Multi-voltage machine emulator for accurate inverter testing
Abstract
The invention describes a novel circuit topology that emulates the behavior of a rotating field machine. The precise emulation of the electrical behavior of rotating field machines allows the testing of inverters without the need for a real motor.
Advantages
- Theoretically accurate emulation of reverse voltage possible.
- No additional current fluctuation range due to the emulator.
- Higher efficiency than linear amplifiers.
- High bandwidth due to abrupt switching.
- Functional testing of drive inverters.
- Power hardware-in-the-loop test environment.
- Emulation of rotary field machines for development and tests.
Fields of application
The invention is of interest to manufacturers of machine emulators (e.g. inverter test benches in research and development; testing of inverters at inverter and electric motor manufacturers). The need for such systems may increase in the course of increasing electromobility and the use of electronically controlled electric motors in various areas.
Background
Complex machine test benches are typically used to test drive functionality. Machine emulators, which simulate the electrical behavior of the rotating field machine connected to the drive, are a more cost-effective alternative. However, previous solutions have drawbacks
Problem
Standard methods for testing machine inverters have many disadvantages, which are listed here in brief:
- Machine test benches are time intensive and expensive.
- Previous emulators cannot accurately simulate the desired counter voltage.
- Clocked power electronics introduce additional interferences.
- Increasing the switching frequency increases losses.
- Low-pass filters limit bandwidth.
- Linear amplifiers are very inefficient.
Solution
The invention from the Institute of Power Electronics and Electrical Drives (University of Stuttgart) enables an exact simulation of the electrical behavior of rotating field machines using a novel multipoint inverter with variable voltage levels. It describes a machine emulator consisting of two main components:
- Multiple single-phase inverters with low-pass filters to provide variable voltage levels.
- Bi-directional switches for fast switching between these voltage levels.
This configuration makes it possible to theoretically simulate exactly the desired reverse voltage of an induction machine without introducing additional current fluctuations. The emulator thus combines the advantages of existing solutions while avoiding their disadvantages. It is particularly suitable for accurate testing of drive inverters without the need for complex machine test benches.