Claims
- 1. An electric motor drive for driving an alternating-current motor comprising:
a frequency converter for controlling the electric motor, wherein the frequency converter comprises a rectifier and an inverter; an inductor unit, in a three-phase network, connecting the alternating-current power source to an input of the frequency converter to an input of the rectifier for reducing a surge current from a power source; an intermediate circuit connecting an output of the rectifier and an input of the inverter for further reducing the surge current from the power source; and a current measuring unit, in a three-phase network, measuring and/or monitoring a three-phase current to the electric motor.
- 2. The electric motor drive according to claim 1, wherein the inverter, connected from the output of the rectifier, includes switching units and produces the three-phase current and a three-phase voltage to the electric motor.
- 3. The electric motor drive according to claim 1, further comprising:
a current monitoring unit in a control unit of the inverter for supplying control pulses to a semiconductor switch in the switching units.
- 4. The electric motor drive according to claim 3, wherein the switching units in the inverter comprises:
an auxiliary switch connected to the semiconductor switch which comprises a switching transistor that includes an emitter, base and collector.
- 5. The electric motor drive according to claim 3, wherein the semiconductor switch is an insulated-gate bipolar transistor (IGBT).
- 6. The electric motor drive according to claim 4, wherein the emitter of the switching transistor receives a voltage supply via a safety relay switch, when the safety relay switch is not actuated, where the voltage allows the switching transistor to be in a conducting state,
the base of the switching transistor receives the control pulses from the semiconductor switch, and the collector, which is connected to ground, transmits undistorted control pulses to a control terminal of the semiconductor switch to supply current in the three-phase network to the electric motor.
- 7. The electric motor drive according to claim 1, wherein the intermediate circuit comprises a capacitor connected at an output terminal of the rectifier.
- 8. The electric motor drive according to claim 7, wherein the intermediate circuit comprises a switch arranged in series with the capacitor.
- 9. The electric motor drive according to claim 7, wherein the capacitor has a value of 50 μF.
- 10. A method for driving an alternating-current motor in an electric motor drive comprising:
controlling the electric motor in a frequency converter; connecting the alternating-current power source to the input of an inductor in a three-phase network unit for reducing a surge current in a power source; connecting a rectifier and inverter in the frequency converter for further reducing a surge current in the power source; and measuring and/or monitoring a three-phase current to the electric motor.
- 11. The method of claim 10, wherein the inverter, connected from an output of the rectifier, includes switching units and produces the three-phase current and a three-phase voltage to the electric motor.
- 12. The method of claim 10, further comprising:
supplying control pulses to an IGBT semiconductor switch in the switching units.
- 13. The method of claim 11, wherein the switching units in the inverter comprises:
an auxiliary switch connected to the semiconductor switch which comprises a switching transistor that includes an emitter, base and collector.
- 14. The method of claim 13, wherein the emitter of the switching transistor receives a voltage supply via a safety relay switch, when the safety relay switch is not actuated, where the voltage allows the switching transistor to be in a conducting state,
the base of the switching transistor receives the control pulses from the semiconductor switch, and the collector, which is connected to ground, transmits undistored control pulses to a control terminal of the IGBT semiconductor switch to supply current in the three-phase network to the electric motor.
Priority Claims (1)
Number |
Date |
Country |
Kind |
200112210 |
Nov 2001 |
FI |
|
Parent Case Info
[0001] This PCT application claims priority under 35 U.S.C. § 119(a) on PCT Application No(s). F120012210 filed in Finland on Nov. 14, 2001, the entire contents of which are hereby incorporated by reference.
Continuations (1)
|
Number |
Date |
Country |
Parent |
PCT/FI02/00898 |
Nov 2002 |
US |
Child |
10843292 |
May 2004 |
US |