.5
1.5
0.5
0
0 500 1000 1500 2000 2500 3000 3500
Motor Speed (RPM)
Figure 53 Power supply current vs. motor speed and dynamometer brake load
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 49
In the following oscilloscope plots, signal traces are captured at four points along a single phase of the motor drive
circuit. Channel 1 (yellow) is the high-side PWM signal (PWM_AH) from the Launchpad microcontroller to the
UCC27201A-Q1 gate drive chip. Channel 2 (pink) is the voltage at the gate of the high-side FET (GATE_DRIVE_AH).
Channel 3 (blue) is the motor phase voltage (A_PHASE). Channel 4 (green) is the current feedback signal after
amplification by a gain of 20 V/V, giving it a scale factor of 20mV/A (IA_FB).
In each of the following plots, note that the current feedback signal (Channel 4; green) is synchronously sampled by the
microcontroller during the time that the low-side drive FET is turned-on. This is when the corresponding high-side drive
FET is switched off; that is, when the signal on Channels 1 and 2 is low.
Figure 54 Motor speed 1000 RPM, no load, minimal 48V Figure 55 Motor speed 1000 RPM, 20% brake load (0.283 N-
current (180 mA) m), negative current, 48V current is 0.87A
In Figure 54, the PWM signals (Channels 1, 2,and 3) are As the motor current increases, the green signal on
synchronized, and no significant delay is observable as the Channel 4 shows a departure from the 1.65V “quiescent”
high-side signal propagates through the component chain. point. Note that when the high-side PWM signal is high,
Channel 4 (green, IA_FB) shows the current has transients the high-side FET is turned on, and there is no current
during the PWM switch points, but otherwise is relatively through the low-side FET. Thus the current feedback
stable around the 1.65V offset (half of the 3.3V supply). signal is at the 1.65V quiescent point when the high-side is
This allows the effectively “zero” current to be centered in active. When the high-side signals are low, the low-side
the middle of the usable range of the 3.3V analog-to- FET is on, and the current through the sense resistor is
digital converters on the LaunchPad. negative (in this case), thus the current feedback signal is
less than 1.65V.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 50
in Figure 56, the motor speed and overall current are the The horizontal time scale has been lengthened to 200
same as the previous figure, but in this case the signal on microseconds per division in Figure 59. Although the
Channel 4 indicates positive current going through the PWM signals are less distinct, the current feedback signal
sense resistor. The IA_FB signal is still at the 1.65V on the green channel shows the time-varying
quiescent point when the PWM signals are high, but is characteristics as the current through this phase changes
higher than 1.65V when the PWM signals are low. Thus a with the motor angular position. Again note that during
positive phase A motor current is fed back and sampled by the time when the high-side FET for phase A is active,
the real-time microcontroller on the LaunchPad. there is no current through the corresponding low-side
FET, thus the feedback signal is at the 1.65V quiescent
position during part of each PWM period.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 51
Figure 61 Envelope of motor phase current feedback signal, Figure 64 Envelope of motor phase current feedback signal,
1200 RPM, 0.5 N-m load 1200 RPM, 1.3 N-m load
Figure 62 Envelope of motor phase current feedback signal, Figure 65 Envelope of motor phase current feedback signal,
1200 RPM, 0.8 N-m load 1200 RPM, 1.4 N-m load
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 52
600
500
Electrical Power (W)
300
200
100
0
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Load torque (N-m)
Figure 66 Summary of current feedback measurement results
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 53
Figure 67 Phase voltages, 1000 RPM, No load Figure 69 Phase voltages, 1000 RPM, 30% brake
Figure 68 Phase voltages, 1000 RPM, 20% brake Figure 70 Phase voltages, 1000 RPM, no brake
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 54
In addition to the PWM signals and motor phase voltages, the feedback signal to the microcontroller is also of interest.
The motor commutation algorithm and control loops require information on the present voltage on each of the motor
phase windings. The motor phase current is filtered and scaled to fit the 3.3V analog-to-digital converter (ADC) inputs
on the C2000, providing a feedback signal for the digital control loop.
In Figure 73 through Figure 81, these signals are captured on oscilloscope plots under various operating conditions.
Channel 1 (yellow) is the PWM signal from the C2000 to the UCC27201 high-side gate driver input (PWM_AH).
Channel 2 (pink) is the corresponding output from the UCC27201 to the phase A high-side FET gate (GATE_DRIVE_AH).
Channel 3 (blue) is the voltage at motor phase A (A_PHASE).
Channel 4 (green) is the filtered, shifted, scaled version of the phase signal that is fed back to the C2000 ADC. (VA_FB).
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 55
Figure 73 Motor speed 2400 RPM, no load, phase Figure 75 PWM_AH, GATE_DRIVE_AH, A_PHASE
A duty cycle < 50% and VA_FB with motor speed 3000 RPM, no load,
showing Phase A average voltage repeating with a
5 ms period (4 pole-pair motor)
In Figure 73, the PWM signal from the
microcontroller is high about 25% of the time;
Figure 75 has a longer time scale, such that the
this is reflected in Channels 1, 2 and 3. Channel
individual PWM pulses are no longer distinct on
4 is a filtered version, scaled for the ADC, and
Channels 1, 2 and 3. At this scale, the sinusoidal
represents the average (filtered) version of the
variation in the filtered feedback signal (VA_FB
PWM phase voltage, about 500 mV.
on Channel 4) can be observed. The peak-to-
peak amplitude of the feedback signal is about
2V, which fits well with the 3.3V range of the
C2000 ADCs.
Figure 77 Phase voltage feedback signals, 1000 Figure 79 Phase voltage signals, 2500 RPM, 0.3 N-
RPM, 126W (1.2 N-m) load, 225W electrical power m load, 84W @ dyno, 107W electrical power
Figure 78 Phase voltage feedback signals, 1000 Figure 80 Phase voltage signals, 2500 RPM, 0.19
RPM, 147W (1.x N-m) load, 324W electrical power N-m load, 50W @ dyno, 68W electrical power
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 57
Figure 82 Speed ramp increase from 300 RPM to 600 RPM Figure 84 Speed ramp from 200 RPM to 2000 RPM @ 200
@ 200 RPM/sec, no brake RPM/sec, 0.33 Nm load (77W)
Figure 86 Speed ramp increase from 200 RPM to 2200 Figure 88 RP34-313, speed increase from 200 RPM to 2200
RPM @ 500 RPM/sec, 0.32 Nm load RPM @ 500 RPM/sec, no brake
This trend continues in Figure 87, in which the In Figure 88 and Figure 89, the effect of reducing the
acceleration has been increased to 1000 RPM/second. load torque is illustrated. In these figures, the
The speed overshoot has increased to about 50 RPM, dynamometer brake was disabled. The maximum
which is 2.5% of the commanded increase in speed. overshoot in speed is about 50 RPM, which is very
comparable to the overshoot with 0.32 Nm.
The following figures (Figure 90 - Figure 93) show additional examples of increases and decreases in the commanded
speed of the motor. In these figures, the speed error is a function of the motor and load characteristics, as well as the
parameters set in the control software. For more information, see the labs on motor control in the MotorWare software
package.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 59
Figure 90 RP34-313, speed decrease from 2200 RPM to Figure 92 Speed response, RP34-313, 48V, 14% brake load
200 RPM @ 500 RPM/sec, no brake
Figure 91 Detail of speed decrease showing overshoot in Figure 93 Speed response, RP34-313, 48V, 14% brake
speed response load, detail showing overshoot in speed response
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 60
top (black) trace. In this figure, the vertical grid lines represent 100 samples (600 ms @ 6ms/sample) so the torque step
transition takes about 300 ms.
The second (red) trace shows the speed of the tachometer, which is firmly coupled to the BLDC motor. From the initial
1000 RPM, the speed momentarily decreases when the braking torque step is applied. In this case, a peak speed error
of about 30% is evident. The motor speed returns to the commanded 1000 RPM after about 500 milliseconds.
The third (green) trace shows the power measured at the tachometer, and is the product of the measured torque and
rotational speed. Note that with the 1.36 N-m load applied at 1000 RPM, the power delivered to the tachometer is
about 143 Watts.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 61
Figure 95 Response to decrease then increase in load torque, 1000 RPM, 150W to no brake then 90W load
Note that in Figure 95 the maximum speed error during the decrease in load torque is about 45%, and the maximum
speed error during the increase in load torque is about 20%, corresponding to the amplitude change of the load torque.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 62
Figure 96 Repeated torque steps between 0.25 N-m and 0.55 N-m, with motor speed 2100 RPM
In Figure 96 the load torque applied by the dynamometer is repetitively cycled between 0.25 N-m and 0.55 N-m, with
the motor commanded to a constant 2100 RPM speed. This represents a load power that alternates between about
55W and 125W. As the load varies in a stepwise fashion, the speed changes from the set-point of 2100 RPM and then
recovers as the control loop compensates for the change in load.
The dead-time on the rising and falling edges of the PWM signal can be independently set, by altering the code in the
hardware abstraction layer file, hal.h, as shown in Figure 97 below. Note that the unit of time is system clock periods,
which for the TMS320F28027F LaunchPad is 16.7 nanoseconds (the reciprocal of the 60 MHz system clock frequency).
Integer multiples of the clock period are valid settings for these parameters.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 63
Figure 97 Code fragment in hal.h, allowing setting the PWM dead-time parameters
In part due to the precise timing specifications of the UCC27201A-Q1, the dead-time for this design can be reduced
below the default value of 4 system clock cycles (67 nanoseconds). Figure 98 and Figure 99 show the two PWM signals
associated with motor phase A, and illustrate the adjustability of the dead-time parameter, in this case for the falling
edge. Note that in both plots, the measured dead-time between transitions is as expected.
Figure 98 PWM phase A HI (yellow) and low (pink) Figure 99 PWM phase A HI (yellow) and low (pink)
with deadband = 4 with deadband = 1
Figure 100 and Figure 101 show the effect of changing the dead-time parameter on the waveforms of the motor drive
stage. In these oscilloscope plots, channel 1 (yellow) is the gate drive signal from the UCC27201A-Q1 to the high-side
FET gate, and channel 2 (pink) is the gate drive signal to the low-side FET. Although it is difficult to discern the initiation
of the rising edge due to the shape of the waveform, it is evident that even with only 1 system clock period of dead-
time, there is no overlap in the high-side FET and low-side FET “on” times.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 64
Figure 100 PWM signal GATE_DRIVE_BH (yellow) and Figure 101 PWM signal GATE_DRIVE_BH (yellow) and
GATE_DRIVE_BL (pink) with 4 pu dead-time, GATE_DRIVE_BL (pink) with 1 pu dead-time,
blue channel is Phase B motor voltage blue channel is Phase B motor voltage
Figure 102 shows the effect of varying one of the “tuning” components around the motor drive stage. In this case, the
capacitor which couples high-frequency ringing through the RCD clamp circuit (C73 in Figure 22) has been changed from
the default value of 1 nF to a new value of 10 nF. Compare the amplitude of overshoot on the channel 3 waveform
(A_PHASE) to the previous plot in Figure 101.
Figure 102 PWM gate drive phase A HI (yellow) and low (pink) with 1 pu deadband,
blue channel is Phase A motor voltage, C73 = 10 nF
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 65
For the testing below, the nominal conditions of 48V supply, and motor with no dynamometer brake load were used.
Figure 104 and Figure 105 show the results of repeated runs of motor identification, and illustrate the repeatable nature
of the identification process.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 66
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 67
any contributions to latency or signal distortion by the CAN transceiver, protection circuits, or digital isolator are
included in the results.
For the CAN receiver tests, a separate SN65HVD255D evaluation module (SN65HVD255DEVM) was used to generate the
differential bus signals (CAN_H and CAN_L) from a signal generator output. The differential signals were connected to
J3-1 (CAN_EXT_L) and J3-2 (CAN_EXT_H) as inputs to the CAN receiver circuit. The isolated received signal was
monitored on J4-3 (uc_CAN_RX). As with the transmitter tests, any contributions to latency or signal distortion by the
CAN receiver, protection circuits, or digital isolator are included in the results.
Figure 106 CAN transmitter signals showing negligible propagation delay and minimal duty cycle distortion
Figure 107 illustrates the stability of the 5V supply (derived from the auxiliary winding on the flyback converter) during
the transitions between CAN transmitter dominant and recessive states. When the transmitter is in recessive mode,
there is only a small bias current drawn from the 5V_CAN_A supply. When in dominant mode, the transmitter creates a
differential output voltage of about 2.8V across the 120 Ohm termination load (R15 and R17), increasing the current by
about 23 mA. As shown, there is no significant variation of the 5V supply, which is represented on channel 3 (purple).
For completeness, Figure 108 shows the stability of the 12V_A supply during similar CAN transmitter transitions.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 68
Figure 107 5V supply voltage response when transmitting Figure 108 12V_A flyback response when transmitting
Figure 109 CAN receiver test showing propagation delay and duty cycle distortion
Note also that the incoming duty cycle is within 1% of a square wave (50% duty cycle) on both CAN_EXT_H and
CAN_EXT_L. The outgoing received signal uC_CAN_RX has slightly more duty cycle distortion, but the contribution from
the receiver and isolator is less than 2%.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 69
Figure 110 Thermal image - no dynamometer Figure 111 Thermal image - 0.5 Nm load, 1000
brake, 100 RPM RPM (75W/52W)
In Figure 111, the dynamometer brake load is
Figure 110 shows the temperature profile of the 0.5 N-m, with the motor running at 1000 RPM.
board with the LaunchPad processor running, The electrical power from the 48V supply is 75
and the unloaded motor running at 100 RPM. Watts, and the mechanical power delivered to
Note that the hottest part of the image is the the dynamometer is 52 Watts. The motor drive
C2000 Piccolo real-time microcontroller; the FETs have increased in temperature, while the
motor drive stages are not dissipating any microcontroller is about the same temperature,
significant amount of power. and is still the hottest component in the image.
The maximum temperature in the image has
increased slightly to 47.2 degrees Centigrade.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 70
Figure 112 Thermal image - 1 Nm brake, 1000 Figure 113 Thermal image - 1 Nm load, 1500 RPM,
RPM, (170W/105W) (233W/158W)
In Figure 112 the dynamometer brake load has In Figure 113 the dynamometer brake load is
been increased to 1 N-m, and the motor speed still 1 N-m, and the motor speed has been
is still 1000 RPM. This gives a mechanical power increased to 1500 RPM. This gives a mechanical
delivered of 105W, and the electrical power power delivered of 158W, and the electrical
from the 48V supply is 170W. Under these power from the 48V supply is 233W. Q10 is
conditions, Q10, one of the FETs which supplies again the hottest component in the image, with
the 48V power to the drive stage, is the warmest a surface temperature of about 66 degrees
component in the image. Centigrade.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 71
8 Design Files
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TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 73
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 74
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The bill of materials below is for reference; to download the latest complete bill of materials for this
design, see the design files at http://www.ti.com/tool/tida-00281
Table 2: TIDA-00281 BOM
Item # Designator Quantity Value Part Number Manufacturer Description
1 !PCB1 1 TIDA-00281 Any Printed Circuit
Board
2 3V3_B, 3V3_CAN, 15 Red 5000 Keystone Test Point,
12V_B, 12V_FLY_B, Miniature, Red, TH
48V_BATT_B,
48V_MOTOR_B,
A_CURRENT,
ADC_1V65,
B_CURRENT,
C_CURRENT,
EN_3V3, LP_3V3,
PHASE_A,
PHASE_B, PHASE_C
3 5V_A, 5V_CAN, 8 Orange 5003 Keystone Test Point,
5V_I_N, 5V_I_P, Miniature,
12V_A, Orange, TH
12V_BATT_A,
DIS_FLYBACK,
PSR_FB
4 C1, C10 2 680pF C0603C681K5RACTU Kemet CAP, CERM, 680
pF, 50 V, +/- 10%,
X7R, 0603
5 C2, C9, C15, C22, 10 0.1uF C2012X7R2A104K TDK CAP, CERM, 0.1
C26, C54, C63, C76, µF, 100 V, +/- 10%,
C90, C99 X7R, 0805
6 C3, C4, C7, C8, C14, 18 10uF GRM32ER71H106KA12L MuRata CAP, CERM, 10uF,
C18, C23, C24, C29, 50V, +/-10%, X7R,
C30, C34, C39, C51, 1210
C52, C53, C79, C93,
C102
7 C5, C16, C17 3 220uF EEV-FK2A221M Panasonic CAP, AL, 220 µF,
100 V, +/- 20%,
0.153 ohm, SMD
8 C11, C12, C32, C36, 27 0.1uF C1608X7R1E104K TDK CAP, CERM, 0.1
C37, C40, C44, C45, µF, 25 V, +/- 10%,
C46, C55, C59, C75, X7R, 0603
C78, C80, C81, C82,
C83, C84, C85, C89,
C92, C94, C98,
C101, C103, C104,
C105
9 C13 1 0.22uF 0805YC224KAT2A AVX CAP, CERM, 0.22
µF, 16 V, +/- 10%,
X7R, 0805
10 C20, C21, C31, C49, 11 2200pF GRM155R71E222KA01D MuRata CAP, CERM, 2200
C68, C69, C70, C71, pF, 25 V, +/- 10%,
C106, C107, C108 X7R, 0402
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Route voltage feedback traces away from other noisy traces or components, like clock lines. Avoid
routing things under the switch node of a power inductor altogether if possible.
• Feedback nodes are generally high impedance lines which are quite sensitive to disturbances. The switch
node can radiate a significant amount of energy and could couple noise into FB traces or other sensitive
lines. Placing these traces on the other side of the board (with ground planes between them) helps
mitigate ill effects as well.
It is critical that analog/control loop components be placed such that their trace lengths back to the IC
are minimized. Below is an example of the feedback and compensation components for the TPS62152
DC-DC converter:
The feedback and compensation nodes are especially high impedance and thus susceptible to picking
up. As these are critical in the operation of the devices control loop, poor placement and routing of
these components/traces can affect the performance of the device by introducing unwanted parasitic
inductances and capacitances.
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Figure 126: Layer stack up, GND plane separating top layer power circuits from bottom layer signals
Wherever practical, keep power traces/pours on the same layer. This isn’t always possible due to
routing requirements. This will minimize the inductance of the path (by using as few vias as possible) by
keeping individual power traces on the same layer, and reduce any noise coupling between planes by
reducing overlap. Unfortunately, due to the number of different rails in this design, and the routing
requirements needed to get them to the EVM connectors, this wasn’t totally possible on this board.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 85
Use wide copper areas/traces for routing outputs of the converters to the connectors or loads. This
reduces the I*R drop along the power path and thus improves load regulation:
1
• The resistivity of a trace drops as the width of the trace increases �𝑅 ∝ �. If not using DCDC/linear
𝑊
converters capable of differential remote sensing, care must be taken that the voltage drop from the
location of regulation (close to the converter) to the load is not significant. While there isn’t really a
maximum limit on this, there is a minimum. PCB traces, like wires, are rated for current ranges based on
their cross-sectional area. This depends not only on the width but also on the thickness/height of the
trace. Calculators are available online for calculating minimum trace width.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 86
Minimize the loop area and series path inductance of the switching return current in a DCDC converter.
It is preferable that this be on the same layer and can be achieved by careful placement of the
components.
• Since it is not always convenient to guarantee a good return path on the same layer, we can drop
ground vias to an internal plane which is not broken up providing a more direct return path. The figure
below shows the use of these ground vias where it was not possible to create a small loop on the top
layer.
The power inductors should be close to the switch node pins of the ICs, minimizing the distance from
the pin to the inductor, but maintaining large area as much as possible. The goal is to minimize both the
parasitic inductance, as well as reduce the radiated emissions from the node:
If a bootstrap capacitor is used, place this component as close to the power inductor as practical.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 87
This is illustrated in Figure 131 and Figure 132 where the physical separation of the A (12V battery) ground
and B (48V battery) ground is easily observed.
Figure 131 GND_A traces highlighted Figure 132 GND_B traces highlighted
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 88
On the left is the polygon for 48V_BATT_B, from the input connector to the large filter inductor L2, as well as the
filtering capacitors. Note that while the red (top) layer is visible, this polygon shape is also found on the bottom
(blue) layer, with vias to connect the two layers.
The middle image shows the 48V_FILTERED_B polygon, which connects the output of the filter inductor (L2) to
the 48V switching circuit. Again the polygon is copied on the bottom layer, with numerous vias to connect the
top and bottom layers. The right image shows the polygon for 48V_MOTOR_B, which goes from the 48V
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 89
switching circuit to the three high-side driver FETs of the motor drive circuit. In this view, the bottom (blue)
layer is highlighted, with some edges of the similar top (red) layer visible.
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TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 91
Figure 136 Layout symmetry used to reduce differential-mode noise on analog signal
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TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 93
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 94
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 95
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9 Software Files
10 References
1. UCC27201A-Q1 datasheet http://www.ti.com/product/ucc27201A-q1
2. TPS40210-Q1 datasheet http://www.ti.com/product/tps40210-q1
3. TPS62152-Q1 datasheet http://www.ti.com/product/tps62152-q1
4. LM5060-Q1 datasheet http://www.ti.com/product/lm5060-q1
5. LM76410-Q1 datasheet http://www.ti.com/product/lm76410-q1
6. HVDA553-Q1 datasheet http://www.ti.com/product/hvda553-q1
7. OPA365-Q1 datasheet http://www.ti.com/product/opa365-q1
8. OPA2365-Q1 datasheet http://www.ti.com/product/opa2365-q1
9. LMT86-Q1 datasheet http://www.ti.com/product/lmt86-q1
10. ISO7331 datasheet http://www.ti.com/product/iso7331
11. TMS320F28026F, TMS320F28027F InstaSPIN-FOC Software Technical Reference Manual
http://www.ti.com/lit/ug/spruhp4/spruhp4.pdf
12. ISO 11898-2:2003 Road vehicles – Controller area network (CAN) – Part 2: High-speed medium access
unit
13. ISO 7637-2:2004 Road vehicles – Electrical disturbances from conduction and coupling – Part 2: Electrical
transient conduction along supply lines only, section 5.6
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 97
11 Terminology
ADC analog-to-digital converter
BOM bill of materials
Buck step-down switching-mode voltage converter
CAN Controller Area Network
CCS Code Composer Studio
EMC electromagnetic compatibility
EMF electromotive force
FET field effect transistor
FOC field oriented control
GND ground
MOSFET metal oxide semiconductor field effect transistor
OEM original equipment manufacturer
PCB printed circuit board
RC resistor capacitor
RCD resistor capacitor diode
SPICE Simulation Program with Integrated Circuit Emphasis
TIDA Texas Instruments Design
Trenton Reed is an Applications Engineer at Texas Instruments. As a member of the Automotive Systems
Engineering team, Trent focuses on powertrain end-equipments, creating reference designs for top automotive
OEM and Tier 1 manufacturers. He brings to this role experience in power electronics and motor drive systems
design. Trenton earned his Bachelor of Science in Electrical Engineering from the University of Central Florida in
Orlando, Fl.
Clark Kinnaird is a Systems Applications Engineer at Texas Instruments. As a member of the Automotive Systems
Engineering team, Clark works on various types of motor drive end-equipment, creating reference designs for
automotive manufacturers. Clark earned his Bachelor of Science and Master of Science in Engineering from the
University of Florida, and his Ph.D. in Electrical Engineering from Southern Methodist University.
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 98
13 Appendix
Figure 145 TINA simulation schematic for TPS62152 buck converter circuit
Figure 146 TINA simulation schematic for motor current feedback circuit
Figure 147 TINA simulation schematic for motor voltage feedback circuit
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 99
Motor Specifications
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 100
TIDUAY9 – November 2015 Automotive 1-kW 48-V BLDC Motor Drive Reference Design 101
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