Mid-voltage variable-frequency driving system and total harmonic distortion compensation control method

Patent metadata

Field	Value
Publication number	US-9231406-B2
Application number	US-201213430722-A
Country	US
Kind code	B2
Filing date	Mar 27, 2012
Priority date	Sep 23, 2011
Publication date	Jan 5, 2016
Grant date	Jan 5, 2016

Abstract

A mid-voltage variable-frequency driving system and a total harmonic distortion compensation control method are provided in this invention. The mid-voltage variable-frequency driving system includes a total harmonic distortion compensation unit. The total harmonic distortion compensation unit is used to perform an optimal adjustment on a reactive component reference value of a grid-side phase current, such that a harmonic component of the grid-side phase current may be reduced and a power factor of a three-phase switch-mode rectifier module within the mid-voltage variable-frequency driving system may be maintained.

First claim

What is claimed is:

1. A total harmonic distortion compensation control method, used in a three-phase switch-mode rectifier module, wherein the three-phase switch-mode rectifier module is coupled to a three-phase electrical grid for converting an AC voltage input on the three-phase electrical grid into a DC voltage, and the total harmonic distortion compensation control method comprises: performing harmonic detection on a grid-side phase current flowing into the three-phase switch-mode rectifier module; stopping adjusting a reactive component reference value of the grid-side phase current when a harmonic component of the grid-side phase current does not reach a predetermined harmonic value, so as to form a final reactive component reference value, or further determining a phase angle difference between a fundamental component of a rectifier AC-side phase current and a fundamental component of a rectifier AC-side phase voltage of the three-phase switch-mode rectifier module when a harmonic component of the grid-side phase current exceeds the predetermined harmonic value; stopping adjusting the reactive component reference value when the phase angle difference is a predetermined phase angle difference value, or further determining a power factor of the three-phase switch-mode rectifier module when the phase angle difference is not a predetermined phase angle difference value; and stopping adjusting the reactive component reference value when the power factor does not reach a predetermined power factor value, or adjusting the reactive component reference value when the power factor exceeds the predetermined power factor value, so as to change the final reactive component reference value; comparing a reactive component of the grid-side phase current with the final reactive component reference value; and adjusting the three-phase switch-mode rectifier module according to the comparison result above, until the reactive component of the grid-side phase current approaches the final reactive component reference value.

2. The total harmonic distortion compensation control method of claim 1 , wherein the predetermined harmonic value is a preset value or an online optimized value.

3. The total harmonic distortion compensation control method of claim 1 , wherein the predetermined phase angle difference value is zero, a preset nonzero value or an online optimized value.

4. The total harmonic distortion compensation control method of claim 1 , further comprising:
adjusting the three-phase switch-mode rectifier module with different reactive component reference values in an allowance range of a power factor, and respectively performing harmonic detection under conditions of different reactive component reference values to obtain a plurality of harmonic components and a plurality of corresponding phase angle differences; and
selecting an optimal harmonic component value and a corresponding optimal phase angle difference value from the harmonic components and the corresponding phase angle differences.

5. The total harmonic distortion compensation control method of claim 4 , wherein the optimal harmonic component value is applied as the predetermined harmonic value, so as to determine whether the harmonic component of the grid-side phase current exceeds the predetermined harmonic value, and the optimal phase angle difference value is applied as the predetermined phase angle difference value, so as to determine whether the phase angle difference between the fundamental component of the rectifier AC-side phase current and the fundamental component of the rectifier AC-side phase voltage is the predetermined phase angle difference value.

6. A total harmonic distortion compensation control method for a mid-voltage variable-frequency driving system comprising a three-phase switch-mode rectifier module, a three-phase electrical grid, a controller and a total harmonic distortion compensation unit, wherein the three-phase switch-mode rectifier module is coupled to the three-phase electrical grid, and the controller is coupled to the three-phase switch-mode rectifier module, and the total harmonic distortion compensation unit is coupled to the controller, and the total harmonic distortion compensation control method comprises: inputting an initial reactive component reference value into the total harmonic distortion compensation unit, wherein the total harmonic distortion compensation unit adjusts the initial reactive component reference value to generate a final reactive component reference value; and controlling each single-phase rectifier circuit of the three-phase switch-mode rectifier module through the controller according to the final reactive component reference value generated by the total harmonic distortion compensation unit, thus adjusting a phase angle difference of the three-phase switch-mode rectifier module, thereby adjusting a power factor corresponding to the three-phase electrical grid and eliminating a current total harmonic distortion corresponding to the three-phase electrical grid, wherein the phase angle difference exists between a fundamental component of a rectifier AC-side phase current and a fundamental component of a rectifier AC-side phase voltage of each single-phase rectifier circuit of the three-phase switch-mode rectifier module; wherein the three-phase switch-mode rectifier module comprises three sets of single-phase rectifier circuits coupled in parallel to each other, which are three-level rectifier circuits each of which receives a single-phase voltage input from the three-phase electrical grid, and the three sets of single-phase rectifier circuits are all coupled to a first output terminal, a midpoint and a second output terminal, and the three-phase switch-mode rectifier module is used for adjusting the power factor and eliminating the current total harmonic distortion.

7. The total harmonic distortion compensation control method of claim 6 , wherein an inductance is coupled between each voltage input terminal of the three sets of single-phase rectifier circuits and the three-phase electrical grid, and each of the three sets of single-phase rectifier circuits comprises at least two diodes, wherein one of the two diodes is a commutating diode for ensuring the unidirectivity of the current, and the other one of the two diodes is a non-commutating diode.

8. The total harmonic distortion compensation control method of claim 7 , wherein in the three sets of single-phase rectifier circuits, the commutating diode is operated at a switching frequency, and the commutating diode adopts a fast-recovery diode.

9. The total harmonic distortion compensation control method of claim 6 , wherein the initial reactive component reference value and the final reactive component reference value are obtained through an off-line calculation when a fundamental component of the rectifier AC-side phase current passing through the three-phase switch-mode rectifier module and a fundamental component of the rectifier AC-side phase voltage have the same direction, and the off-line calculation is performed by calculating the phase relationship between a fundamental component of a grid-side phase current flowing into the three-phase switch-mode rectifier module and a fundamental component of a grid-side phase voltage.

10. The total harmonic distortion compensation control method of claim 9 , wherein the initial reactive component reference value and the final reactive component reference value are obtained by obtaining a set of reactive component reference values through the off-line calculation and then selecting the corresponding values through a lookup table according to the operation voltage or operation load current of the three-phase electrical grid in real tim

Assignees

• Chen Wei
• Pu Bo-Yu
• Zhang Yi
• Delta Electronics Shanghai Co

Inventors

• Chen Wei
• Pu Bo-Yu
• Zhang Yi

Classifications

• H02J3/18

  Arrangements for adjusting, eliminating or compensating reactive power in networks · CPC title

• H02P27/08

  with pulse width modulation · CPC title

• Y02E40/30

  Reactive power compensation · CPC title

• H02J3/01 Primary

  Arrangements for reducing harmonics or ripples · CPC title

• Y02E40/40

  Arrangements for reducing harmonics · CPC title