Frequency converter, control device and control method for frequency converter
A control device and frequency converter technology, applied in the field of frequency converters, can solve problems such as DC bus overvoltage, frequency converter prone to failure, frequency converter output current overcurrent, etc.
Active Publication Date: 2020-03-06
BOSCH REXROTH (XIAN) ELECTRIC DRIVES & CONTROLS CO LTD XIAN
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Problems solved by technology
[0004] However, in the over-excitation braking of the current frequency converter, increasing the given value of the excitation current of the stator of the asynchronous motor and increasing the output voltage of the frequency converter are all realized in an open loop. Therefore, when the frequency converter performs over-excitation braking , the inverter is prone to faults, such as the output current of the inverter is overcurrent or the DC bus is overvoltage, etc.
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[0016] In the following, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0017] see now figure 1 , which shows a schematic diagram of a frequency converter according to an embodiment of the present invention. Such as figure 1 As shown, the frequency converter 100 includes a working circuit 200 and a control device 300 . Among them, the working circuit 200 is used to provide the asynchronous motor 400 with the required power supply voltage to drive the asynchronous motor 400 by changing the frequency of the power supply, which mainly includes a rectification (AC to DC) part, a filter part, an inverter (DC AC) part and drive unit etc. The control device 300 is used for performing vector control on the working circuit 200 and realizing overexcitation braking of the frequency converter 100 .
[0018] see now figure 2 , which shows a flowchart of a control method for a frequency converter according to an ...
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The invention relates to a control device and control method for a frequency converter. The control device comprises a first calculation module for generating an adjustment amount based on the difference between actual voltage of a DC bus of a frequency converter and given voltage; a second calculation module for calculating a given value of an excitation current for vector control of the frequency converter and increasing with the adjustment amount based on the features of an asynchronous motor driven by the frequency converter and the adjustment amount; and a third calculation module for generating an initial given value of a torque current based on a feedback rotational speed of the asynchronous motor and a given rotational speed, and for calculating a given value of the torque current for the vector control of the frequency converter based on the initial given value and an upper limit value and a lower limit value of the given value of the torque current, wherein absolute values of the upper limit value and the lower limit value decrease as the adjustment amount increases. The control device and control method can be used for achieving over-excitation brake of the frequency converter and preventing faults such as over-current outputted by the frequency converter and overvoltage of the DC bus and the like.
Description
technical field [0001] The invention relates to the field of frequency converters, in particular to frequency converters, control devices and control methods for frequency converters. Background technique [0002] With the development of technology, frequency conversion speed control system has been widely used in industry and daily life. The frequency conversion speed regulation system usually includes an asynchronous motor used for traction load work and a frequency converter used to provide the asynchronous motor with the required power supply voltage by changing the frequency of the power supply. [0003] When the load pulled by the asynchronous motor decelerates or stops, the inverter needs to brake the asynchronous motor. Among them, the over-excitation braking of the inverter is one of many inverter braking methods. At present, the over-excitation braking of the frequency converter is realized by increasing the given value of the excitation current of the stator of ...
Claims
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IPC IPC(8): H02P21/18H02P21/28H02P27/04
Inventor 陈振锋
Owner BOSCH REXROTH (XIAN) ELECTRIC DRIVES & CONTROLS CO LTD XIAN