Frequency doubling single-resistor current sampling method and device

A current sampling and single-resistor technology, applied in the field of single-resistor current sampling, can solve the problem of low sampling accuracy of current signals, and achieve the effect of improving the accuracy of current sampling

Pending Publication Date: 2021-11-19
SHANGHAI STEP ELECTRIC
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Problems solved by technology

In order to ensure that the three-phase current can be obtained accurately, the single-resistor current sampling method has certain requirements on the sampling window and sampling time. In order to meet these requirements, in the prior art, only one set of current signals is generally collected in one carrier cycle, that is, current sampling The frequency is the same as the carrier frequency, which also leads to low sampling accuracy of the current signal

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  • Frequency doubling single-resistor current sampling method and device
  • Frequency doubling single-resistor current sampling method and device
  • Frequency doubling single-resistor current sampling method and device

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Embodiment Construction

[0016] Please refer to figure 1 . According to the frequency-multiplied single-resistor current sampling method of the embodiment of the present invention, sampling the bus current through the sampling resistor set on the bus of the three-phase inverter circuit includes the following steps:

[0017] a. Adjust the three-phase duty cycle D[a], D[b], and D[c] calculated by the PWM control algorithm, and obtain the adjusted three-phase duty cycle as D 1 [a], D 1 [b], D 1 [c], and D 2 [a], D 2 [b], D 2 [c]; where D 1 [a], D 1 [b], D 1 [c] is the three-phase duty cycle of one of the first half cycle or the second half cycle of the carrier cycle, D 2 [a], D 2 [b], D 2 [c] is the other three-phase duty cycle of the first half cycle or the second half cycle of the carrier cycle;

[0018] b. Calculate the current sampling time t according to the adjusted three-phase duty ratio s1 , t s2 , t s3 and t s4 ;

[0019] c. Output the three-phase voltage according to the adjust...

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Abstract

The invention discloses a frequency doubling single-resistor current sampling method and device. The method comprises the following steps of a, adjusting a three-phase duty ratio calculated by a PWM control algorithm, and obtaining the adjusted three-phase duty ratio, b, calculating current sampling moments ts1, ts2, ts3 and ts4 according to the adjusted three-phase duty ratio, c, outputting a three-phase voltage according to the adjusted three-phase duty ratio, and d, conducting current sampling at the current sampling moments ts1, ts2, ts3 and ts4, reconstructing three-phase currents of the first half period and the second half period of the carrier period according to current sampling results, and then acquiring the three-phase average current of the carrier period. The current sampling precision of the single-resistor current sampling method can be improved.

Description

technical field [0001] The invention relates to single-resistance current sampling technology. Background technique [0002] The frequency converter is generally a three-phase output and is used to control a three-phase AC motor. Inverters generally require three-phase current signals to realize motor control, and at the same time, protection of the inverter and the motor must also be realized based on the three-phase current signals. There are many ways to obtain the three-phase current signal. Obtaining the current signal through the sampling resistor is a common current sampling method. According to the number of sampling resistors, current sampling methods can be divided into three-resistor current sampling, two-resistor current sampling and single-resistor current sampling, among which the hardware cost of single-resistance current sampling is the lowest. When the system cost is high, single-resistor current sampling is a better choice. [0003] The single-resistor c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R19/25
CPCG01R19/25
Inventor 李柏松陈伟成爱军时迎亮李武君
Owner SHANGHAI STEP ELECTRIC
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