Integrated rectifier-generator system for AC-to-DC conversion
View Patent ↗This disclosure relates AC-to-DC rectification and power flow control of electrical power generators. An integrated rectifier-generator AC-DC conversion circuit and system are disclosed for providing a regulated DC output. The integrated rectifier-generator AC-DC conversion circuit and system may include serially stacked passive and active rectifiers connected to multiple AC ports of an electrical power generator driven by mechanical energy captured by an energy harvester. The integrated rectifier-generator AC-DC conversion circuit and system may be configured to perform active ripple control and a maximum power tracking from the energy harvester by controlling a fraction of an overall power that flow through the active rectifier.
1. A rectifying circuit, comprising:
an active rectifier comprising a first AC input, a control input, and a first DC output;
a passive rectifier comprising a second AC input, and a second DC output serially stacked with the first DC output to form a combined DC output; and
a main controller configured to measure a voltage ripple in the second DC output and provide one or more control signals to the control input of the active rectifier to regulate an output characteristics of the first DC output by reducing a voltage ripple in the combined DC output using a ripple compensation circuitry when the active rectifier and the passive rectifier are connected to a first AC source and a second AC source via the first AC input and the second AC input, respectively.
2. The rectifying circuit of claim 1 , wherein the ripple compensation circuit is configured to provide the one or more control signals to the control input of the active rectifier to generate a voltage ripple in the first DC output having identical amplitude and opposite phase of the measured voltage ripple in the second DC output.
3. The rectifying circuit of claim 1 , wherein:
the first AC input of the active rectifier comprises a plurality of AC components of different relevant phases; and
the control input of the active rectifier comprises a plurality of control ports corresponding to the plurality of AC components for regulating a superposition of the plurality of AC components to form the first DC output.
4. The rectifying circuit of claim 3 , wherein:
the active rectifier further comprises a plurality of power switches between the plurality of AC components and the first DC output; and
the one or more control signals from the main controller comprises a plurality of control signals for controlling each of the plurality of power switches to connect a corresponding AC component of the plurality of AC components to the first DC output or disconnecting the corresponding AC component from the first DC output for regulating the superposition of the plurality of AC components to form the first DC output.
5. The rectifying circuit of claim 1 , wherein the ripple compensation circuit is configured to generate control signals for the active rectifier to modulate the first DC output in voltage such that the first DC output compensates the voltage ripple in the second DC output and thus reduce the voltage ripple in the combined DC output.
6. The rectifying circuit of claim 5 , wherein the ripple compensation circuit comprises:
a reference voltage filter to derive a reference ripple voltage in accordance with a voltage of the second DC output; and
a ripple compensator to derive a perturbation d-axis current in accordance with the reference ripple voltage and a feedback ripple voltage, the ripple compensator further providing the control signals to the active rectifier to control the first DC output in voltage.
7. The rectifying circuit of claim 5 , wherein the ripple compensation circuit comprises:
a voltage controller configured to monitor a current voltage ripple in the second DC output to derive a target ripple compensating current value for the active rectifier;
a current controller configured to derive a target ripple compensating voltage value for the active rectifier based on the target ripple compensating current value and a currently monitored current of the active rectifier; and
a control signal generator configured to convert the target ripple compensating voltage value into the one or more control signals.
8. The rectifying circuit of claim 1 , further comprising an additional passive rectifier comprising a third AC input and a third DC output serially stacked with the first DC output and the second DC output to form the combined DC output.
9. The rectifying circuit of claim 8 , wherein:
the second AC input comprises a first plurality of AC components having different relative phases;
the third AC input comprises a second plurality of AC components having different relative phases; and
the first plurality of AC components and the second plurality of AC components have different relative phases.
10. The rectifying circuit of claim 1 , wherein:
the first AC input and the second AC input are provided from an electrical generator driven by an energy harvester; and
the main controller comprises a maximum power tracking circuit configured to control a power flow in the active rectifier to track maximum power extraction by the energy harvester.
11. The rectifying circuit of claim 10 , wherein the maximum power tracking circuit is configured to control the power flow of the active rectifier to derive a maximum power which could be harvested from the energy harvester by tracking an optimal rotational speed of the electrical generator based on a predetermined maximum power point tracking algorithm.
12. The rectifying circuit of claim 11 , wherein the energy harvester comprises a wind turbine.
13. A rectifying circuit, comprising:
an active rectifier comprising a first AC input, a control input, and a first DC output;
a passive rectifier comprising a second AC input, and a second DC output serially stacked with the first DC output to form a combined DC output; and
a main controller configured to provide one or more control signals to the control input of the active rectifier to regulate an output characteristics of the first DC output when the active rectifier and the passive rectifier are connected to a first AC source and a second AC source via the first AC input and the second AC input, respectively,
wherein:
the first AC input and the second AC input are provided from an electrical generator driven by an energy harvester;
the main controller comprises a maximum power tracking circuit configured to control a power flow in the active rectifier to track maximum power extraction by the energy harvester; and
the maximum power tracking circuit comprises:
a power controller configured to monitor a current rotational speed of the electrical generator and to derive a target current value for the active rectifier based on the predetermined maximum power point tracking algorithm;
a current controller configured to derive a target voltage value for the active rectifier based on the target current value and a currently monitored current of the active rectifier; and
a control signal generator configured to convert the target voltage value into the one or more control signals.
14. The rectifying circuit of claim 13 , wherein:
the power controller comprises a first proportional integral controller with a first set of pre-tuned proportional and integral gains; and
the current controller comprising a second proportional integral controller with a second set of pre-tuned proportional and integral gains.
15. An integrated rectifier-generator AC-DC conversion system, comprising:
a rectifying circuit, comprising:
an active rectifier comprising a first AC input, a control input, and a first DC output;
a passive rectifier comprising a second AC input, and a second DC output serially stacked with the first DC output to form a combined DC output; and
a main controller configured to measure a voltage ripple in the second DC output and provide one or more control signals to the control input of the active rectifier to regulate an output characteristics of the first DC output by reducing a voltage ripple in the combined DC output using a ripple compensation circuitry when the active rectifier and the passive rectifier is connected to a first AC source and a second AC source via the first AC input and the second AC input, respectively; and
an AC electrical generator comprising a first AC output and a second AC output connected to the first AC input of the active rectifier and the second AC input of the passive rectifier, respectively.
16. The integrated rectifier-generator AC-DC conversion system of claim 15 , wherein the AC electric generator comprises a multi-port permanent-magnet synchronous generator.
17. The integrated rectifier-generator AC-DC conversion system of claim 15 , wherein:
the first AC input and the second AC input are provided from an electrical generator driven by an energy harvester; and
the main controller comprises a maximum power tracking circuit configured to control a power flow in the active rectifier to track maximum power extraction by the energy harvester.
18. The integrated rectifier-generator AC-DC conversion system of claim 17 , wherein maximum power tracking circuit is configured to control the power flow of the active rectifier to derive a maximum power which could be harvested from the energy harvester by tracking an optimal rotational speed of the electrical generator based on a predetermined maximum power point tracking algorithm.