Vacon Oy

Pekka Hemminki

Jani Matti Perkiö

Ari Ristimäki

Juha Norrena

Tommi Keski-Kujala

Tuomas Yli-Rahnasto

Antti Sorri

The invention is directed at an electric power converter, such as an electric motor drive for driving an electric motor. The converter includes a cooling system with a heat sink for dissipating thermal energy generated by the converter and with coolant flow means for cooling the heat sink, first measuring means for measuring the coolant inlet temperature, second measuring means for measuring the heat sink temperature, estimating means for estimating the thermal energy transferred to the heat sink, wherein the converter is provided for estimating the thermal resistance of the heat sink based on the measured temperatures and the estimated thermal energy transferred to the heat sink, for comparing the estimated thermal resistance to reference values and for outputting a signal, if the difference between the estimated thermal resistance and the reference values exceeds a threshold value. The invention is also directed at a method for operating the electric power converter.

Electric power converter, such as an electric motor drive for driving an electric motor and method for operating the electric motor drive

An electronic circuit includes: a first series-connection of DC link capacitors (C, . . . , C) and a second series-connection of DC link capacitors (C, . . . , C) connected in parallel between DC bus bars (DC+, DC&#x2212;), wherein the first series has a first node (A) between the DC link capacitors thereof and the second series has a second node (B) between the DC link capacitors thereof; and a short-circuit module () configured to receive a voltage difference (UM) between the first node and the second node and to cause the DC bus bars short circuited in response to the received voltage difference being greater than a predetermined threshold.

Safety design for DC link capacitors

A safety circuit coupled between a first direct current (DC) circuit and a second DC circuit, wherein the first DC circuit supplies power to the second DC circuit. The safety circuit comprises a first series connection between positive poles of the first and second DC circuits (the first series connection comprising a first diode, a second diode and a first controllable switch), a second series connection between negative poles of the first and second DC circuits (the second series connection comprising a third diode, a fourth diode and a second controllable switch), a first energy storage device (coupled between the positive pole of the second DC circuit and the first terminal of the second controllable switch), and a second energy storage device (coupled between the negative pole of the second DC circuit and the first terminal of the first controllable switch). The safety circuit further comprises a first feedback circuit for indicating an active state of the first controllable switch and a second feedback circuit for indicating an active state of the second controllable switch.

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Laihia, Finland

Pekka Hemminki