Electric vehicle battery charger
A battery charger capable of receiving AC power and delivering both AC and DC power to an electric power storage battery in accordance to different embodiments disclosed herein using a rectifier circuit supplying the DC load and absorbing power as a five-level active rectifier with low harmonics on the AC input. In one aspect, the battery charger may have a bidirectional rectifier/inverter converter providing power conversion between a DC source and AC enabling the user to not only charge an electrical vehicle (“EV”) but also convert the energy charged in the EV/battery or solar panel to AC for use.
1. A battery charger for delivering power to an electric power storage battery, said battery charger comprising:
an AC input for receiving power from an electrical entry;
a battery charging controller interface for communicating with the electric power storage battery and receiving a charge voltage value;
a power converter connected to said AC input and responsive to said charge voltage value to convert power from said AC input to DC at a DC output at a variable voltage according to said charge voltage value for a DC load, said power converter comprising:
at least one high-voltage capacitor for storing power;
a rectifier circuit comprising:
an inductor connected in series with said AC input,
a low-voltage capacitor,
one of:
two diodes connected between a first AC input terminal and opposed ends of said high-voltage capacitor; and
two high-voltage switches connected between a first AC input terminal and opposed ends of said high-voltage capacitor,
two intermediate low-voltage power switches connected between said opposed end of said high-voltage capacitor and opposed ends of said low-voltage capacitor, and
two terminal low-voltage power switches connected between said opposed ends of said low-voltage capacitor and a second AC terminal,
wherein the DC load can be connected to said opposed ends of said high-voltage capacitor;
a controller having as input said charge voltage value, at least a phase reading from said AC input and a voltage of said at least one high-voltage capacitor, and having a reference signal output;
a modulator connected to said controller for receiving said reference signal and outputting comparison signals;
a state selection circuit for receiving said comparison signals and outputting state selection signals;
a switching pulse generator receiving said state selection signals and connected to one of:
when the power converter has said two diodes, gates of said power, gates of said power said two intermediate low-voltage power switches, said two terminal low-voltage power switches; and
when the power converter has said two high-voltage switches, gates of said power said two intermediate low-voltage power switches, said two terminal low-voltage power switches and said two high-voltage switches.
2. The charger as defined in claim 1 , further comprising at least one sensor connected to said modulator for sensing current and/or voltage in said rectifier circuit and connected to a gate input of said two intermediate low-voltage power switches and said two terminal low-voltage power switches.
3. The charger as defined in claim 1 , wherein said controller is operative for causing said rectifier circuit to operate in a boost mode wherein a voltage of said high voltage capacitor is higher than a peak voltage of said AC input, and said two intermediate low voltage power switches and said two terminal low voltage power switches are switched with redundant switching states in response to a measurement of a voltage present at said low voltage capacitor so as to maintain said low voltage capacitor at a predetermined fraction of a desired voltage for said high voltage capacitor and to thus maintain said high voltage capacitor at a desired high voltage, with said rectifier circuit supplying said DC load and absorbing power as a five-level active rectifier with low harmonics on said AC input.
4. The charger as defined in claim 1 , wherein said state selection module uses voltage between said the high-voltage capacitor and said the low-voltage capacitor to provide said state selection signals.
5. The charger as defined in claim 1 , wherein said battery charging controller interface further communicates with the electric power storage battery and receives a desired charge current value, and said power converter is further responsive to said desired charge current value to convert power from said AC input to DC at a DC output at a variable current not exceeding said desired charge current value for a DC load.
6. The charger as defined in claim 1 , further comprising a buck converter circuit for converting DC power from said opposed ends of said high-voltage capacitor to a lower DC output voltage set by said charge voltage value.
7. The charger as defined in claim 1 , further comprising a boost converter circuit for converting DC power from said opposed ends of said high-voltage capacitor to a higher DC output voltage set by said charge voltage value.
8. The charger as defined in claim 1 , wherein said two intermediate low-voltage power switches and said two terminal low-voltage power switches are switched at a frequency above 3 kHz.
9. The charger as defined in claim 1 , wherein said AC input is single phase and about 240 V RMS and said DC output power is at a voltage greater than 350 V.
10. The charger as defined in claim 1 , wherein said charger comprises a plurality of module connectors and at least one module connected in said module connectors, each of said modules comprising said rectifier circuit, said modules working in parallel to provide DC power to said load, wherein at least one of said two high-voltage switches, two intermediate low-voltage power switches and two terminal low-voltage power switches of said module are positioned at an edge of said module to be assembled on a heat sink providing required cooling for said at least one of said switches.
11. The charger as defined in claim 10 , wherein said high-voltage capacitor of each one of said modules is about 4 millifarads.
12. The charger as defined in claim 10 , wherein each one of said modules is able to supply more than about 2 kW of DC load power.
13. The charger as defined in claim 1 wherein said charger is able to supply more than 10 kW of DC load power.
14. The battery charger as defined in claim 1 wherein:
said rectifier circuit is a bidirectional rectifier/inverter circuit comprising an inductor connected in series with an AC port, a low-voltage capacitor, two high-voltage power switches connected between a first AC terminal and opposed ends of said high-voltage capacitor, two intermediate low-voltage power switches connected between said opposed end of said high-voltage capacitor and opposed ends of said low-voltage capacitor, and two terminal low-voltage power switches connected between said opposed ends of said low-voltage capacitor and a second AC terminal, wherein a DC port can be connected to said opposed ends of said high-voltage capacitor;
said controller is a first controller for a rectifier mode having at least one sensor for sensing current and/or voltage in said bidirectional rectifier/inverter and connected to a gate input of said two high-voltage power switches, said two intermediate low-voltage power switches and said two terminal low-voltage power switches for causing said rectifier circuit to operate in a boost mode wherein a voltage of said high-voltage capacitor is higher than a peak voltage of said AC input, and said two high-voltage power switches are controlled to switch on and off at a frequency of said AC input, and said two intermediate low-voltage power switches and said two terminal low-voltage power switches are switched with redundant switching states in response to a measurement of a voltage present at said low voltage capacitor so as to maintain said low voltage capacitor at a predetermined fraction of a desired voltage for said high-voltage capacitor and to thus maintain said high voltage capacitor at a desired high voltage, with said rectifier circuit supplying said DC load and absorbing power as a five-level active rectifier with low harmonics on said AC input; and
said power converter further comprises a second controller for an inverter mode connected to said two high-voltage power switches, said two intermediate low-voltage power switches and said two terminal low-voltage power switches and configured to generate and apply to said two high-voltage power switches, said two intermediate low-voltage power switches and said two terminal low-voltage power switches signal waveforms comprising a first control signal for causing said low-voltage capacitor to be series connected with said DC port and said AC port and charged to a predetermined value proportional to a Voltage of said DC port, and a second control signal for causing said low-voltage capacitor to be disconnected from the DC port and series connected with the AC port, thereby causing the low-voltage capacitor to be discharged.
15. A battery charger for delivering power to an electric power storage battery, said battery charger comprising:
an AC input for receiving AC power from an electrical entry;
a battery charging controller interface for communicating with the electric power storage battery and receiving a charge voltage value;
a power converter connected to said AC input and responsive to said charge voltage value to convert power from said AC input to DC at a DC output at a variable voltage according to said charge voltage value for a DC load, said power converter comprising:
at least one high-voltage capacitor for storing power at a voltage boosted above a peak voltage of said AC input;
a rectifier circuit comprising:
an inductor connected in series with said AC input,
a low-voltage capacitor,
two diodes connected between a first AC input terminal and opposed ends of said high-voltage capacitor; and
two intermediate low-voltage power switches connected between said opposed end of said high-voltage capacitor and opposed ends of said low-voltage capacitor, and
two terminal low-voltage power switches connected between said opposed ends of said low-voltage capacitor and a second AC terminal,
wherein the DC load can be connected to said opposed ends of said high-voltage capacitor; and
a controller having at least one sensor for sensing current and/or voltage in said rectifier circuit and connected to a gate input of said two intermediate low-voltage power switches and said two terminal low-voltage power switches.
16. The battery charger as defined in claim 15 , wherein said controller is operative for causing said rectifier circuit to operate in a boost mode wherein a voltage of said high-voltage capacitor is higher than a peak voltage of said AC input, and said two intermediate low-voltage power switches and said two terminal low-voltage power switches are switched with redundant switching states in response to a measurement of a voltage present at said low-voltage capacitor so as to maintain said low-voltage capacitor at a predetermined fraction of a desired voltage for said high-voltage capacitor and to thus maintain said high-voltage capacitor at a desired high voltage, with said rectifier circuit supplying said DC load and absorbing power as a five-level active rectifier with low harmonics on said AC input.
17. The charger as defined in claim 15 , wherein said battery charging controller interface further communicates with the electric power storage battery and receives a desired charge current value, and said power converter is further responsive to said desired charge current value to convert power from said AC input to DC at a DC output at a variable current not exceeding said desired charge current value for a DC load.
18. The charger as defined in claim 15 , further comprising a buck converter circuit for converting DC power from said opposed ends of said high-voltage capacitor to a lower DC output voltage set by said charge voltage value.
19. The charger as defined in claim 15 , further comprising a boost converter circuit for converting DC power from said opposed ends of said high-voltage capacitor to a higher DC output voltage set by said charge voltage value.
20. The charger as defined in claim 15 , wherein said charger comprises a plurality of module connectors and at least one module connected in said module connectors, each of said modules comprising said rectifier circuit, said modules working in parallel to provide DC power to said load, wherein at least one of said two high-voltage switches, two intermediate low-voltage power switches and two terminal low-voltage power switches of said module are positioned at an edge of said module to be assembled on a heat sink providing required cooling for said at least one of said switches.