Frequency converter overvoltage protection
US7294989B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 9, 2005 |
| Grant date | Nov 13, 2007 |
| Priority date | — |
| Expiry date | Jan 18, 2026 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M1/32
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method of protecting a frequency converter against overvoltage by controlling an AC motor during braking or during light load and a frequency converter, wherein the frequency converter is a voltage-controlled PWM frequency converter operating in single quadrant (1Q) and comprising at least one uncontrolled rectifier bridge (10) to be connected to a AC supply line (UL1, UL2, UL3), a direct-voltage intermediate circuit and at least one controlled inverter bridge (11) for feeding an AC motor (12) with an alternating voltage (Uu, Uv, Uw) of varying magnitude and frequency, in which method: the angle (θΔ) between the output voltage vector (Us) and current vector (Is), i.e. the power factor, is measured, the angle (θΔ) between the output voltage vector (Us) and current vector (Is), i.e. the power factor, is controlled on the basis of the measurement, and the angle (θΔ) between the output voltage vector (Us) and current vector (Is), i.e. the power factor, is controlled so that the angle does not exceed a preset threshold value, preferably approximately π/2.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.