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Three-phase driving bridge lower bridge arm three-resistor based motor current sampling method and system

A technology of motor current sampling and three-phase current, which is used in control systems, AC motor control, estimation/correction of motor parameters, etc., can solve the complex cost of current sampling module, short diode freewheeling time, and large sampling current error problem, to achieve the effect of easy software implementation, high current sampling accuracy, and high voltage utilization efficiency

Pending Publication Date: 2019-02-15
ZHUZHOU ELITE ELECTRO MECHANICAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Considering the impact on the three-phase drive bridge, sampling resistors with small resistance are usually used to sample the current, drive the PWM modulation signal to the three-phase bridge, then sample the sampling resistors, and finally drive the motor to run, but the motor three-phase When performing current sampling, when the driving voltage duty ratio of a certain phase of the drive is as high as 100%, the freewheeling time of the diode is short, and the switching of the power tube will cause large current fluctuations, and the sampling current error at this time is relatively large. Big
[0003] The existing technology usually adopts dual-resistor sampling on the phase and adds related circuit modules to solve the above problems, which makes the current sampling module more complicated and more expensive

Method used

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  • Three-phase driving bridge lower bridge arm three-resistor based motor current sampling method and system
  • Three-phase driving bridge lower bridge arm three-resistor based motor current sampling method and system
  • Three-phase driving bridge lower bridge arm three-resistor based motor current sampling method and system

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Embodiment 1

[0033] A method for sampling the current of a lower-end three-resistor motor to solve the problem of the existing technology image 3 The problem of inaccurate sampling of the three-phase current shown.

[0034] The PWM modulation signal in the space vector control is transmitted to the power tube of the three-phase drive bridge to drive the motor to run, and the motor current is sampled through the sampling resistor on the three-phase drive bridge. The three-phase driving voltage distribution of PWM modulation signal obtained based on space vector control is as follows: Figure 5 As shown, in each of the six sectors, the duty ratio of one of the three phases U, V, and W in each sector is as large as 100%, and the corresponding relationship between the motor rotor angle and the sector is specifically, 1°~60 °: Sector 1, 60°~120°: Sector 2, 120°~180°: Sector 3, 180°~240°: Sector 4, 240°~300°: Sector 5, 300°~360 °: Sector 6.

[0035] First, if figure 1 As shown, when the po...

Embodiment 2

[0040] A motor current sampling system based on three resistors of the lower arm of a three-phase drive bridge, comprising a three-phase drive bridge circuit unit, a sampling trigger unit, a sensor, a control unit, and a sampling resistor unit,

[0041] The input end of the three-phase driving bridge circuit unit receives the PWM driving signal, and the output end is connected to the motor; the PWM driving signal is obtained by space vector modulation, and the PWM driving signal is output by center alignment.

[0042] The sampling trigger unit receives the PWM driving signal, and is used to detect the start moment of each cycle of the PWM driving signal and generate a trigger signal to the control unit.

[0043] Exemplarily, the sampling trigger unit also includes a synchronous counter for the period of the PWM driving signal, such as Figure 4 As shown, according to the synchronous counter of the PWM modulation signal, the current sampling is triggered at the moment when the ...

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Abstract

The invention proposes a three-phase driving bridge lower bridge arm three-resistor based motor current sampling method and system. Current sampling is triggered according to periodic change of a PWMdriving signal, a section where a motor rotor is currently located is simultaneously judged, current sampling is performed by combining the characteristic of a central edge aligned to the PWM modulation signal and distribution characteristic of each phase voltage at each section, the current sampling accuracy is high, the voltage utilization efficiency is high, moreover, no complicated circuit isused, the cost is low, soft implementation is easy, and a few CPU resources are occupied.

Description

technical field [0001] The present invention relates to the technical field of motor control, and more specifically, to a motor current sampling method and system based on three resistors of the lower bridge arm of a three-phase drive bridge. Background technique [0002] In the permanent magnet brushless motor control, in order to realize the precise control of the motor, the motor current sampling is required. Currently, motor current sampling methods include such as figure 1 The motor current sampling circuit with three resistors in the lower bridge arm of the three-phase drive bridge shown in the motor samples the three-phase current of the motor U, V, and W: when the lower bridge arm of the three-phase drive bridge is fully connected, the freewheeling current of the lower bridge arm passing through the diode and the motor The three phases form a loop, and the current passing through the three sampling resistors corresponds to the real three-phase current of the motor. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02P23/14H02P27/08
CPCH02P23/14H02P27/08
Inventor 曾科童向辉高明李继铮
Owner ZHUZHOU ELITE ELECTRO MECHANICAL
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