INDUCTIVE POWER TRANSFER SYSTEM AND METHOD FOR OPERATING AN INDUCTIVE POWER TRANSFER SYSTEM

• US 20150280455A1
• Filed: 03/30/2015
• Published: 10/01/2015
• Est. Priority Date: 03/31/2014
• Status: Active Grant

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: ABB Technology AG (ABB Limited)
• Inventors: KOLAR, Johann Walter, CANALES, Francisco, WUNSCH, Bernhard, BOSSHARD, Roman, GUGGISBERG, Beat, GONG, Guanghai
• Granted Patent: US 9,843,199 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60L 2210/10 DC to DC converters
• CPC Class Codes: B60L 2210/30 AC to DC converters
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 5/005 without mechanical contact between the collector and the power supply line
• CPC Class Codes: B60L 53/122 Circuits or methods for driving the primary coil, e.g. supplying electric power to the coil
• CPC Class Codes: B60L 53/126 Methods for pairing a vehicle and a charging station, e.g. establishing a one-to-one relation between a wireless power transmitter and a wireless power receiver
• CPC Class Codes: B60L 53/22 Constructional details or arrangements of charging converters specially adapted for charging electric vehicles
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/00712 the cycle being controlled or terminated in response to electric parameters
• CPC Class Codes: H02M 1/0054 Transistor switching losses periodically suspending operation of switching converter in low power mode H02M1/0035
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 3/3376 with automatic control of output voltage or current
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y02T 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles

Abstract

An exemplary inductive power transfer system having a transmitter coil and a receiver coil. A transmitter-side power converter having a mains rectifier stage powering a transmitter-side dc-bus and controlling a transmitter-side dc-bus voltage U_1,dc. A transmitter-side inverter stage with a switching frequency f_sw supplies the transmitter coil with an alternating current. A receiver-side power converter having a receiver-side rectifier stage that rectifies a voltage induced in the receiver coil and powering a receiver-side dc-bus and a receiver-side charging converter controlling a receiver-side dc-bus voltage U_2,dc. Power controllers that determine from a power transfer efficiency of the power transfer, reference values U_1,dc*, U_2,dc* for the transmitter and receiver side dc-bus voltages. An inverter stage switching controller controls the switching frequency f_sw to reduce losses in the transmitter-side inverter stage.

Claims

1. An inductive power transfer system for supplying electrical power from a transmitter-side subsystem connectable to a mains to a receiver-side subsystem connectable to a load, the system comprising:

a transmitter coil and a receiver coil;

a transmitter-side power converter including a mains rectifier stage to power a transmitter-side dc-bus and arranged to control a transmitter-side dc-bus voltage U_1,dc according to a corresponding reference value U_1,dc*;

a transmitter-side inverter stage with a controllable turn-off time of switches of the transmitter-side inverter stage to supply the transmitter coil with an alternating current;

a receiver-side power converter having a receiver-side rectifier stage to rectify a voltage induced in the receiver coil and to power a receiver-side dc-bus and a receiver-side charging converter arranged to control a receiver-side dc-bus voltage U_2,dc according to a corresponding reference value U_2,dc*;

one or more power controllers arranged to determine a value that is indicative of a power transfer efficiency of the power transfer and to calculate, from this value indicative of the power transfer efficiency, the reference values U_1,dc*, U_2,dc* for the transmitter-side dc-bus voltage U_1,dc and the receiver-side dc-bus voltage U_2,dc; and

an inverter stage switching controller arranged to control the turn-off time of the switches of the transmitter-side inverter stage to at least minimize switching losses in the transmitter-side inverter stage.

2. The inductive power transfer system of claim 1, comprising:

a communication channel for transmitting the reference value U_1,dc* for the transmitter-side dc-bus voltage U_1,dc from the receiver-side subsystem to the transmitter-side subsystem.

3. The inductive power transfer system of claim 1, wherein the value that is indicative of the power transfer efficiency is a magnetic coupling k between the transmitter coil and receiver coil.

4. The inductive power transfer system of claim 1, wherein the value indicative of the power transfer efficiency is computed from a measurement of an input power P_in input into the transmitter-side inverter stage or the transmitter coil and a measurement of a received power P_out that is output by the receiver coil or the receiver-side rectifier stage.

5. The inductive power transfer system of claim 1, wherein at least one of the reference values U_1,dc*, U_2,dc* for the transmitter-side dc-bus voltage U_1,dc and the receiver-side dc-bus voltage U_2,dc is determined from a look-up table wherein reference values obtained from an off-line calculation are stored as a function of transmitter and receiver coil currents and a switching frequency f_sw of the transmitter-side inverter stage.

6. The inductive power transfer system of claim 1, wherein the one or more power controllers are configured to compute the reference value U_2,dc* for the receiver-side dc-bus voltage U_2,dc from a measured difference between a load current I_batt. and a reference value I_batt* for the load current;

and to compute the reference value U_1,dc* for the transmitter-side dc-bus voltage U_1,dc from the reference value I_batt* for the load current and a measured value of the load voltage U_batt.

7. The inductive power transfer system of claim 2, wherein the value that is indicative of the power transfer efficiency is a magnetic coupling k between the transmitter coil and receiver coil.

8. The inductive power transfer system of claim 2, wherein the value indicative of the power transfer efficiency is computed from a measurement of an input power P_in input into the transmitter-side inverter stage or the transmitter coil and a measurement of a received power P_out that is output by the receiver coil or the receiver-side rectifier stage.

9. The inductive power transfer system of claim 2, wherein at least one of the reference values U_1,dc*, U_2,dc* for the transmitter-side dc-bus voltage U_1,dc and the receiver-side dc-bus voltage U_2,dc is determined from a look-up table wherein reference values obtained from an off-line calculation are stored as a function of transmitter and receiver coil currents and a switching frequency f_sw of the transmitter-side inverter stage.

10. The inductive power transfer system of claim 2, wherein the one or more power controllers are configured to compute the reference value U_2,dc* for the receiver-side dc-bus voltage U_2,dc from a measured difference between a load current I_batt. and a reference value I_batt* for the load current;

and to compute the reference value U_1,dc* for the transmitter-side dc-bus voltage U_1,dc from the reference value I_batt* for the load current and a measured value of the load voltage U_batt.

11. The inductive power transfer system of claim 1, wherein the inverter stage switching controller is arranged to control the transmitter-side inverter stage in an inductive region close to the resonant frequency f₀ of the transmitter for a switch-off current i_1,off, corresponding to a value of the transmitter coil current i₁(t) at the time of commutation, that is at a value that minimizes a switching loss of the transmitter-side inverter stage.

12. The inductive power transfer system of claim 1, wherein the inverter stage switching controller is arranged to control the turn-off time of the switches of the transmitter-side inverter stage for a switch-off current i_1,off to follow a switch-off current reference value.

13. The inductive power transfer system of claim 1, wherein the inverter stage switching controller is arranged to estimate a power loss in the semiconductor switches of the transmitter-side inverter stage and to perform an iterative search procedure, varying the turn-off time of the switches of the transmitter-side inverter stage to minimize the power loss.

14. The inductive power transfer system of claim 1, wherein the inverter stage switching controller is arranged to control the turn-off time of the switches of the transmitter-side inverter stage for the transmitter coil current i₁(t) to have a constant phase shift relative to the output voltage u₁(t) of the transmitter-side inverter stage.

15. A transmitter side subsystem of an inductive power transfer system, connectable to a mains and being able to supply electrical power to a receiver-side subsystem, the transmitter side subsystem comprising:

a transmitter coil;

a transmitter-side power converter including a mains rectifier stage to power a transmitter-side dc-bus and arranged to control a transmitter-side dc-bus voltage U_1,dc according to a corresponding reference value U_1,dc*, and

a transmitter-side inverter stage with a controllable turn-off time of switches of the transmitter-side inverter stage to supply the transmitter coil with an alternating current;

transmitter-side communication means for receiving the reference value U_1,dc* for the transmitter-side dc-bus voltage U_1,dc from the receiver-side subsystem; and

an inverter stage switching controller arranged to control the turn-off time of the switches of the transmitter-side inverter stage to at least minimize switching losses in the transmitter-side inverter stage transmitter-side inverter stag.

16. A receiver side subsystem of an inductive power transfer system, the receiver-side subsystem being connectable to a load and being able to receive electrical power from a transmitter-side subsystem, the receiver-side subsystem comprising:

a receiver coil;

a receiver-side power converter including a receiver-side rectifier stage to rectify a voltage induced in the receiver coil and to power a receiver-side dc-bus and a receiver-side charging converter arranged to control a receiver-side dc-bus voltage U_2,dc according to a corresponding reference value U_2,dc*;

a receiver-side controller arranged to determine a value that is indicative of a power transfer efficiency of the power transfer and to calculate, from this value indicative of the power transfer efficiency, reference values U_1,dc*, U_2,dc* for a transmitter-side dc-bus voltage U_1,dc and the receiver-side dc-bus voltage U_2,dc; and

receiver-side communication means for transmitting the reference value U_1,dc* for the transmitter-side dc-bus voltage U_1,dc from the receiver-side subsystem to the transmitter-side subsystem.

17. A method for controlling an inductive power transfer system for supplying electrical power from a transmitter-side subsystem connectable to a mains to a receiver-side subsystem that is connectable to a load, the inductive power transfer system that includes:

a transmitter coil and a receiver coil;

a transmitter-side power converter having a mains rectifier stage to power a transmitter-side dc-bus;

a transmitter-side inverter stage with a controllable turn-off time of switches of the transmitter-side inverter stage to supply the transmitter coil with an alternating current; and

a receiver-side power converter including a receiver-side rectifier stage to rectify a voltage induced in the receiver coil and to power a receiver-side dc-bus and a receiver-side charging converter arranged to control a receiver-side dc-bus voltage U_2,dc according to a corresponding reference value U_2,dc*;

the method comprising the steps of;

determining a value that is indicative of a power transfer efficiency of the power transfer and calculating, from this value indicative of the power transfer efficiency, reference values U_1,dc*, U_2,dc* for a transmitter-side dc-bus voltage U_1,dc and a receiver-side dc-bus voltage U_2,dc;

controlling the mains rectifier stage for the transmitter-side dc-bus voltage U_1,dc of the transmitter-side dc-bus to follow the corresponding reference value U_1,dc*;

controlling the receiver-side charging converter for the receiver-side dc-bus voltage U_2,dc of the receiver-side dc-bus to follow the corresponding reference value U_2,dc*, and

controlling the turn-off time of the switches of the transmitter-side inverter stage to at least minimize switching losses in the transmitter-side inverter stage transmitter-side inverter stage.