Transformerless parallel AFE with ground current regulator
AssigneeRockwell Automation Technologies, Inc.
InventorsJames A. Ulrich, Lixiang Wei, Ahmed Mohamed Sayed Ahmed, Nickolay N. Guskov
Life of this patent
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Abstract
A transformerless parallel active rectifier system includes N multiphase common mode inductors directly connected to a shared multiphase AC input with no intervening transformer, and N active rectifiers coupled to respective ones of the N multiphase common mode inductors and having respective DC outputs coupled to a shared DC bus, where N is an integer greater than 1. The N active rectifiers have ground current regulators and are synchronized to provide DPWM switching control signals synchronized to one another to regulate their respective ground currents and concurrently regulate the shared DC bus voltage.
Claims20
A power conversion system, comprising:
- a first multiphase common mode inductor directly connected to a multiphase AC input;
- a first active rectifier having a first rectifier AC input, a first rectifier DC output, a first switch circuit, and a first controller, the first rectifier AC input coupled to the first multiphase common mode inductor, the first rectifier DC output having first and second DC nodes, the first switch circuit configured to selectively couple nodes of the first rectifier AC input to the first and second DC nodes according to first discontinuous pulse width modulation (DPWM) switching control signals, the first controller configured to generate the first DPWM switching control signals to regulate a first ground current of the first active rectifier and to regulate a DC bus voltage across the first and second DC nodes;
- a second multiphase common mode inductor directly connected to the multiphase AC input;
- and
- a second active rectifier having a second rectifier AC input, a second rectifier DC output, a second switch circuit, and a second controller, the second rectifier AC input coupled to the second multiphase common mode inductor, the second rectifier DC output coupled to the first rectifier DC output, the second switch circuit configured to selectively couple nodes of the second rectifier AC input to the first and second DC nodes according second DPWM rectifier switching control signals, the second controller configured to generate the second DPWM switching control signals to regulate a second ground current of the second active rectifier and to regulate the DC bus voltage.
An apparatus, comprising:
- a multiphase common mode inductor configured to be directly connected to a multiphase AC input;
- and
- an active rectifier having a rectifier AC input, a rectifier DC output, a switch circuit, and a controller, the rectifier AC input coupled to the multiphase common mode inductor, the rectifier DC output having first and second DC nodes, the switch circuit configured to selectively couple nodes of the rectifier AC input to the first and second DC nodes according to discontinuous pulse width modulation (DPWM) switching control signals, the controller configured to generate the DPWM switching control signals to regulate a ground current of the active rectifier and to regulate a DC bus voltage across the first and second DC nodes.
A method, comprising:
- sampling AC input phase currents of a rectifier AC input;
- computing a ground current of an active rectifier based on the AC input phase currents;
- computing a ground current regulator output based on the ground current to regulate the ground current;
- computing a DC bus regulator modulation index to regulate a DC bus voltage;
- computing an adjusted modulation index based on the DC bus regulator modulation index and the ground current regulator output to concurrently regulate the ground current and the DC bus voltage;
- and
- generating discontinuous pulse width modulation (DPWM) switching control signals to operate a switch circuit of the active rectifier based on the adjusted modulation index.
Dependencies are inferred from the claim text.