WO2020099272A1

WO2020099272A1 - A wireless communication node arranged to operate in a wireless network, as well as a related method, for synchronizing power bursts during transmission of a message

Info

Publication number: WO2020099272A1
Application number: PCT/EP2019/080723
Authority: WO
Inventors: Matthias Wendt; Bernd Ackermann; Harald Josef Günther RADERMACHER
Original assignee: Signify Holding B.V.
Priority date: 2018-11-13
Filing date: 2019-11-08
Publication date: 2020-05-22

Abstract

The invention relates to a wireless communication node arranged to operate in a wireless network, wherein said wireless communication node is arranged for supplying power to an electrical load as well as arranged for wireless connectivity. The wireless communication node comprising a wireless communication unit for providing wireless connectivity, a switched mode power supply, arranged for supplying power to said electrical load and to said wireless communication unit, wherein said SMPS operates in accordance with a burst mode operation, wherein said SMPS is alternatively enabled and disabled and a controller arranged for ensuring that said SMPS is enabled when said wireless communication unit is to transmit a message.

Description

A WIRELESS COMMUNICATION NODE ARRANGED TO OPERATE IN A WIRELESS NETWORK, AS WELL AS A RELATED METHOD, FOR SYNCHRONIZING POWER BURSTS DURING TRANSMISSION OF A MESSAGE

BACKGROUND

In most connected lamps a single mains power supply is used for both the normal operation, i.e. when the lamp is emitting light, and for supplying standby power when the lamp is turned off and the wireless communication unit is listening or exchanging information. This is typically realized in a so called burst mode operation of a switched mode power supply. In such a burst mode operation, the switched mode power supply is alternatively enabled and disabled. When the switched mode power supply is disabled, no power is provided. The switched mode power supply is simply turned off. When the switched mode power supply is enabled, a power is supplied.

The switched mode power supply, SMPS, is an efficient supply for, for example, converting an AC mains input supply to a DC voltage. One possible example of a switched mode power supply is the so called flyback converter. Voltage regulation may be achieved by varying a duty cycle of the on and off states of the switch comprised by the flyback converter.

In, for example, WiFi systems, a fixed periodical time scheme is used to reduce power consumption and still keep nodes in the network of certain access points. Beacon frames are used by the access points to communicate throughout the serviced area the characteristics of the connection offered to the cell members. This information is used by clients trying to connect to the network. Here, beacons may be sent periodically at a time called Target Beacon Transmission Time, TBTT.

In, for example, ZigBee networks, beacon frames are periodically transmitted by the coordinators. They offer synchronization to the network and help identifying the network and its structure.

One of the issues with wireless communication nodes is that the Radio Frequency, RF, transmission typically consumes much more power than a pC standby operation, for example providing power to an electrical load.

SUMMARY

It would be advantageous to achieve a wireless communication node that is construed in such a way that the SMPS is controlled more efficient with respect to the different loads of the wireless communication node.

It would further be advantageous to achieve a corresponding method and computer program product.

The above mentioned and other objects are achieved in a first aspect of the present disclosure, by a wireless communication node arranged to operate in a wireless network, wherein said wireless communication node is arranged for supplying power to an electrical load as well as arranged for wireless connectivity.

The wireless communication node comprising:

a wireless communication unit for providing wireless connectivity;

a switched mode power supply, SMPS, arranged for supplying power to said electrical load and to said wireless communication unit, wherein said SMPS operates in accordance with a burst mode operation, wherein said SMPS is alternatively enabled and disabled;

a controller arranged for ensuring that said SMPS is enabled when said wireless communication unit is to transmit a message.

It was the insight of the inventors that it is advantageous that the switched mode power supply is in an enabled state whenever the wireless communication unit is to transmit a message. This is beneficial for the following reasons.

Typically, an output capacitor is connected to the SMPS for storing energy supplied by the SMPS. The energy stored by the output capacitor may be consumed by, for example, the electrical load.

It was noted that, typically, the wireless communication unit consumes much more power compared to the electrical load. As such, it may be beneficial to ensure that the SMPS is enabled when the wireless communication unit is to transmit a message. The power may then directly be provided by the SMPS instead of the output capacitor that is connected thereto, such that the dimensions of the output capacitor may be reduced.

In accordance with the present disclosure, the wireless communication node may be operative in a mesh network like a wireless Bluetooth mesh network. The wireless communication node may, for example, be an Internet of Things, IOT, device. The IOT device is, for example, directed to performing a measurement or anything a like, and to wirelessly transmit the measurement to the outside world. In accordance with the present disclosure, a SMPS may, preferably, be an isolated SMPS but may also be a non-isolated SMPS. A non-isolated SMPS is, for example, a buck converter. An isolated SMPS is, for example, a flyback converter.

In an example, the wireless communication node further comprises a lighting unit for providing light, and wherein said SMPS is arranged for supplying power to said lighting unit.

Here, the electrical load is construed by the lighting unit. The wireless communication node may thus be a lamp or anything alike, wherein the lamp also provides for wireless connectivity. For example, the lamp may be controlled using wireless commands.

In a further example, the SMPS is arranged to alternatively be enabled and disabled in accordance with a feedback voltage from said supplied power, wherein said power supply is enabled when said feedback voltage is below a first threshold, and wherein said power supply is disabled when said feedback voltage is above a second threshold, and wherein said controller is arranged to actively increase any of the first and the second threshold triggered by said wireless communication unit is to transmit said message.

As mentioned above, an output capacitor may be connected to the SMPS, wherein the output capacitor forms a buffer for providing power to the electrical load. The voltage over the output capacitor may be used as a feedback voltage for determining the burst mode characteristics. If the voltage over the output capacitor is below a first threshold, the SMPS may be enabled. If the voltage over the output capacitor is above a second threshold, the SMPS may be disabled. The second threshold value is higher than the first threshold value.

In other words, in the enabled mode, the output capacitor is charged until the voltage over the output capacitor is above the second threshold. Then, the SMPS is disabled, such that the power consumed by the wireless communication node is provided by the output capacitor, thereby draining the capacitor. The SMPS is then enabled again whenever the voltage over the output capacitor drops to below the first threshold, such that the capacitor is charged again. This cycle may be repeatedly performed over time.

In a further example, the controller is arranged to actively increase any of said first and second threshold triggered by said wireless communication unit stopping with transmitting said message. The controller may influence the moments in which the SMPS is enabled and disabled. To do so, the controller may actively increase any of the first and second threshold. Increasing the first threshold ensures that the SMPS will be enabled.

In a further example, the power supply is arranged for providing a trigger message to said controller thereby indicating that it is being enabled, and wherein said controller is arranged for activating said wireless communication unit for transmitting said message triggered by said received trigger message.

The inventors have found that at least two methods exist for ensuring that the SMPS is enabled whenever the wireless communication unit is to transmit a message. A first method is directed to the concept that the controller is actively instructing the SMPS to enable, as explained above. Another method is directed to the concept that the SMPS is actively making the controller aware of the fact that it is transitioning to the enabled mode.

The above may be accomplished using a trigger message, or a trigger signal, or an activation bit, or anything alike. The controller may use such a message, signal, bit, to start transmitting a particular message.

More specifically, whenever a particular message is to be transmitted, the controller may place such a particular message in a transmit queue. Each time the controller receives a trigger from the SMPS, the message(s) in the transmit queue may be actually transmitted. This ensures that the SMPS is actually enabled whenever a message is transmitted.

In a further example, the switch comprised by said SMPS is arranged to operate in accordance with a duty cycle when it is enabled, and wherein said controller is arranged to adapt said duty cycle when said wireless communication unit is to transmit said message.

The inventors have further noted that, during the enabled mode of the SMPS, the duty cycle of the switch comprised by the SMPS may be adapted. As mentioned above, during the enabled mode, the wireless communication unit may be active or not. It is not required that the wireless communication unit is actually transmitting a message each time the SMPS is enabled. The present disclosure is actually the other way around. It is ensured that the SMPS is enabled each time the wireless communication unit is to transmit a message.

Following the above, if the SMPS is enabled, then the wireless communication unit may transmit a message or not. If the wireless communication unit is to transmit a message, more power may be required from the SMPS compared to the situation that the wireless communication unit is not transmitting a message. As such, the duty cycle of the control signal of the switch comprised by the SMPS may be adapted to ensure that the SMPS is controlled efficiently.

In a further example, the SMPS is arranged to operate, when it is enabled, according to a standby burst mode setting or a wireless communication setting, wherein said setting indicates parameters for said SMPS, wherein said controller is arranged to set said SMPS to said wireless communication setting mode when said wireless communication unit is to transmit said message.

In a second aspect, there is provided a method of operating a wireless communication node in accordance with any of the previous examples, wherein said method comprises the steps of:

supplying, by said SMPS, power to said electrical load and to said wireless communication unit in accordance with a burst mode operation wherein said SMPS is alternatively enabled and disabled;

ensuring, by said controller, that said SMPS is enabled when said wireless communication unit is to transmit a message.

It is noted that the advantages and definitions as disclosed with respect to the embodiments of the first aspect of the invention also correspond to the embodiments of the second aspect of the invention, being the method of operating a wireless communication node.

In accordance with the present disclosure, the controller may be a Field Programmable Gate Array, a micro processor, or anything alike. The controller may also be implemented using analogue electronics / components.

In an example, the wireless communication node further comprises a lighting unit for providing light, and wherein said step of supplying power comprises:

supplying power to said lighting unit.

In a further example, the SMPS is arranged to alternatively be enabled and disabled in accordance with a feedback voltage from said supplied power, wherein said step of ensuring comprises:

enabling, by said controller, said SMPS when said feedback voltage is below a first threshold, and disabling, by said controller, said SMPS, when said feedback voltage is above a second threshold, and

actively increase, by said controller, any of the first and the second threshold triggered by said wireless communication unit is to transmit said message.

In a further example, the method further comprises the step of: actively increase, by said controller, an of said first and second threshold triggered by said wireless communication unit stopping with transmitting said message.

In yet another example, the method further comprises the step of: providing, by said SMPS, a trigger message to said controller thereby indicating that it is being enabled, and wherein said step of ensuring comprises:

activating, by said controller, said wireless communication unit for transmitting said message triggered by said received trigger message.

In an example, a switch comprised by said SMPS is arranged to operate in accordance with a duty cycle when it is enabled, and wherein said method further comprises the step of:

adapting, by said controller, said duty cycle when said wireless communication unit is to transmit said message.

In yet another example, the SMPS is arranged to operate, when it is enabled, according to a standby burst mode setting or a wireless communication setting, wherein said setting indicates parameters for said SMPS, wherein said method further comprises the step of:

setting, by said controller, said SMPS to said wireless communication setting mode when said wireless communication unit is to transmit said message.

In a third aspect, there is provided a computer program product comprising a computer readable medium having instructions stored thereon which, when loaded by a wireless communication node, cause said wireless communication node to implement a method in accordance with any of the claims 8 - 14.

In a fourth aspect, there is provided a lighting system comprising a plurality of wireless communication nodes in accordance with any of examples as provided above.

It is noted that the advantages and definitions as disclosed with respect to the embodiments of the first and second aspects of the invention also correspond to the third and fourth aspect of the present disclosure, being the computer readable medium and the lighting system, respectively.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 illustrates schematically a typical architecture of a mains supplied connected lighting system in accordance with the present disclosure.

Fig. 2 illustrates in a chart the burst mode operation of the SMPS in accordance with the present disclosure.

Fig. 3 illustrates in a chart the beacon interval of a RF networked system.

DETAIFED DESCRIPTION

Figure 1 illustrates a typical architecture of a wireless communication node 100. The wireless communication node 100 may be formed by a lighting unit like a Fight Emitting Diode, FED, lighting device. Another example of a wireless communication node 100 is a smoke detector, a IOT sensor device, a sprinkler device or anything alike.

The wireless communication node 100 is arranged to receive Alternating Current, AC, mains voltage as indicated with reference numeral 101. The AC mains voltage may be fdtered with by an Electromagnetic Interference, EMI, input fdter 102 before it is rectifier by a bridge rectifier 103. The EMI input filter 102 may, for example, be a common mode filter or a differential mode filter. The bridge rectifier 103 may, for example, be construed using a plurality of diodes.

A switching device 104, normally implemented as a Metal Oxide Semiconductor Field Effect Transistor, MOSFET, and a transformer 105 convert the DC voltage, provided by the rectifier 103, to an intermediate circuit voltage. The Switched Mode Power Supply, SMPS, may be formed by the switching device 104, the transformer 105, the output capacitor 106, as well as a feedback circuit comprised by the optocoupler 109.

The above disclosed SMPS is an isolated power supply as indicated with the vertical dash line penetrating the blocks with reference numeral 105 and 109. The present disclosure may also be operative using a non-isolated SMPS.

The voltage over the output capacitor 106 may supply both some functional units like a lighting unit 107 and the wireless communication unit 108. The lighting unit 107 may consist of a lamp driver for providing the current to a lighting source preferably a LED based light source.

The present disclosure is directed to the concept that, whenever the wireless communication unit 108 is to transmit a message, the SMPS is enabled.

Through optocoupler 109 the feedback voltage over the output capacitor 106 is fed back to the controller 110. As mentioned above, the SMPS is operative in accordance with a burst mode operation, meaning that the SMPS is active in an enabled mode and inactive in a disabled mode.

In an example, when the feedback voltage drops below a first threshold, the burst mode of the SMPS is enabled and the output capacitor 106 is charged. The burst mode of the SMPS is disabled when the feedback voltage exceeds the second threshold.

In the present disclosure, the controller 110 of the SMPS and wireless communication unit 108 are in communicative connection as indicated with the dashed line. The controller 110 may communicate to, i.e. control the, switching device 104 of the SMPS to enable burst mode before initiating transmission of a message, for example a beacon message, generated by the wireless communication unit 108. In this case, power is directly provided by the SMPS such that the size of the output capacitor may be reduced.

In an example, a coupling is established between an enable signal for the wireless communication unit 108 and the feedback signal. For example, a chip select signal is present on the serial interface between controller 110 and wireless communication unit 108. Via a capacitor and additionally some resistors and/or diodes for charge balancing of the capacitor and for blocking signals during other transitions, this transition/slope can directly be injected into the intermediate circuit feedback path.

Due to the bidirectional communication path between the wireless communication unit 108 and controller unit 110, the wireless communication unit 108 is able to trigger the controller 110 to provoke a burst start of the SMPS when the wireless communication unit 108 intends to start transmitting a message. On the other hand, controller 110 may inform the wireless communication unit 108 indicating that burst mode operation of the SMPS is being enabled such that wireless communication 108 may be activated for transmitting a message.

The wireless communication unit 108 may, at least, have an antenna for transmitting RF messages. Preferably, the wireless communication unit 108 comprises a transceiver for both sending and receiving RF messages. RF data communication protocols used for communication with connected nodes or network coordinates may be, for example, WiFi, Zigbee, LoRa, Z-wave, Internet of Things or other wireless data protocols.

The present disclosure is thus directed to the concept a wireless communication node 100 is arranged to operate in a wireless network, wherein said wireless communication node 100 is arranged for supplying power to an electrical load, for example the lighting unit 107, as well as arranged for wireless connectivity, as indicated with reference numeral 108. The wireless communication node comprising: a wireless communication unit 108 for providing wireless connectivity. The wireless communication unit 108 is, at least, arranged for wirelessly transmitting a message;

The latter is indicated with the dashed line between the controller 110 and the wireless communication unit 108. The controller may either be aware that the SMPS is in an enabled mode, or may actively control the SMPS to the enabled mode, before it controls the wireless communication node 108 for transmitting a message.

Figure 2 illustrates in a chart the burst mode operation of the SMPS in accordance with the present disclosure. When feedback voltage 201 of the intermediate circuit capacitor increases threshold 202 at time 203, burst mode operation of the SMPS is enabled and the intermediate capacitor at the output of the SMPS is charged. When feedback voltage 201 drops below threshold 202 at time 205, burst mode operation of the SMPS is disabled. This alternatively enabling and disabling results in a power efficient and stable output voltage of the SMPS. It is noted that figure 2 discloses a feedback voltage that is inversely proportional to the voltage provided by the SMPS. As such, it may seem that the SMPS is enabled when the voltage is above the voltage threshold as indicated with reference numeral 202, while in fact it means that the output voltage decreases to below a certain threshold.

Threshold 202 can be replaced with a hysteresis such that burst mode is enabled when the feedback voltage increases a first threshold and is disabled when the feedback voltage drops below a second threshold.

Figure 3 illustrates in a chart the beacon interval of a RF networked system.

Beacon interval 300 starts with transmitting beacon 301. The interval is split up in a superframe duration period 302 and inactive period 303. Superframe duration period 302 consists of contention access period 304 and contention free period 305. Beacon interval 300 is a configurable parameter in the access point expressed in Time Unit, TU. It is typically configured as 100 TU which corresponds to 102.4 ms. In view of the 20 ms time period of a 50 Hz main cycle, the TBTT can be synchronized with the 50 Hz or 60 Hz main cycle such that the SMPS bursts occur in time periods where the SMPS operates at high efficiency. This will typically be somewhat away from the zero crossings of the main voltage.

While from point of view of a single lamp, this results in reduced power consumption, for the complete installation, the burst mode power intake of all loads will result in a relatively high, short term current consumption, including the conducted EMI. In order to improve the system behaviour, e.g. not to create a dip in the mains voltage cycle which might light to flicker, the system can be set to prepone or postpone the burst pulses of some lamps.

TBTT can also be set independent of the 50 Hz or 60 Hz mains cycle. SMPS bursts are synchronized with the TBTT. The overlap of SMPS bursts with the mains cycle will then vary. SMPSS bursts resulting in a low efficiency of the SMPS will be skipped and the RF communication unit be supplied from the buffer capacitor instead.

Other variations to the disclosed examples can be understood and effected by those skilled in the art in practicing the claimed disclosure, from a study of the drawings, the disclosure and the appended claims. In the claims, the word“comprising” does not exclude other elements or steps and the indefinite article“a” or“an” does not exclude a plurality. A single processor or other unit may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program may be stored/distributed on a suitable medium, such as optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the internet or other wired or wireless

telecommunication systems. Any reference signs in the claims should not construed as limiting scope thereof. Similar reference signs denote similar or equivalent functionality.

The present disclosure is not limited to the examples as disclosed above, and can be modified and enhanced by those skilled in the art beyond the scope of the present disclosure as disclosed in the appended claims without having to apply inventive skills and for use in any data communication, data exchange and data processing environment.

Claims

CLAIMS:

1. A wireless communication node (100) arranged to operate in a wireless network, wherein said wireless communication node (100) is arranged for supplying power to a lighting unit (107) as well as arranged for wireless connectivity, said wireless

communication node (100) comprising:

a wireless communication unit (108) for providing wireless connectivity; a switched mode power supply, SMPS, arranged for supplying power to said electrical load (107) and to said wireless communication unit (108), wherein said SMPS operates in accordance with a burst mode operation, wherein said SMPS is alternatively enabled and disabled;

an output capacitor (106) coupled at the output of the switched mode power supply, the wireless communication unit (108) and the lighting unit (107);

a controller (110) arranged for ensuring that said SMPS is enabled when said wireless communication unit (108) is to transmit a message.

2. A wireless communication node according to claim 1, wherein said SMPS is arranged to alternatively be enabled and disabled in accordance with a feedback voltage from said supplied power, wherein said power supply is enabled when said feedback voltage is below a first threshold, and wherein said power supply is disabled when said feedback voltage is above a second threshold, and wherein said controller is arranged to actively increase any of the first and the second threshold triggered by said wireless communication unit is to transmit said message.

3. A wireless communication node in accordance with claim 2, wherein said controller is arranged to actively increase any of said first and second threshold triggered by said wireless communication unit stopping with transmitting said message.

4. A wireless communication node according to any of the previous claims, wherein said power supply is arranged for providing a trigger message to said controller thereby indicating that it is being enabled, and wherein said controller is arranged for activating said wireless communication unit for transmitting said message triggered by said received trigger message.

5. A wireless communication node according to any of previous claims, wherein a switch comprised by said SMPS is arranged to operate in accordance with a duty cycle when it is enabled, and wherein said controller is arranged to adapt said duty cycle when said wireless communication unit is to transmit said message.

6. A wireless communication node according to any of previous claims, wherein said SMPS is arranged to operate, when it is enabled, according to a standby burst mode setting or a wireless communication setting, wherein said setting indicates parameters for said SMPS, wherein said controller is arranged to set said SMPS to said wireless communication setting mode when said wireless communication unit is to transmit said message.

7. A method of operating a wireless communication node in accordance with any of the previous claims, wherein said method comprises the steps of:

8. A method in accordance with claim 7, wherein said wireless communication node further comprises a lighting unit for providing light, and wherein said step of supplying power comprises:

supplying power to said lighting unit.

9. A method in accordance with any of the claims 7 - 8, wherein said SMPS is arranged to alternatively be enabled and disabled in accordance with a feedback voltage from said supplied power, wherein said step of ensuring comprises:

enabling, by said controller, said SMPS when said feedback voltage is below a first threshold, and disabling, by said controller, said SMPS, when said feedback voltage is above a second threshold, and actively increase, by said controller, any of the first and the second threshold triggered by said wireless communication unit is to transmit said message.

10. A method in accordance with claim 9, wherein said method further comprises the step of:

actively increase, by said controller, an of said first and second threshold triggered by said wireless communication unit stopping with transmitting said message.

11. A method in accordance with any of the claims 7 - 10, wherein said method further comprises the step of:

providing, by said SMPS, a trigger message to said controller thereby indicating that it is being enabled, and wherein said step of ensuring comprises:

12. A method in accordance with any of the claims 7 - 11, wherein a switch comprised by said SMPS is arranged to operate in accordance with a duty cycle when it is enabled, and wherein said method further comprises the step of:

13. A computer program product comprising a computer readable medium having instructions stored thereon which, when loaded by a wireless communication node, cause said wireless communication node to implement a method in accordance with any of the claims 7 - 13.