WO2016079400A1 - Method for controlling electrical load by pulse width modulation - Google Patents

Abstract

The present invention relates to a system for controlling at least one electrical load (3 to 7) by pulse width modulation, comprising a chopper block (2) that modulates the supply voltage, having frames which each comprise a first sequence of N pulses including the binary states E_i,l correspondent to a word of N bits, and a second sequence of N pulses including the binary states E_i,2 corresponding to the word of N complementary bits, the system further comprising a two-wire supply line common to all the supplied loads, and at least one load (4 to 6) controlled by slave circuits (7 to 9). The invention also relates to a control method, a master controller and a slave controller for implementing the control process.

Description

 METHOD FOR CONTROLLING ELECTRICAL CHARGE BY MODULATION

 WIDTH OF PULSES.

Field of the invention

The present invention relates to the field of communication on a continuous supply line, for example to control electrical equipment, including light sources, on a common continuous supply line.

 The general principle consists in applying a succession of discrete states according to the technique known as Pulse Width Modulation (PWM).

 The communication is performed monodirectionally between a master device and one or more slave devices arranged on the power supply network. In particular, the communication channel can be used to control individually (turn on, off, adjust intensity) the lighting equipment arranged on the network, including LED modules.

 The pulse width modulation makes it possible, among other things, to adjust the brightness of electroluminescent diodes (35) when it is associated with a standard power supply. The constant input voltage is transformed into a rectangular voltage with an adjustable pulse / pause ratio (duty cycle ratio and duration of a period) using an PWM electronic circuit.

It is possible to specifically control several loads, in particular LEDs on the same power line by associating each load with a filtering circuit. State of the art

It is known in the state of the art the international patent application WO2007104154 which describes a controller circuit whose output controls the digital input of a [single] load, in order to control its activation. This tour includes:

 a) means for obtaining a desired activation ratio for a predetermined period of time, the activation rate representative of a time period ON of the electronic device with respect to the predetermined period of time;

 (b) means for determining an activation sequence for the electronic device, the activation sequence having two or more periods of activation time and one or more periods of deactivation time, wherein the two or more periods of time activation time with respect to the predetermined period of time is equivalent to the ratio activation.

Disadvantages of prior art

Some solutions of the prior art require the installation of an electrical control wire. In some cases of application, the use of a dedicated wired link is not desirable for practical and / or economic reasons, particularly when it comes to adapting an existing lighting system for which a new wiring will be required to integrate the communication wire (s) between the controller (master) and the lighting equipment (slaves). In this case, the addition of additional wires may be difficult (buried cabling) or unsightly (apparent cabling).

The implementation of a radiofrequency or carrier communication may then be an alternative. However, the The cost of such a solution can be high or even prohibitive when the slave equipment is numerous, each of them having to have its own radio frequency receiver or carrier currents.

 Some solutions of the prior art of power line control are also likely to cause a flickering (English flickering) perceptible brightness of light sources, due to the modulation of the power supply. Retinal relevance does not completely ignore this unpleasant phenomenon which, even if it remains subliminal, that is to say below the level of consciousness, can produce eye fatigue, irritation, and discomfort or even headaches. Solution provided by the invention

In order to meet these drawbacks, the invention relates, according to its most general meaning, to a control method according to claim 1.

Advantageously, each frame comprises a first sequence of N pulses whose binary states E _lfl correspond to word of N bits, and a second sequence of N pulses whose binary states E _lf2 correspond to the word of N complementary bits.

 According to this method, the energy of a frame is constant, whatever the information to be transmitted. The pulse trains coding the information thus do not cause any effects perceptible to the human eye on the light emitted by the lighting equipment connected to the supply network (notably, absence of flutter)

 Preferably, the level of said bit states is either the nominal supply value or the zero value.

This solution makes it possible to chop the supply voltage in a very simple way, with the aid of a transistor for example, avoiding the superposition on the continuous signal of a control signal, producing sensitivities to parasitic disturbances affecting the supply voltage.

 Preferably, the duration of a frame is less than 10 milliseconds.

 Advantageously, the feed is chopped continuously, including in the absence of information to be transmitted, and in that each of the sequences comprises at least one pulse in a state "1" and one pulse in a state "0" .

 According to a first variant, the frame generated in response to information to be transmitted is replicated until a new piece of information is transmitted. This solution makes it possible to use the periods during which no new information is transmitted to create redundancy of the last information transmitted.

 According to a second variant, the frame generated in the absence of information to be transmitted is constituted by a non-significant frame. The term "non-significant frame" means a frame that does not correspond to any of the coded information that can be transmitted.

 This non-significant frame can be always the same, or randomly selected in a library of non-significant frames.

The invention also relates to a system for controlling at least one pulse width modulation electric charge comprising a chopper block for modulating the supply voltage with frames each comprising a first sequence of N pulses whose states binary E _lfl correspond to word of N bits, and a second sequence of N pulses whose binary states E _lf2 correspond to the word of N complementary bits, the system further comprising a two-wire power supply line common to all the loads supplied, and at least one load controlled via slave circuits. The invention also relates to a circuit for controlling electric charges with frames each comprising a first sequence of N pulses whose binary states E _lfl correspond to word of N bits, and a second sequence of N pulses whose binary states E _lf2 correspond to at the word of N additional bits.

Advantageously, this electric charge control circuit comprises a power supply unit, responsible for supplying the necessary operating voltage to the microcontroller unit, from the supply voltage of the primary source, a microcontroller block, responsible for generating the data to be transmitted. in baseband on the power supply network, to slave controllers, and a chopper block, controlled directly by the output signal of a UART of the microcontroller, in order to reproduce on the power supply network the waveform frames transmitted by said UART. According to a variant, it further comprises a communication interface block, responsible for exchanging data between a computer and the microcontroller, for real-time control or for programming the master controller, for example by means of a USB connection.

As such, the control circuit advantageously comprises a converter block between a computer-> UART communication means, responsible for presenting the data transiting on the computer communication means into data that can be used by the UART input of the microcontroller and that the chopper block is controlled directly by the output signal of the UART, in order to reproduce on the power network the waveform of the frames transmitted by the UART. This computer communication means may be of the USB type, or Bluetooth or more generally any wired communication mode, radiofrequency, infrared, optical or other. The invention also relates to a slave controller for controlling a load supplied by a two-wire power line, characterized in that it comprises a power supply unit, a microcontroller unit, equipped with a UART type interface, whose function is to receive and analyze the coded data in the form of frames each comprising a first sequence of N pulses whose bit states E _lfl correspond to word of N bits, and a second sequence of N pulses whose binary states E _lf2 correspond at the word of N additional bits, the slave controller further comprising a voltage level shifting block, making it possible to make the nominal voltage of the DC supply network compatible with the voltage levels acceptable by the UART input of the microcontroller unit, and a control block for controlling the electrical load connected to the slave controller. It can in particular be an LED control block, responsible for driving the LED modules from control signal in PWM.

 Preferably, the slave controller comprises a capacitor for smoothing and filtering the input voltage.

DETAILED DESCRIPTION OF A NON-LIMITATIVE EMBODIMENT The invention will be better understood on reading the description of a nonlimiting example of embodiment which follows, with reference to the appended drawings in which:

 FIG. 1 represents the architecture of an installation according to the invention

 FIG. 2 represents a schematic view of the coded power supply signal according to the invention

 FIG. 3 represents a schematic view of the master controller

FIG. 4 represents a schematic view of the slave controller The solution proposed by the present invention consists in transmitting coded information to slave devices (4 to 6) in baseband on the Very Low Voltage DC power supply network.

 A continuous power source (1) is chopped by a master circuit (2) described in more detail below.

As described in FIG. 1, the master equipment consists of:

 a UART (Universal Asynchronous Receiver Transmitter) type communication data generator block, of which only the transmission function is exploited because of the one-way character of the invention,

 - A chopper block (DC-DC converter), whose command is directly the output signal of the UART, to reproduce on the power network the waveform of the frames transmitted by the UART.

 Charges (3 to 6) are connected directly to the two-wire power supply line common to all loads. Some loads (4 to 6) are controlled via slave circuits (7 to 9) described in more detail below.

 Other loads (3) are not controlled and are fed directly.

The slave equipment (4 to 6) consists of:

a power supply, the function of which is to generate the supply voltage of the other blocks from that of the continuous supply network and to maintain this supply voltage during the period of emission of the symbols ( ^T s _Y mb) during which the voltage of the continuous supply network becomes nil intermittently,

a data processing block, equipped with a UART type interface, whose function is to receive and to analyze the data transmitted by the master controller on the TBT network,

 a voltage level shifter block (if necessary), making it possible to make the nominal voltage of the DC supply network compatible with the voltage levels acceptable by the UART input of the data processing block,

- a command block, responsible for executing the corresponding actions to the data transmitted by the master equipment. This block can perform a switch or dimmer function for lighting equipment (4, 5) located downstream of the slave equipment. (7, 8)

 A computer (10) transmits to the master circuit (2) the charge control information.

 The master equipment (2) is placed between the very low voltage voltage source (typically 12, 24 or 48 volts) and the power supply.

 The slave equipment and the lighting equipment (lamp, LED, etc.) (3 to 6) are connected to the supply network downstream of the controller (2).

 When the slave devices (7 to 9) perform lighting control functions (switching on, off, brightness adjustment), the corresponding lighting equipment is located downstream of the slave devices (4 to 6).

 In practice, the solution amounts to implementing pulse width modulation (PWM), conventionally used to vary the brightness of DC lighting equipment, but whose pulse shape makes it possible to code the information. to communicate.

At each MLI period, a symbol is transmitted. Each symbol consists of bits that assume a high state (nominal supply voltage) or a low state (zero voltage). Coded signals

The signal is hashed to form frames comprising two sequences of the same duration:

 A first encoded sequence formed by pulses in a "high" or "low" binary state

 A second sequence whose number of pulses is not necessarily the same as for the first sequence, the state of these pulses being calculated so that the cumulative duration of the pulses in the "high" state is equal the cumulative duration of the pulses of the first sequence in the low state. This second sequence may comprise only two pulses, one in the high state, of a duration equal to the cumulative duration of the pulses in the low state of the first sequence, and one pulse in the low state. , for a complementary duration.

 For asynchronous transmission, the frame may further comprise a "start" or "stop" synchronization signal before and / or after each of the two sequences.

 A synchronization top (start bit) indicates to the receiver, by a first downward transition of the signal in line, the beginning of a sequence.

 The receiver, at this top, starts its local clock, which marks the bit times in a relative isochronism with that with which the receiver creates the signal.

FIG. 2 represents a schematic view of the supply signals according to an exemplary implementation of the invention.

A symbol (12) is formed of a first sequence (13) and a second sequence (14) of the same durations, each formed by a succession of pulses in a binary state. In the example given, each sequence is encoded on eight bits. In order to avoid fluctuations in the energy transmitted during a frame, the two bytes (13, 14) are constituted so that the second corresponds to the complement of the first. U _name : nominal voltage of the primary source of supply TBT

^T frame ^: period of a frame (defined as the emission of a symbol followed by inter symbol time), equivalent to the PWM period

T _symb : duration of emission of a symbol

^T symb / ^T frame ^: quotient equivalent to the duty cycle of PWM, constant

 A symbol = two additional bytes transmitted consecutively.

 MLI's information coding is such that:

 the reduction in the power available on the supply network remains acceptable (typically, the reduction should be limited to a value of the order of 10 to 20% of the power available at the primary power source, or an equivalent duty cycle of 80 to 90%).

 pulse trains coding the information do not cause effects visible to the human eye on the light emitted by the lighting equipment connected to the supply network (in particular, no fluttering).

 The proposed solution guarantees the absence of visible effect by 3 complementary means:

 continuous flow: the transmission of information is carried out permanently; in the absence of new information to be transmitted to the slaves, the preceding information or filling symbols having no informative value are transmitted; Due to its redundancy character, the choice to re-transmit the information already transmitted has the advantage of mitigating the risk of non-reception of information in the event of a transmission or reception error (since the communication is monodirectional from the master to the slaves, it is not possible for slaves to acknowledge receipt of information).

- switching frequency: the frequency of the PWM is sufficiently high. Typically, for a light source only not having a remanence character (such as an LED), the frequency must be greater than 100 Hz.

 - Iso-energy of the symbols: all the transmitted symbols have the same energy in order to avoid variations of luminosity according to the content of the transmitted information; for this, each symbol consists of the information byte to be transmitted and its complementary value (examples: {0x00, OxFF}, {OxAA, 0x55} ...). Thus, for each symbol, the sum of the bits in the high state is equal to the sum of the bits in the low state. As a result, each symbol represents a transmitted power of 50%, regardless of the value of the symbol.

 The system can be set as follows:

- primary source of power:

rated voltage U _nom = 12 V

- emission period of symbols T _frame = 5 ms

- UART (in transmission for the master device, in reception for the slave devices) configures in 19200 baud mode, 8 bits of data, without parity, 1 stop bit (the parity bit is not necessary; being constituted of the value to be transmitted and its complementary value, an error detection can be set up on reception by comparing the 2 received bytes), ie T _symb = 1 ms approximately

 This preferred embodiment has the following advantages:

 - the 12 V voltage is widespread for TBT lighting networks;

 the transmission rate of 19200 baud equals a bit period of approximately 52 microseconds, which makes it possible to have a great tolerance when receiving the data, in the case where the electrical characteristics of the chopper and the network lead to times rise and fall of the transmitted signal relatively high (of the order of several microseconds or more than 10 microseconds);

the transmission speed of 19200 baud makes it possible to limit the chopping frequency of the chopper during the transmission of the symbols, and thus to limit switching losses which cause the chopper to heat up;

 the emission period of the symbols of 5 ms corresponds to an effective bit rate of 1600 bit / s (200 symbols transmitted per second, each symbol carrying 8 bits of information), which is conventionally sufficient to control equipment on a lighting network;

 - the transmission rate of 19200 baud, associated with a transmission period of 5 ms, makes it possible to conserve 90% of available power on the supply network (duration of a symbol = 1 ms, with energy efficiency of 50% , out of symbol time = 4 ms, with 100% energy efficiency).

 On the other hand, this preferred embodiment is well in line with the criteria for guaranteeing the absence of visual effect of the data transmission:

 1. continuous flow,

2. high switching frequency of 200 Hz (1 / T _frame ),

 3. symbol iso-energy: for each symbol, 2 low start bits, 2 high off bits, 8 low data bits, and 8 data bits at the low state. high state (guaranteed by the complementarity of the bytes transmitted).

 The high level corresponds to the rated voltage of the power supply. The low level may correspond to a zero voltage, or an intermediate voltage, for example 50% or 75% of the nominal voltage of the power supply.

Description of the master controller

Figure 3 shows a schematic view of the master controller (2). It comprises :

a USB-> UART converter block (20), responsible for presenting the data exchanged with the computer and transiting on the USB bus in data usable by the UART input of the microcontroller. - a power supply unit (22), responsible for supplying the necessary operating voltage to the microcontroller unit (23), from the supply voltage of the primary source (1);

 a microcontroller block (23), responsible for managing the communication with the computer, and generating the data to be transmitted in baseband on the supply network, to the slave controllers;

 - A chopper block (24), whose control is directly the output signal of the UART, to reproduce on the power network the waveform of the frames transmitted by the UART.

Description of the slave controller

As described in FIG. 4, the slave controllers (7 to 9) consist of an electronic circuit comprising:

 a power supply unit (30) whose function is to (1) generate the supply voltage of the other blocks from that of the continuous supply network and (2) maintain this supply voltage during the period for transmitting symbols during which the voltage of the continuous supply network becomes intermittently zero, in particular by the use of a buffer capacitor (34) associated with a diode (35),

 a microcontroller unit (32), equipped with a UART type interface, whose function is to receive and analyze the data transmitted by the controller on the TBT network, and a PWM type interface, of which the function is to adjust the brightness level of the LED modules.

 a voltage level shifter block (31), making it possible to make the nominal voltage of the DC supply network compatible with the voltage levels acceptable by the UART input of the microcontroller unit,

 - an LED control block (33), responsible for driving the LED modules from PWM control signal.

Claims

 claims 1 - Method for controlling at least one electrical charge by pulse width modulation, characterized in that each frame comprises a first sequence of N pulses whose binary states E _lfl correspond to N bits word, and a second sequence of M pulses, the cumulative duration of the pulses of the first sequence whose state corresponds to a first value V being equal to the cumulative duration of the pulses of the second sequence whose state corresponds to the complementary value of V. 2 - A method for controlling at least one pulse width modulation electric charge according to claim 1, characterized in that each frame comprises a first sequence of N pulses whose bit states E _lfl correspond to N bits word, and a second sequence of N pulses whose binary states E _lf2 correspond to the word of N complementary bits. 3 - Control method according to claim 1 or 2 characterized in that the level of said bit states is either the nominal power supply or the zero value. 4 - Control method according to at least one of the preceding claims characterized in that the duration of a frame is less than 10 milliseconds. 5 - control method according to at least one of the preceding claims characterized in that a frame further comprises a service signal before and / or after each sequence. 6 - Control method according to at least one of the preceding claims, characterized in that the power supply is chopped continuously, including in the absence of information to be transmitted, and in that each of the sequences comprises at least one pulse in a state "1" and one pulse in a state "0". 7 - Control method according to the preceding claim characterized in that the frame generated in response to information to be transmitted is replicated until the receipt of new information to be transmitted. 8 - Control method according to the preceding claim 6 in that the frame generated in the absence of information to be transmitted is constituted by a non-significant frame. 9 - System for controlling at least one electrical charge by pulse width modulation comprising a chopper block providing modulation of the supply voltage with frames each comprising a first sequence of N pulses whose binary states E _lfl correspond to in word of N bits, and a second sequence of M pulses, the cumulative duration of the pulses of the first sequence whose state corresponds to a first value V being equal to the cumulative duration of the pulses of the second sequence whose state corresponds to the complementary value of V. 10 - System for controlling at least one pulse width modulation electric charge comprising a chopper block providing the modulation of the supply voltage with frames each comprising a first sequence of N pulses whose binary states E _lfl correspond to N bits, and a second sequence of N pulses whose bit states E _lf2 correspond to the word of N complementary bits, the system further comprising a two-wire feed line common to all the feeds fed, and at least one charge (4 to 6) controlled via slave circuits (7 to 9). 11 - Electric charge control circuit with frames each comprising a first sequence of N pulses whose bit states E _lfl correspond to word of N bits, and a second sequence of N pulses whose binary states E ₁₂ correspond to the word of N complementary bits. 12 - electric charge control circuit according to claim 10 or 11 characterized in that it comprises a power supply unit (22), responsible for supplying the necessary operating voltage to the microcontroller unit (23), from the voltage of supplying the primary source, a microcontroller block (23), responsible for managing the communication with the computer, and generating the data to be transmitted in baseband on the power supply network, to slave controllers and a chopper block ( 24). 13 - Electric charge control circuit according to the preceding claim characterized in that it further comprises a converter block between a computer communication means> UART (20), responsible for presenting the data transiting on the computer communication means in data usable by the UART input of the microcontroller and in that the chopper unit (24) is directly controlled by the output signal of the UART, in order to reproduce on the power supply network the waveform of the frames transmitted by the UART. 14 - Slave controller for controlling a load (7 to 9) fed by a two-wire power line characterized in that it comprises a power supply unit (30), a microcontroller unit (32), equipped with a UART type interface, whose function is to receive and analyze the coded data in the form of frames each comprising a first sequence N pulses whose bit states E _lfl correspond to word of N bits, and a second sequence of M pulses, the cumulative duration of the pulses of the first sequence whose state corresponds to a first value V being equal to the cumulative duration of pulses of the second sequence whose state corresponds to the complementary value of V. 15 - Slave controller for controlling a load (7 to 9) powered by a two-wire power line characterized in that it comprises a power supply unit (30), a microcontroller unit (32), equipped with an interface of UART type, the function of which is to receive and analyze the coded data in the form of frames each comprising a first sequence of N pulses whose bit states E _lfl correspond to word of N bits, and a second sequence of N pulses whose bit states E _lf2 correspond to the word of N complementary bits, the slave controller further comprising a voltage level shift block (31), making it possible to make the nominal voltage of the continuous supply network compatible with the voltage levels acceptable by the UART input of the microcontroller block. 16 - Slave controller according to the preceding claim characterized in that it further comprises an LED control block (33), responsible for driving the LED modules from PWM control signal. 17 - Slave controller according to the preceding claim characterized in that it comprises a capacitor (34) associated with a diode (35) for smoothing and filtering the input voltage of the power supply unit (30). 18 - control method according to any one of the preceding claims in that the coded information is transmitted to slave devices (4 to 6) in a band of based on the supply network Very Low DC voltage supplied by a DC power source (1) minced by a master circuit (2) for controlling electrical equipment, including light sources, on a continuous supply line common.