Systems and Methods For Reducing Circulating Current and Phase to Phase Imbalance In A Parallel Modular Converter System

• US 20160094040A1
• Filed: 12/15/2014
• Published: 03/31/2016
• Est. Priority Date: 09/30/2014
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Krolak, Matthew J., Gao, Lijun, Liu, Shengyi
• Granted Patent: US 9,991,719 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G05B 19/0421 Multiprocessor system
• CPC Class Codes: H02J 4/00 Circuit arrangements for mains or distribution networks not specified as ac or dc
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 1/325 with means for allowing continuous operation despite a fault, i.e. fault tolerant converters
• CPC Class Codes: H02M 5/4585 having a rectifier with controlled elements
• CPC Class Codes: H02M 7/493 the static converters being arranged for operation in parallel
• CPC Class Codes: H02M 7/53873 with digital control

Abstract

A system and method for providing power to a vehicle with reduced circulating current and phase-top-phase imbalance is disclosed. The system can include a plurality of parallel module converter for prioritizing and allocating each electrical load to one or more parallel modular converter modules. The system can also comprise a load balancer to ensure that differences in the properties (e.g., impedance) of the parallel modular converter modules do not create circulating currents or phase-to-phase imbalances. The load balancer can monitor the outputs to the plurality of parallel modular converter modules and modify the inputs to equalize, synchronize, or both the outputs.

Claims

1. A system for powering a plurality of electrical loads, the system comprising:

a first parallel modular converter module, with an input and an output, to provide a first alternating current (AC) output;

a second parallel modular converter module, with an input and an output, to provide a second AC output; and

a load balancer connected to the input and the output of the first parallel modular converter module and the second parallel modular converter module,

wherein the load balancer compares the output from the first parallel modular converter module and the second parallel modular converter module, and

wherein the load balancer modifies the input to the first parallel modular converter module to equalize the output of the first parallel modular converter module with the output of the second parallel modular converter module.

2. The system of claim 1, further comprising:

a third parallel modular converter module, with an input and an output, to provide a third alternating current (AC) output,

wherein the load balancer compares an output current of the output from the first parallel modular converter module, the second parallel modular converter module, and the third parallel modular converter module, and

wherein the load balancer modifies the input for one or more of the first parallel modular converter module, the second parallel modular converter module, and the third parallel modular converter module such that the output current of the first parallel modular converter module, the second parallel modular converter module, and the third parallel modular converter module are substantially balanced.

3. The system of claim 1, wherein the load balancer comprises a proportional-integral-derivative (PID) controller.

4. The system of claim 3, wherein an error for the PID controller comprises a difference between an output current from the first parallel modular converter module and the second parallel modular converter module, and

wherein the PID controller modifies the input to the first parallel modular converter module, the second parallel modular converter module, or both to reduce the error.

5. A parallel module converter comprising:

a first parallel modular converter module to provide a first alternating current (AC) output and connected to a module communications bus;

a second parallel modular converter module to provide a second AC output and connected to the module communications bus;

a master logic controller to assign a first load to one or more of the first parallel modular converter module and the second parallel modular converter module, the module communications bus connecting the first parallel modular converter module and the second parallel modular converter module;

a master communications controller connected to the module communications bus and the master logic controller to route messages therebetween; and

a load balancer connected to an input and an output of both the first parallel modular converter module and the second parallel modular converter module.

6. The parallel module converter of claim 5, wherein the master logic controller places the first parallel modular converter module and the second parallel modular converter module in parallel using a power switching network and assigns the first load to the first parallel modular converter module and the second parallel modular converter module;

and

wherein the load balancer modifies the input to the first parallel modular converter module to equalize the output of the first parallel modular converter module with the output of the second parallel modular converter module.

7. The parallel module converter of claim 6, further comprising:

a third parallel modular converter module to provide a third AC output signal and connected to the module communications bus,

wherein the master logic controller places the first parallel modular converter module, the second parallel modular converter module, and the third parallel modular converter module in parallel using the power switching network and assigns the first load to the first parallel modular converter module, the second parallel modular converter module, and the third parallel modular converter module, and

wherein the load balancer modifies the input to one or more of the first parallel modular converter module, the second parallel modular converter module, and the third parallel modular converter module to equalize the output of the first parallel modular converter module, the second parallel modular converter module, and the third parallel modular converter module.

8. The parallel module converter of claim 7, wherein the load balancer modifies a motor control algorithm for one or more of the first parallel modular converter module, the second parallel modular converter module, and the third parallel modular converter module such that an output current of the first parallel modular converter module, the second parallel modular converter module, and the third parallel modular converter module are substantially balanced.

9. The parallel module converter of claim 8, wherein the motor control algorithm comprises a field oriented control algorithm and the load balancer modifies a pulse width modulation (PWM) signal for one or more of the first parallel modular converter module, the second parallel modular converter module, and the third parallel modular converter module.

10. The parallel module converter of claim 5, further comprising:

a motor control system for providing one or more motor control algorithms to the first parallel modular converter module and the second parallel modular converter module; and

a control switching network for connecting the one or more motor control algorithms to the first parallel modular converter module and the second parallel modular converter module,

wherein the input for the first parallel modular converter module and the second parallel modular converter module is the one or more motor control algorithms, and

wherein the output for the first parallel modular converter module and the second parallel modular converter module is one or more output currents.

11. A method for balancing outputs between a plurality of parallel modular converter modules, the method comprising:

receiving a request to power a first load from a vehicle controller at a system controller;

calculating a number of parallel modular converter modules required to power the first load with a load balancer;

placing the calculated parallel modular converter modules required to power the first load in parallel with a master logic controller;

sensing an output from each of the calculated parallel modular converter modules with the load balancer; and

modifying an input signal to one or more of the calculated parallel modular converter modules with the load balancer such that the output of each of the calculated parallel modular converter modules is equal.

12. The method of claim 11, further comprising:

calculating an ideal load for each of the calculated parallel modular converter modules with the load balancer; and

modifying an input motor signal to one or more of the calculated parallel modular converter modules such that the output of each of the calculated parallel modular converter modules is substantially equal to the calculated ideal load.

13. The method of claim 12, wherein modifying the input signal comprises modifying a motor control algorithm to one or more of the calculated parallel modular converter modules such that output currents for each of the calculated parallel modular converter modules are synchronized.

14. The method of claim 13, wherein the motor control algorithm comprises a field-oriented-control (FOC) algorithm, and

wherein modifying the input motor control algorithms to one or more of the calculated parallel modular converter modules comprises modifying a pulse width modulation (PWM) signal of the FOC algorithm to substantially balance the output current between the calculated parallel modular converter modules.

15. The method of claim 13, wherein the motor control algorithm comprises a voltage over frequency control algorithm.

16. The method of claim 11, wherein modifying the input signal to one or more of the calculated parallel modular converter modules with the load balancer comprises modifying the input signal with a proportional-integral-derivative (PID) controller.

17. The method of claim 16, wherein an error for the PID controller comprises a difference between an output current from the calculated parallel modular converter modules, and

wherein modifying the input signal to one or more of the calculated parallel modular converter modules with the load balancer comprises the PID controller modifying the input to one or more of the calculated parallel modular converter modules to reduce the error.

18. The method of claim 11, further comprising:

calculating an ideal load between the calculated parallel modular converter modules required to power the first load with the load balancer; and

modifying the input signal to one or more of the calculated parallel modular converter modules with the load balancer such that the output of each of the calculated parallel modular converter modules is approximately equal to the ideal load.

19. The method of claim 18, wherein the load balancer comprises a PID controller,

wherein an error for the PID controller comprises a difference between an output current from each of the calculated parallel modular converter modules and the ideal load, and

wherein modifying the input signal to one or more of the calculated parallel modular converter modules with the load balancer comprises the PID controller modifying the input one or more of the calculated parallel modular converter modules to reduce the error.

20. The method of claim 11, further comprising:

providing one or more motor control algorithms to the calculated parallel modular converter modules, and

wherein modifying the input signal to one or more of the calculated parallel modular converter modules with the load balancer comprises modifying the one or more motor control algorithms.