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Brushless Electric Wrench Application Solution
Brushless Electric Wrench Application Solution
2024.05.10

Overview of the Scheme

Brushless electric wrenches are widely used in automobile maintenance, machinery manufacturing, construction engineering and other fields. They can greatly improve work efficiency and reduce the labor intensity of operators, while ensuring the safe tightening of bolts and nuts.

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Brushless DC motor is the core component in brushless electric wrench. Brushless DC motor adopts advanced electronic control technology, which controls current and voltage through electronic regulator to realize stepless speed regulation and stable output of the motor. The motor rotor of the brushless electric wrench consists of multiple pairs of permanent magnets with no direct physical contact with the fixing sub, resulting in less friction loss, lower power consumption and longer life. The electric wrench solution based on PY32F003 of Puya Semiconductor can better control the motor to run stably and efficiently.

Brushless electric wrenches are usually powered by lithium batteries for portability and flexibility. They usually have adjustable torque output and can be used in different working environments, such as construction sites, workshops, repair stores and so on. The PY32F003 chip-based control of the electric wrench not only displays the power level of the lithium battery, but also has protection against faults such as over-current and over-voltage and under-voltage, which can effectively improve the life of the lithium battery and increase the user experience.

So the electric wrench controlled by PY32F003 has the advantages of low cost, high security, good stability, etc. We also provide customers with complete motor control solutions.

Features of electric wrench based on PY32F003:

Ø Using MCU's internal 24MHz main frequency, the speed loop response is faster.

Ø The DMA method acquires the ADC reverse potential, effectively avoiding out-of-step.

Ø Built-in comparator provides overcurrent protection and high integration to protect battery life.

Ø Puya sensorless motor starting algorithm with 100% starting success rate.

Ø Over-voltage, under-voltage, software over-current, blocking, phase loss protection.

Ø Power display, fault indication, high and low gear switching, reverse zero torque self-stopping, forward and reverse switching, work lighting.


2  Application Block Diagram

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3  PY32F003 Series MCUs

The main control MCU is based on PY32F003 series microcontroller, which has balanced processing performance, absolute stability performance, rich peripheral interface and reliable safety performance. It provides mainstream solutions for various motor application scenarios and meets the requirements of high reliability and stability of motors.

PY32F003 series MCUs can be widely used in a variety of motor scenarios, such as motor control systems for electric wrench, fascia guns, high-speed blowers, violent fans, water pumps, pumps, electric toothbrushes, massagers, and so on.

Ø 32-bit ARM® Cortex® - M0+

Ø Maximum 64 Kbytes flash memory

Ø Maximum 8 Kbytes SRAM

Ø Up to 32 MHz operating frequency

Ø Communication Interface: SPI *1, USART *2, I2C *1

Ø Provides a 12-bit ADC, 2 comparators, an advanced timer (TIM1), 4 general-purpose timers (TIM3/TIM14/TIM16/TIM17)

Ø Operating Voltage: 1.7 V ~ 5.5 V

Ø Operating temperature range: -40 ~ 85°C


4  Technical Parameters

No.

Functionality

Parameters

Note

1

Forward and reverse functions

Motor forward and reverse

The main switch provides a commutation signal, and the control board controls the motor forward and reverse.

2

Brake function

Braking time < 1s

1. E-brake
2. Brake within 1s after switch is fully released

3

Speed control function

Speed range: 0~100%
 Full speed19000RPM±10%

The main switch provides VR speed control signal and the control board performs PWM speed control.

4

Task lighting

Illuminated lamp is always on during normal operation

Illumination

5

Time-delayed lighting

Normal operation after the switch is completely released, the LED will remain on and go out after a 10s delay.

6

Battery level display

1. Low battery light flashing: voltage <16.8V (flashing frequency 300ms uninterrupted)
2. Low battery light is always on: 16.8V
3. Medium battery light is always on: 17.8V
4. High battery light is always on: voltage>18.8V

7

Battery overdischarge protection

≤ 15±0.3V

When the battery voltage is lower than 15V±0.3V, the machine stops after a delay of 500±100ms.

8

MOS tube over-temperature protection

105±3°C

When the temperature of the MOS tube is higher than 100±3, the machine will be shut down after a delay of 500±100ms.

9

Overcurrent protection

40A

Downtime protection

10

Current limit

35A

11

Short circuit protection

≥60A/30±10ms

Shutdown protection when load current is greater than 60A

12

Phase-to-phase short circuit

With motor phase line short circuit protection function

 

 PCBA

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