# US 10,771,229 B2 · Synchronizing method and system

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- Number: US 10,771,229 B2
- Document ID: US10771229B2
- Status: Granted
- Kind: B2
- Application number: 16/556,013
- Filed: 2019-08-29
- Published: 2020-03-05
- Granted: 2020-09-08
- Earliest claimed: 2018-08-30
- Assignees: Thales
- Applicants: Thales
- Inventors: Damian Andrade Alfonseca; Tony Teixeira; Stéphane Guguen
- Web page: https://patentgrep.com/patent/US10771229B2

## CPC

- H04L 7/0016: {correction of synchronization errors}
- H04L 12/403: with centralised control, e.g. polling
- H04L 7/08: the synchronisation signals recurring cyclically
- G05B 19/414: Structure of the control system, e.g. common controller or multiprocessor systems, interface to servo, programmable interface controller
- H04J 3/0641: {Change of the master or reference, e.g. take-over or failure of the master}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G)
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)

## Abstract

Method and system for synchronizing a plurality of pieces of equipment, wherein it includes at least the following steps: in each equipment generating the command signal, computing a value of the difference ΔH between a reference-clock value Hm and the local clock Hi of an equipment, on detecting a phase shift ΔH between the reference-clock value and the value of a local clock, when the value of the phase shift ΔH between the local clock and the reference clock corresponds to one refresh cycle of the reference clock Hm, a corrected clock time Hic is defined by repeating a number of the clock signal of given parity if the value of the local clock is early and a corrected clock time is defined by skipping one number of the clock signal of opposite parity to the first parity if the local clock value is late, when the value of the phase shift ΔH is higher than one refresh cycle, the method resets the reference time, a corrected value of the clock in each equipment is used to emit the command signal.

## Claims

### Claim 1

A method for synchronizing a plurality of equipments EQi each comprising a clock Hi adjusted to a quartz-crystal oscillator, said equipments EQi communicating together using a communication protocol, the plurality of equipment being configured to deliver a command signal to a device, comprising at least the following steps for one synchronization cycle:
in each equipment generating the command signal, computing a value of the difference ΔH between a reference-clock value Hm and the local clock Hi of an equipment, by comparing the value of the clock signal at a given time for the equipment to the value of the clock signal for the reference clock,
on detecting a phase shift ΔH between the reference-clock value and the value of a local clock,
when the value of the phase shift ΔH between the local clock and the reference clock corresponds to one refresh cycle of the reference clock Hm, a corrected clock time Hic is defined by repeating a number of the clock signal of given parity if the value of the local clock is early and a corrected clock time is defined by skipping one number of the clock signal of opposite parity to the first parity if the local clock value is late,
when the value of the phase shift ΔH is higher than one refresh cycle, resetting the reference time,
then using a corrected value of the clock in each equipment to emit the command signal.

### Claim 2 (depends on 1)

The synchronizing method as claimed in claim 1, wherein an even or uneven parity that is preserved during one synchronization cycle is defined.

### Claim 3 (depends on 1)

The synchronizing method as claimed in claim 1, wherein the synchronization cycle is repeated with a frequency Fs defined in the following way:
F
S
=
MAX
⁡
(

F
SMIN

,

F
SMAX

)
where
F
SMAX
=
F
0
⁡
(
1
+
ɛ
1
)
-
F
1
⁡
(
1
-
ɛ
2
)
2
F
SMIN
=
F
0
⁡
(
1
-
ɛ
1
)
-
F
1
⁡
(
1
+
ɛ
2
)
2
FS=F0(ε1+ε2)/2 if the nominal frequency of the oscillators is identical,
if the error of the oscillators is also identical, a refresh period is Fs=F0×ε,
with F0 the frequency corresponding to an equipment emitting the reference clock, F1 the frequency of a slave equipment, and ε0 and ε1 the precision of the oscillator.

### Claim 4 (depends on 1)

The synchronizing method as claimed in claim 1, further comprising a calibrating step comprising the following steps:
when an equipment is incorporated into a network, said equipment sends a message M(EQi) containing an emission time T0 to the subscribers of the network,
when the equipment EQi that emitted the message M(EQi) again receives said message, it compares the time contained in said message and the local time and determines a propagation time of said message between itself and said equipment of the system,
the equipment that wants to join the network stores the one or more computed propagation times in order to communicate with the other of the plurality of equipments EQi (inverters) of the network.

### Claim 5 (depends on 1)

The synchronizing method as claimed in claim 1, wherein the reference clock Hm is emitted by one of the plurality of equipments EQi that is initially designated a master.

### Claim 6 (depends on 5)

The synchronizing method as claimed in claim 5, wherein, in case of loss of reception of the clock emitted by the master, another of the plurality of equipments EQi having the highest priority in the network adopts the role of master and uses its local clock as reference clock for the other of the plurality of equipments EQi.

### Claim 7 (depends on 1)

The synchronizing method as claimed in claim 1, wherein emitted command signal is a power delivered by a piece of inverter equipment adapted for delivering energy to a rotating electric machine.

### Claim 8 (depends on 1)

A system for synchronizing emission of data between a plurality of equipments EQi communicating together by means of a physical communication link, wherein each equipment comprises at least the following elements:
an emitter, a receiver, a counter adapted for counting local clock signals, a local clock,
a memory storing message propagation times, a processor configured for executing the steps of the method as claimed in claim 1,
one equipment being configured to play a role of master and to deliver a reference clock.

### Claim 9 (depends on 8)

The system as claimed in claim 8, wherein one equipment is an inverter adapted for delivering energy to a rotating electric machine.