Systems and methods for an on-board fast charger
View Patent ↗An innovative power electronic control system suitable for various applications, such as for electric vehicles is provided. The system, in some embodiments, is configured for the purposes of on-board AC fast charging (e.g., single phase or multi-phase) when an object is not in use (e.g., a vehicle is stationary) and use as a drive (e.g., for a vehicle, an EV drivetrain) when in motion. The innovative power electronic control system enables, among others, the ability to obtain fast-charging from existing grid infrastructure.
1. A method for operating an AC fast charger device, the method comprising:
provisioning gating signals for controlling operation of control operating characteristics of an AC/DC converter front-end circuit, a first traction inverter, and a second traction inverter that, when applied to one or more switching gates of the first traction inverter and the second traction inverter, shape an AC current flowing into the AC/DC converter front-end circuit from an AC power source and deliver power to a first energy storage device coupled to the first traction inverter and an electric motor and a second energy storage device coupled to the second traction inverter and the electric motor;
wherein the AC/DC converter front end circuit is an on-board rectifier connected across a differential connection of the first traction inverter and of the second traction inverter such that the first energy storage device and the second energy device are indirectly series connected through the first traction inverter and the second traction inverter and the motor; and
wherein the gating signals regulate a direction of power between at least one of the first energy storage device and the second energy device and the power source.
2. The method of claim 1 , wherein the gating signals cause interleaved switching of the one or more switching gates of the first traction inverter and the second traction inverter, the interleaved switching adapted to enable continuous conduction of the first energy storage device and the second energy storage device, the first energy storage device and the second energy storage conducting current through at least one phase of conduction in a period.
3. The method of claim 1 , wherein control of the direction of power flow and the power factor is conducted using current control circuits for each parallel phase such that each inductor current will track one third of an input current reference, the input current reference in each stator winding being a scaled version of a normalized rectified AC voltage.
4. The method of claim 1 , wherein each of the first traction inverter and the second traction inverter include a switching network incorporating the one or more switching gates, the switching networks controlling individual currents flowing to respective ones of the first energy storage device and the second energy storage device.
5. The method of claim 4 , wherein each of the switching networks of the first traction inverter and the second traction inverter include at least six switches having a set of inner switches and a set of outer switches.
6. The method of claim 5 , wherein the gating signals control the switching networks to balance power between the first energy storage device and the second energy storage device such that the voltage across the first energy storage device and the second energy storage device match an input voltage of the power source.
7. The method of claim 6 , wherein the gating signals between the switching network of the first traction inverter and the switching network of the second traction inverter are phase shifted by 180 degrees.
8. The method of claim 5 , wherein the set of inner switches and the set of outer switches have a same percentage of on-time in a switching period.
9. The method of claim 6 , wherein the gating signals between pairs of the switches of the switching networks are phase shifted by 120 degrees.
10. The method of claim 1 , wherein switches of the AC/DC converter front-end circuit are synchronized to a grid voltage of the power source.
11. The method of claim 1 , wherein the electric motor is mounted in a vehicle and the electric motor is configured for dual-mode operation comprising a first mode wherein the electric motor provides the drive functionality to impart forces to move the vehicle, and a second mode wherein the electric motor provides the charging functionality when electrically coupled to the power source.
12. The method of claim 1 , comprising generating control signals adapted to regulate a power factor on the grid-side and to reduce a magnitude of low frequency harmonics generated when charging a vehicle from the grid.
13. The method of claim 12 , comprising improving the power factor and reducing the harmonic current components generated at AC terminals of the converter thereby reducing the requirements for or eliminating an AC-side filter.
14. The method of claim 1 , wherein the power supply provides single-phase AC power.
15. The method of claim 1 , wherein the power supply provides three-phase AC power.
16. The method of claim 1 , wherein a net voltage across the first energy storage device and the second energy storage device is maintained by the controller circuit to always be greater than a peak voltage received from the power supply.
17. The method of claim 1 , wherein the shaping of the power characteristics of the power delivered to the first energy storage device and the second energy storage device from the power source is adapted to reduce waveform distortions in power imposed on the power source.
18. The method of claim 1 , wherein the shaping of the power characteristics of the power delivered to the first energy storage device and the second energy storage device from the power source shapes an inductor current reference such that it is in-phase with a rectified grid voltage when charging from a grid or inverted such that an average current is negative when sending power back to the grid.
19. An AC fast charger device adapted to provide both drive and charging functionality, the device comprising:
a first traction inverter and a first energy storage device coupled to an electric motor and to an AC power source;
a second traction inverter and a second energy storage device coupled to the electric motor and the AC power source, the first traction inverter and the second traction inverter coupled to one another across the electric motor;
an AC/DC converter front-end circuit interfacing the first traction inverter and the second traction inverter and the power source;
a controller circuit configured to control operating characteristics of the AC/DC converter front-end circuit, the first traction inverter, and the second traction inverter by provisioning gating signals that, when applied to one or more switching gates of the first traction inverter and the second traction inverter, shapes an AC current flowing into the AC/DC front-end circuit from the AC power source and delivers power to the first energy storage device and the second energy storage device; and
wherein the AC/DC converter front end circuit is an on-board rectifier connected across a differential connection of the first traction inverter and of the second traction inverter such that the first energy storage device and the second energy device are indirectly series connected through the first traction inverter and the second traction inverter and the motor; and
wherein the gating signals regulate a direction of power between at least one of the first energy storage device and the second energy device and the power source.
20. A non-transitory computer readable medium storing machine interpretable instruction sets, which when executed by a processor, cause the processor to perform a method for operating an AC fast charger device, the method comprising:
provisioning gating signals for controlling operation of control operating characteristics of an AC/DC converter front-end circuit, a first traction inverter, and a second traction inverter that, when applied to one or more switching gates of the first traction inverter and the second traction inverter, shape an AC current flowing into the AC/DC converter front-end circuit from an AC power source and deliver power to a first energy storage device coupled to the first traction inverter and an electric motor and a second energy storage device coupled to the second traction inverter and the electric motor;
wherein the AC/DC converter front end circuit is an on-board rectifier connected across a differential connection of the first traction inverter and of the second traction inverter such that the first energy storage device and the second energy device are indirectly series connected through the first traction inverter and the second traction inverter and the motor; and
wherein the gating signals regulate a direction of power between at least one of the first energy storage device and the second energy device and the power source.