Texas Instruments MCT8316A Tuning Manual Download Page 20 | Manualshive

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Texas Instruments MCT8316A Tuning Manual Download Page 20

when fast deleration is disabled is around 10 seconds.

shows phase current and motor electrical

speed waveform when the motor decelerates from 100% duty cycle to 10% duty cycle. Time taken for the motor
to decelerate from 100% duty cycle to 10% duty cycle when fast deleration is enabled is around 1.5 seconds.
Please note that when fast deceleration is enabled and anti-voltage surge (AVS) is disabled, there might be
voltage spikes seen in supply voltage. Enable AVS to protect the power supply from voltage overshoots during
motor deceleration.

Phase current

Speed

Figure 4-3. Phase current and motor speed - Faster deceleration disabled

Phase current

Speed

Figure 4-4. Phase current and motor speed -Faster deceleration enabled

4.3.8 Preventing supply voltage overshoot during motor stop and deceleration

For applications that require preventing supply voltage overshoots during motor stop or deceleration, it is
recommended to follow below steps.

Preventing supply voltage overshoot during motor stop:

Basic Controls

20

MCT8316A Tuning Guide

SLLU336 – MAY 2021

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Copyright © 2021 Texas Instruments Incorporated

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Summary of Contents for MCT8316A

Page 1: ...igure 2 3 MCx8316A EVM External Configuration 4 Figure 3 1 Fault Status 10 Figure 4 1 Reverse Drive Function 14 Figure 4 2 Phase current FG and motor speed Faster startup time 18 Figure 4 3 Phase current and motor speed Faster deceleration disabled 20 Figure 4 4 Phase current and motor speed Faster deceleration enabled 20 List of Tables Table 3 1 Ultra Slow Acceleration Default Values 5 Table 3 2 ...

Page 2: ... sections Essential controls and Basic controls This process is also detailed in the Guided tuning section in the GUI Essential controls Tuning steps to successfully spin the motor in closed loop Basic controls Tuning steps to conform to use case and explore features in the device 2 1 Hardware and GUI setup Below are the items that are required to run through this tuning guide 1 MCx8316AEVM Board ...

Page 3: ...er configuration as shown in Figure 2 2 Red boxes indicate where jumpers should be installed on the EVM Figure 2 2 MCx8316A EVM Jumper Configuration www ti com Introduction SLLU336 MAY 2021 Submit Document Feedback MCT8316A Tuning Guide 3 Copyright 2021 Texas Instruments Incorporated ...

Page 4: ...d automatically connect to the EVM as shown on the status bar located on the bottom of this GUI If the GUI doesn t connect automatically please ensure that the FTDI serial port is selected by going to the top menu Options Serial Port Then click on the chain link icon on the left of the status bar to connect to the EVM 2 1 3 3 Verify Hardware Connection After the GUI establishes connection with the...

Page 5: ...G_TWO_PH_PROFILE 0x00000096 0x591A44A6 150_DEG_THREE_PH_PROFILE 0x00000098 0x392ED000 PIN_CONFIG1 0x000000A4 0x00000000 PIN_CONFIG2 0x000000A6 0x00000000 DEVICE_CONFIG 0x000000A8 0x00000000 PERIPH_CONFIG 0x000000AA 0x00000000 GD_CONFIG1 0x000000AC 0x1C400000 GD_CONFIG2 0x000000AE 0x00000000 If your application requires slow acceleration such is blowers load the default values listed in Table 3 2 T...

Page 6: ...ILE 0x00000098 0x392ED000 PIN_CONFIG1 0x000000A4 0x00000000 PIN_CONFIG2 0x000000A6 0x00000000 DEVICE_CONFIG 0x000000A8 0x00000000 PERIPH_CONFIG 0x000000AA 0x00000000 GD_CONFIG1 0x000000AC 0x1C400000 GD_CONFIG2 0x000000AE 0x00000000 If your application requires faster acceleration such is vacuum robots load the default values listed in Table 3 4 Table 3 4 Faster Acceleration Default Values Address ...

Page 7: ...E 0x00000096 0x591A44A6 150_DEG_THREE_PH_PROFILE 0x00000098 0x392ED000 PIN_CONFIG1 0x000000A4 0x00000000 PIN_CONFIG2 0x000000A6 0x00000000 DEVICE_CONFIG 0x000000A8 0x00000000 PERIPH_CONFIG 0x000000AA 0x00000000 GD_CONFIG1 0x000000AC 0x1C400000 GD_CONFIG2 0x000000AE 0x00000000 If you are not sure of your application load the default values listed in Table 3 6 Table 3 6 Default Values Address Name A...

Page 8: ...anded to the device To command the speed via I2C go to the Quick Tuning page within the GUI and toggle the Enable Speed Control via I2C in the I2C Control Section 3 2 2 Speed input PWM frequency range selection If the Speed input mode in section 2 2 1 is selected as PWM Mode speed input select the range of PWM input frequency 3 3 Algorithm configuration Motor parameters 3 3 1 Maximum motor electri...

Page 9: ...eaches maximum speed 3 5 Testing for successful startup into closed loop 1 Apply a nonzero speed command a If the Speed input mode is I2C change the I2C Speed Command Percentage to a non zero value Once the speed command is issued the device will start commutating and the motor should start spinning that is proportional to the I2C Speed Command Percentage b If the speed input mode is Analog rotate...

Page 10: ...quencies above the configured abnormal speed threshold LOCK_ABN_SPEED When this fault gets triggered follow below recommendations 1 Increase align time ALIGN_TIME 2 Decrease slow first cycle frequency SLOW_FIRST_CYC_FREQ 3 Decrease open loop acceleration A1 OL_ACC_A1 and open loop acceleration A2 OL_ACC_A2 4 Decrease closed loop acceleration CL_ACC 3 6 2 Loss of Sync LOSS_OF_SYNC This fault gets t...

Page 11: ..._FREQ_OUT Step 4 Increase Min duty cycle MIN_DUTY during closed loop operation Please note that device might trigger Loss of sync LOSS_OF_SYNC when motor phases are disconnected while the motor is spinning 3 6 4 Cycle by cycle current limit CBC_ILIMIT Cycle by cycle current limit CBC_ILIMIT gets triggered when the motor startup time is too low and the open loop acceleration is too high If this fau...

Page 12: ...mportant to save power while the device is not spinning the motor In sleep mode all motor outputs are disabled the charge pump is disabled the AVDD regulator is disabled and the serial communication bus is disabled MCT8316A can be configured to be in sleep mode by configuring register bits DEV_MODE Please note that in Sleep mode GUI will lose connectivity as there will be no I2C communication 4 1 ...

Page 13: ...CT8316A is driving the motor When FG_CONFIG is configured to 1 FG active till BEMF drops below FG_BEMF_THR MCT8316A provides FG output until BEMF falls below FG_BEMF_THR The FG output will continue to indicate motor speed even if the motor is not being actively driven This mode is useful in applications that require motor speed information above a certain speed and rotor motion information during ...

Page 14: ...direction opposite to the intended direction of spin if motor phase wires are connected to OUTA OUTB and OUTC in wrong sequence or when wrong direction command is issued Motors with higher inertia coast for a longer period of time It is recommended to have ISD enabled in applications that require frequent motor starts and stops and use higher inertia motors Step 1 Enable ISD ISD_EN Step 2 Enable M...

Page 15: ...reasing the threshold till the motor starts up successfully Note that the IPD current threshold should not be higher than the rated current of the motor Use Equation 3 to choose the correct IPD_CURR_THR IPD_CURR_THR V IPD current tℎresℎold A CSA_GAIN V A 3 Step 3 Select IPD clock value IPD_CLK_FREQ The IPD clock defines how fast the IPD pulses are applied Higher inductance motors and higher curren...

Page 16: ...ions where the startup torque is high the motor might lose synchronization In such applications it is recommended to decrease the frequency In applications where jerky motions are observed it is recommended to increase the frequency 4 3 4 Faster startup timing Startup time is the time taken for the motor to reach closed loop from zero speed For applications that require quick startup time we recom...

Page 17: ...oop acceleration constants OL_ACC_A1 and OL_ACC_A2 and also retune IPD by increasing the IPD current threshold IPD_CURR_THR and IPD repeat times IPD_REPEAT Step 9 Increase Closed loop acceleration rate CL_ACC Closed loop acceleration rate CL_ACC can be increased until closed loop current reaches Lock detection current threshold LOCK_ILIMIT Closed loop current can be measured using oscilloscope Inc...

Page 18: ... it is recommended to tune Speed loop PI controllers SPD_LOOP_KP and SPD_LOOP_KI Kp coefficient of speed loop SPD_LOOP_KP controls the settling time and speed overshoots Ki coefficient of Speed loop SPD_LOOP_KI controls speed overshoot and ensures regulation of speed at set value and drives the error to zero Step 1 Enable speed loop SPEED_LOOP_DIS Step 2 Tuning speed loop Kp SPD_LOOP_KP and Ki SPD...

Page 19: ...st deceleration FAST_DECEL_EN Note Fast deceleration will be active till the input speed duty cycle decelerates to brake duty threshold BRAKE_DUTY_THRESHOLD Device will engage High side or low side braking when the input speed duty cycle is below the brake duty threshold BRAKE_DUTY_THRESHOLD 4 3 7 Faster deceleration Follow below steps to decelerate the motor quickly Step 1 Configure closed loop d...

Page 20: ...S to protect the power supply from voltage overshoots during motor deceleration Phase current Speed Figure 4 3 Phase current and motor speed Faster deceleration disabled Phase current Speed Figure 4 4 Phase current and motor speed Faster deceleration enabled 4 3 8 Preventing supply voltage overshoot during motor stop and deceleration For applications that require preventing supply voltage overshoo...

Page 21: ...MCT8316A provides options to either latch LOCK_LIMIT fault or auto retry for AUTO_RETRY_TIMES after every LCK_RETRY seconds This can be configured in LOCK_ILIMIT_MODE We have defaulted the auto retry time and lock retry 4 3 10 Maximizing thermal efficiency and increasing thermal performance Thermal performance can be improved by minimizing power dissipation Power dissipation across RDS on Switchin...

Page 22: ... follow below recommendations to improve the motor efficiency Step 1 Configure PWM Mode PWM_MODE to Single ended mode In this mode switching losses are lower compared to Complementary mode Step 2 In closed loop set the motor speed to the desired operating load speed region Set the lead angle polarity LD_ANGLE_POLARITY and tune the lead Angle LD_ANGLE in both directions till minimum motor phase cur...

Page 23: ...s are subject to change without notice TI grants you permission to use these resources only for development of an application that uses the TI products described in the resource Other reproduction and display of these resources is prohibited No license is granted to any other TI intellectual property right or to any third party intellectual property right TI disclaims responsibility for and you wi...

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