A Phase Shift Compensation Method for Single Resistor Current Sampling

Abstract

The invention discloses a phase shift compensation method for single resistance current sampling. The method comprises the steps of (S20) judging whether T1+T2 is larger than 2*Tmin or not, executing a step S(31) if so, and executing a step (S32) if not; (S31) judging whether T1 is larger than or equal to Tmin, executing a step (S41) if so, and carrying out phase shift compensation on a middle phase and then executing a step (S41) if not, (S32) judging whether T1 is larger than or equal to Tmin, and executing a step (S42) if so, and carrying out phase shift compensation on a maximum phase and then executing a step (S42) if not; (S41) judging whether T2 is larger than or equal to Tmin, executing a step (S51) if so, and carrying out phase shift compensation on a middle phase and then executing a step (S51) if not; (S42) judging whether T2 is larger than or equal to Tmin, executing a step (S52) if so, and carrying out phase shift compensation on a minimum phase and then executing a step (S52) if not, (S51) sampling at two sides of the maximum phase and the minimum phase, and (S52) sampling at the same sides of the maximum phase and the middle phase. According to the phase shift compensation method, T1 or T2 is always larger than the minimum current sampling time Tmin, and thus a sampling blind area is completely eliminated.

Description

technical field [0001] The invention relates to the field of single-resistance current sampling, in particular to a phase-shift compensation method for single-resistance current sampling. Background technique [0002] The working principle of the single-resistor current sampling technology is to use the sampling resistor installed on the DC bus to realize the three-phase current sampling of the motor through an appropriate algorithm. Compared with the traditional two-resistor sampling technology, this technology saves one sampling channel, which can further reduce the cost and size of the motor controller. However, the single-resistor current sampling technology has a situation where the controller MCU is less than the minimum current sampling time Tmin, so it is necessary to perform phase shift compensation on the duty cycle. [0003] In order to ensure that the controller MCU satisfies the condition of being greater than the minimum sampling time Tmin, there have been man...

AI Technical Summary

Problems solved by technology

This overcomes the problem of inaccurate control due to duty cycle changes when the sampling time of the traditional scheme is short

However, under the extreme working condition of the motor running at high speed, the existing technology has a sampling blind zone that cannot meet the condition of being greater than the minimum current sampling time Tmin no matter how the phase is shifted, resulting in inaccurate current sampling

[0004] Another example is the Chinese invention patent with the publication number CN105450094A disclosing a current sampling method and air-conditioning equipment. By judging whether the sampling current is an effective current, if it is determined that the sampling current corresponding to the nth sampling is invalid, the n-1th sampling The current estimated value of the sampling current is used as the sampling current of the nth sampling; for another example, the Chinese invention patent whose publication number is CN106208826A also discloses an overmodulation control method for a permanent magnet synchronous motor without a three-phase current sensor. When sampling with a single resistor, the reference voltage is modified, and all three phases are moved; the algorithm is not only complicated, but also under the extreme working condition of the motor running at high speed, there is a sampling blind zone that cannot meet the condition of being greater than the minimum current sampling time Tmin no matter how the phase is shifted. lead to inaccurate current sampling

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