Frequency converter start-up
First Claim
1. A method to start a frequency converter equipped with a direct current intermediate circuit when a permanent magnet motor whose rotor is rotating at a start-up time is connected to the frequency converter,wherein the frequency converter has a network bridge (10) and load bridge (11), and the load bridge (11) has an upper branch with controllable power semiconductor switches (V1-V3) and parallel connected zero diodes (D1-D3) a lower branch with controllable power semiconductor switches (V4-V6) and parallel connected zero diodes (D4-D6), and a direct current intermediate circuit between the network bridge (10) and load bridge (11),and the said frequency converter uses a current transducer (RDC) placed in the direct current intermediate circuit, and an analogue current signal composed by the frequency convertor features samples of measured output currents, andthe switches (V1-V3) of the upper branch of the frequency converter converter are controlled using a bootstrap method,the method comprising:
- initiating the start-up of the frequency converter by controlling the controllable power semiconductor switch of the lower branch of one output phase to a conductive state for one or several periods of time.
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Accused Products
Abstract
Method and apparatus to start a frequency converter equipped with a direct current intermediate circuit, particularly when a permanent magnet motor whose rotor is rotating at the start-up time is connected to it, wherein the frequency converter has a network bridge (10) and load bridge (11), and the load bridge has controllable power semiconductor switches of the upper and lower branch (V1-V6) and parallel connected zero diodes (D1-D6), and a direct current intermediate circuit between them, and the said frequency converter uses a current transducer placed in the direct current intermediate circuit, and the analogue current signal composed by it features samples of the measured output currents, and the diverter switches of the frequency converter'"'"'s upper branch are controlled using the bootstrap method, wherein start-up is initiated by controlling the controllable power semiconductor switch of the lower branch of at least one output phase to a conductive state for one or several periods of time, preferably of approximately 200 μs, at a time.
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Citations
20 Claims
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1. A method to start a frequency converter equipped with a direct current intermediate circuit when a permanent magnet motor whose rotor is rotating at a start-up time is connected to the frequency converter,
wherein the frequency converter has a network bridge (10) and load bridge (11), and the load bridge (11) has an upper branch with controllable power semiconductor switches (V1-V3) and parallel connected zero diodes (D1-D3) a lower branch with controllable power semiconductor switches (V4-V6) and parallel connected zero diodes (D4-D6), and a direct current intermediate circuit between the network bridge (10) and load bridge (11), and the said frequency converter uses a current transducer (RDC) placed in the direct current intermediate circuit, and an analogue current signal composed by the frequency convertor features samples of measured output currents, and the switches (V1-V3) of the upper branch of the frequency converter converter are controlled using a bootstrap method, the method comprising: initiating the start-up of the frequency converter by controlling the controllable power semiconductor switch of the lower branch of one output phase to a conductive state for one or several periods of time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus to start a frequency converter equipped with a direct current intermediate circuit when a permanent magnet motor whose rotor is rotating at a start-up time is connected to the frequency converter,
wherein the frequency converter has a control unit, network bridge (10) and load bridge (11), and the load bridge (11) has an upper branch with controllable power semiconductor switches (V1-V3) and parallel connected zero diodes (D1-D3), a lower branch with controllable power semiconductor switches (V4-V6) and parallel diodes (D4-D6), and a direct current intermediate circuit between the network bridge (10) and the load bridge (11), and the said frequency converter has a current transducer (RDC) placed in the direct current intermediate circuit, and an analogue current signal composed by the frequency converter features samples of measured output currents, and the said control unit is adapted to control the switches (V1-V3) of the upper branch of the frequency converter using a bootstrap method, wherein the control unit is adapted to initiate the start-up by controlling the controllable power semiconductor switch of the lower branch of one output phase to a conductive state for one or several periods of time.
Specification