WO2011051719A2

WO2011051719A2 - Power supply apparatus

Info

Publication number: WO2011051719A2
Application number: PCT/GB2010/051811
Authority: WO
Inventors: Iain David Mosely
Original assignee: Converter Technology Limited
Priority date: 2009-10-28
Filing date: 2010-10-28
Publication date: 2011-05-05
Also published as: WO2011051719A3; GB0918897D0; GB2474864A

Abstract

A modular power supply system into which a user can plug various different power supply modules in order to provide a specific combination of output voltages for a given application. The power supply system has the capability for measurement of both the total input power drawn by the system and the output power delivered by each of the power conversion modules.

Description

Power Supply Apparatus

The present invention relates to apparatus for providing a power supply and in particular, but not limited to, apparatus for providing a reconfigurable power supply for the circuitry of an electronic product, and a power supply which allows the energy usage of an electronic product to be monitored.

It is well known that over the past few decades there has been an increasing demand for new generations of consumer electronic devices, office equipment, and other electrical and electronic goods having improved functionality, and offering a greater number integrated features, than their predecessors. As demand for more technologically complex products has increased, however, there has also been economic pressure to reduce product development times and the costs involved.

With each new generation of electrical and electronic products come additional demands, on the product's power supply, for conversion of the raw power from the product's main external power source to provide the voltages that the product requires to operate. Indeed, most modern electronic products need a multitude of different supply voltages to operate different parts of their system. A typical system, for example, may need +12V to operate a relay, +5V for interface logic and +3V3, +2V5, +1V8, +1V5 and +1V2 for core digital processors. However, frequently during new product development, power supply considerations are left late in the product development process often resulting in the use of inefficient Off the shelf solutions in which the various supply requirements are compromised.

The pressures on product design have been further compounded by the increasing political and public demands for products having greater energy efficiency which have arisen from increasing concern about the environmental impacts of inefficient energy usage. However, whilst the various teams or individuals responsible for developing the different parts of a complex product will inevitably endeavour to design for efficient energy usage, they often will not appreciate the impact that a relatively innocuous modification will have on overall energy efficiency. For example, even the addition of a line of code in a piece of control software, or changing the position or type of an electronic component, can have an undesirable impact on power consumption. Furthermore, once a prototype for such a complex product is completed, it is relatively difficult to isolate an individual electronic (or software) component that may be causing a disproportionate and possibly avoidable contribution to energy inefficiency.

The present invention aims to provide an improved power supply that mitigates at least one of the above issues.

In accordance with one aspect of the present invention there is provided a modular power supply system into which a user can plug various different power supply module boards in order to provide a specific combination of output voltages for a given application. In accordance with another aspect of the present invention there is provided a power supply system with the capability for measurement of both the total input power drawn by the system and the output power delivered by each of a plurality of power conversion modules.

In accordance with another aspect of the present invention there is provided Power supply apparatus for providing power to an electronic circuit the apparatus comprising: means for connecting said apparatus to an input power source that provides input power to the apparatus; means for converting the input power into a plurality of output voltages and for providing each said output voltage on a respective power rail; means for electrically connecting said electronic circuit to at least one said power rail; means for measuring the output power drawn from each said power rail by said electronic circuit; and means for outputting signals representative of the measurements made by the measuring means.

The measuring means may comprise a plurality of output power measurement modules each output power measurement module preferably being adapted for measuring at least one parameter representing the power drawn from a different respective power rail. The measuring means may be adapted to measure the input power drawn from the power source. Accordingly, the measuring means may comprise an input power measurement circuit adapted for measuring at least one parameter representing said input power. The input power measurement circuit may be adapted for outputting a signal representing the input power. The measuring means may alternatively or additionally comprise a microprocessor based circuit adapted to determine the measured output powers and/or the input power.

The microprocessor based circuit may be adapted to receive signals representing diagnostic information and to extract the diagnostic information from the signals.

The plurality of output voltages may comprise a main output voltage provided on a main power rail, and the converting means may comprise a primary converter for converting the input power into the main output voltage provided on the main power rail. The power supply apparatus may comprise a further converter for providing power to operate the measuring means and/or the converting means, the further converter preferably being separate to the primary converter.

The converting means may comprise at least one module interface adapted: preferably to receive a removably insertable converter module for providing at least a further one of the plurality of output voltages; and preferably to provide said further output voltage on a further power rail.

The power supply apparatus may comprise a system display. Accordingly, the outputting means may adapted to output the measurements for display to a user via the system display. The power supply apparatus may comprise means for receiving user inputs wherein the outputting means is preferably adapted to output the signals representative of the measurements based on said user inputs.

The input power measurement circuit and/or each output power measurement modules may be adapted for measuring at least one of power, voltage and current.

The microprocessor based circuit may determine said measured output powers and/or input power from inputs received from the output power measurement modules and/or the input power measurement circuit respectively.

The microprocessor based circuit may comprise means (e.g. a data connector) for interconnection with a remote computer system. The microprocessor based circuit may be adapted to determine the measured output powers and/or input power from measurements of voltage and/or current.

The signals representing diagnostic information may include: signals representing what the power conversion modules function is; signals representing information such as operating temperatures and/or fault conditions; signals representing information identifying the presence of the module in the power supply apparatus; signals representing information indicative of the module specification; and/or signals representing information indicative of the modules performance specification. The measuring means and/or the converting means may be powered by the primary converter. The further converter may convert the input power of an input power supply into a voltage for providing the power to operate the measuring means and/or the converting means. The input power may be an AC voltage/current, for example, a mains power supply or an AC current source or may be a DC voltage/current.

The outputting means may be part of the microprocessor based circuit.

In accordance with another aspect of the present invention there is provided power supply apparatus for providing power to an electronic circuit, the apparatus comprising: means for connecting said apparatus to an input power supply that provides input power to the apparatus; and means for converting the input power into a main output voltage and for providing said output voltage on a main power rail, wherein said converting means comprises at least one module interface adapted: to receive a removably insertable converter module for providing at least one further output voltage; to provide module input power to the converter module, when inserted in the interface, for conversion by the converter module into said further output voltage; and to provide said further output voltage on a further power rail; and means for electrically connecting said electronic circuit to at least one said power rail.

The power supply apparatus may comprise means for measuring the output power drawn from each said power rail by said electronic circuit; and may comprise means for outputting signals representative of the measurements made by the measuring means. The at least one module interface may be adapted to provide the main output voltage as the module input power.

The power supply apparatus may comprise circuitry adapted to output signals representing diagnostic information, wherein the power supply apparatus preferably comprises means for reading the diagnostic information, and wherein the at least one module interface is preferably adapted to interface with the converter module to provide said diagnostic to the reading means.

The at least one removable converter module may comprise circuitry adapted to receive a signal for enabling and/or disabling the converter module, wherein said power supply apparatus preferably comprises means for generating an enable and/or disable signal, and wherein the at least one module interface is preferably adapted to interface with the converter module to provide said enable and/or disable signal from said generating means to said converter module.

In accordance with another aspect of the present invention there is provided a power conversion module adapted for use in a power supply apparatus according to any of the power supply apparatus aspects, the module comprising: a power supply interface for releasable mechanical and electrical connection to a respective module interface of the power supply apparatus; means for receiving the module input power via said power supply interface; and a converter for converting the module input power into said further voltage.

The module input power may comprise the main output voltage or may comprise the input power and the converter may be adapted to convert the main output voltage or the input power respectively into said further output voltage.

The power conversion module may comprise circuitry adapted to output signals representing diagnostic information via the power supply interface. The power conversion module may comprise circuitry adapted to receive a signal for enabling and/or disabling the power conversion module via said power supply interface.

In accordance with another aspect of the present invention there is provided a method of determining the power usage of an electronic device comprising a plurality of electronic subsystems, the method comprising: electrically connecting at least one subsystem of the electronic device to a power rail of a power supply system according to any of the power supply apparatus aspects; measuring the power drawn from each power rail by the subsystem electrically connected to it.

The method of determining the power usage of an electronic device may comprise modifying the configuration of the at least one subsystem, preferably in dependence on the measurements made in said measuring step, to provide an optimised subsystem configuration.

The configuration modifying step may comprise modifying the configuration of the at least one subsystem to reduce its energy consumption, preferably in dependence on the measurements, to provide said optimised subsystem configuration.

In accordance with another aspect of the present invention there is provided a method of manufacturing an electronic device comprising at least one electronic subsystem, the method comprising: fabricating at least one electronic subsystem based on an optimised subsystem configuration provided in accordance with one of the above methods; and incorporating said subsystem in said electronic device.

In accordance with another aspect of the present invention there is provided an electronic device comprising at least one electronic subsystem the configuration of which is based on an optimised subsystem configuration provided in accordance with one of the above methods.

In accordance with another aspect of the present invention there is provided an electronic device comprising: a plurality of electronic subsystems; and power supply apparatus according to any of the power supply apparatus aspects; wherein each output power rail of said power supply apparatus is adapted to provide power to a respective electronic subsystem.

The invention will now be described by way of example only with reference to the attached figures in which:

Figure 1 shows a simplified three-dimensional view of a power conversion and monitoring system; Figure 2 is a simplified functional block schematic of the system of Figure 1 ; Figure 3 is a simplified functional block schematic of a power measurement circuit suitable for the system of Figures 1 and 2;

Figure 4 is a simplified functional block schematic of a power conversion module suitable for the system of Figures 1 and 2; Figure 5 is a simplified functional block schematic of another power measurement circuit suitable for the system of Figures 1 and 2;

Figure 6 is a simplified schematic of a microcontroller based system suitable for the system of Figures 1 and 2;

Figure 7 is a simplified flow-diagram illustrating operation of a microcontroller based system suitable for the system of Figures 1 and 2; and

Figure 8 is a simplified schematic of a host computer system suitable for controlling the system of Figures 1 and 2.

System Overview

Figures 1 and 2 show a power conversion and monitoring system generally at 10. Figure 1 shows a simplified three-dimensional view of the system 10 in which a number of components are omitted, for simplicity, to allow other beneficial aspects of the system 10 to be seen more clearly. Figure 2 is a functional block schematic of the system 10 shown in Figure 1 , illustrating how the key functional blocks of the system are connected. The power conversion and monitoring system 10 provides an easily adaptable multiple rail power supply for the circuitry of an electronic product (not shown). The power conversion and monitoring system 10 is further operable to provide input and output power monitoring for allowing the energy efficiency of different parts of the circuitry of the electronic product, when connected, to be assessed both together, and separately. The power system 10 is fabricated on a main circuit board 1 1 and includes a connector 13 via which input power can be provided to the system 10, in operation, from a raw power source 12. In this example, the connector 13 is a mains power connector for connection to an AC (alternating current) mains power supply (e.g. typically 85 to 265Vac at 50/60Hz). The power system 10 is provided with a primary power converter 16 which, in this example, is an AC to DC (direct current) converter for converting the AC voltage delivered by the mains power supply 12 into a 'main' DC output voltage 17. The main DC output voltage 17 is output, in operation, via one rail of an output connector 26 for supply to the circuitry of the electronic product.

The power conversion and monitoring system 10 is further provided with a plurality of secondary power conversion modules 22-1 to 22-n (referred to generally as 22), where n is the total number of power conversion modules connected for converting the main DC output voltage 17 into a plurality of further DC voltages as required by the circuitry. In operation, each further DC voltage is output, via a respective rail of the output connector, for supply to the circuitry of the electronic product.

As seen in Figure 1 , each secondary power conversion module is a 'pluggable' unit which can be plugged into respective sockets 21 in the power conversion and monitoring system 10 and removed in dependence on the requirements of the circuitry that the system 10 is to supply. For example, in the embodiment shown in Figure 1 there are four sockets 21 , each configured for receiving a respective secondary power conversion module 22-1 to 22-4. Thus, in addition to the main DC output voltage 17, the power system is capable of providing four further DC voltages. However, in the configuration shown in Figure 1 , only two secondary power conversion modules (22-3 and 22-4) are connected and, accordingly, the system is configured to provide only two of the possible four further DC voltages.

In operation to configure the power conversion and monitoring system 10 to the requirements of the circuitry it will supply, the secondary conversion modules 22 are selected to provide the required voltage rails from a pre-configured set of modules. Thus, the power conversion and monitoring system 10 is operable to provide a flexible multiple rail power supply that can be adapted to the requirements of the circuitry of the electronic product it is to supply with relative ease. For example, a multiple rail power supply can be fabricated, using the four socket version, which has a +12V (which may or may not be the main voltage) rail to operate a relay, a +5V rail for interface logic, and/or a +3V3 rail, a +1V8 rail, and/or a +1V2 rail for digital processing requirements. Further, any of the secondary conversion modules 22 may be inserted in any of the sockets 21 to provide even more flexibility in the possible arrangement of rails.

In this embodiment, the power supply system 10 is provided, on the input side of the primary power converter 16, with an input power measurement block 14 for measuring the average input power delivered by the raw power source 12. The system 10 is also provided with a plurality of output power measurement blocks 24-1 to 24-n+1 (referred to generally as 24), one on each output rail, for respectively measuring the DC voltage and current delivered via the main power rail, and by each connected secondary power conversion module 22. The input power and the DC voltage and DC current measurements are signalled to a microcontroller 18 of a measurement system 32 where the measurements are read, logged in memory, and analysed. The microcontroller 18 is programmed to calculate the output power from the measured DC voltages and DC currents, and to signal the measured currents and voltages, and the input and output powers, to an on-board system display 20 under the control of a plurality of user input controls 30.

The microcontroller 18 is also provided with a data connector 28 (e.g. a USB or Ethernet connection) to allow connection from the power supply board 10 to a host computer so that an application program on the host computer can be used to perform various standard or bespoke long-term data logging and control functions.

Thus, the power measurement and monitoring system 10 has the capability to measure both the total input power drawn by the system and the output power delivered by each of the plurality of pluggable power conversion modules. The system's on-board display 20 allows a user to monitor various different measurement parameters. The plurality of associated controls 30 allows the user to select and change the parameter being displayed and/or the power rail being monitored (e.g. input parameters, main output parameters, or parameters for one of the secondary power conversion modules 22). Accordingly, the power measurement and monitoring system 10 provides a flexible, stable, but generic power supply that can be adapted to the requirements of the product it is to supply at a very early stage in the product's design and development process without specialist power converter design expertise. The power monitoring features of the system allow each team or individual working on the development of a new product to understand the impact that their design has, on energy consumption, incrementally and in situ (i.e. without having to extract the information from post-prototype testing). For example, a programmer can assess the beneficial or negative impact of changing the coding of a particular software module immediately thereby avoiding spending time on a potentially energy inefficient dead-end.

Once a new product's design has been finalised, the required power supply comprising the required power conversion modules 22 can be fabricated, on a smaller scale, for example without the measurement and monitoring features and/or with the correct power conversion modules integrated into the main power conversion circuit. The finalised power supply can either be integrated with the rest of the circuit, if appropriate, or provided as a separate circuit card. The main components of the system illustrated in Figure 2 will now be described in more detail with reference to Figures 3 to 8.

Input Power Measurement

Figure 3 shows, by way of example, a functional block schematic of a circuit suitable for use in the input power measurement block 14 for the measurement of the energy drawn from the raw power source, and the output of a signal representing the measurement results to the microcontroller 18.

For the AC powered (i.e. mains voltage) system of this example, the power measurement block 14 comprises a power measurement chip 40 which monitors the instantaneous mains voltage via a potential divider circuit 41 , and current via an in-line shunt resistor 42 which, in this example, is in the neutral line.

In this AC powered example, the time varying instantaneous input power measurement is filtered using a low pass filter (not shown) to provide an output bitstream representing the average input power. Typically, the corner frequencies of this low pass filter would be aligned with the update rate of the system display 20 which, in this example, is about 1 Hz. The power measurement chip 40 provides the bitstream voltage waveform output 44, via an isolation barrier 46 (e.g. an opto-coupler), to the microcontroller 18. The average frequency of the output 44 over time is representative of the average input power. Accordingly, the microcontroller 18 can interpret the bitstream data 44 to determine the average power level that this represents.

The chip 40 may be, for example, in the form of a low cost energy metering IC such as an ADE7768 from Analog Devices (RTM).

Primary Power Converter

The primary power converter 16 uses the energy provided by the raw power source 12 to create a well regulated DC output voltage (i.e. the main DC output 17) from the less well regulated AC mains supply.

In this example, the primary power converter 16 comprises a rectifier and smoothing circuit for providing a smoothed intermediate DC voltage for conversion into the main DC output voltage 17. The primary power converter further comprises a DC to DC converter in the form of a pulse width modulation (PWM) controlled fly-back converter with galvanic isolation between its input and output. It will be appreciated, however, that the converter may use any of a wide range of standard converter circuits, in dependence on the application requirements, as described in more detail below. Module Converters

Figure 4 shows a simplified functional block schematic of a possible configuration for the secondary power conversion modules 22.

As seen in Figure 4, each secondary power conversion module 22 comprises a DC to DC power conversion circuit 50. When the module 22 is plugged into a respective socket 21 on the main system board 1 1 , the DC to DC power conversion circuit 50 will operate on the main DC output voltage 17, to step the voltage up or down in dependence on the requirements of the external circuit the system 10 is intended to supply.

A range of different modules are provided, each with a different DC to DC power conversion circuit 50, to allow the flexibility to configure a completely custom power supply with a wide range of output voltages (including, for example, +12V to operate a relay, +5V for interface logic and/or +3V3, +2V5, +1V8, +1V5 and/or +1V2). Accordingly, the respective conversion circuit 50 for each secondary power conversion module 22 varies in dependence on the conversion requirements. Typically, however, each module 22 will comprise a buck or synchronous buck converter for stepping the main DC voltage 17 down to a lower DC voltage level.

In this embodiment, each module 22 also comprises diagnostic circuitry 52 for signalling the microcontroller 18 what its function is, and diagnostic information such as operating temperatures and fault conditions. Specifically, the diagnostic circuitry 52 is operable to signal the microcontroller 18 with diagnostic information including: information indicating that the module 22 is present in its respective socket 21 ; information indicative of the module specification and its performance specification (e.g. output voltage and current capability); and information indicative of the operating temperature of the DC/DC converter controller integrated circuits.

Each secondary power conversion module 22 is also operable to receive control signals from the microcontroller 18 for initiating a remote shutdown, for sequencing the output rails to power up in a defined order if required (for example, where the circuitry being supplied requires that one rail is present before other rails), and or for enabling/disabling the module 22.

Typically secondary power conversion module 22 is rated with a power capability of under 20W.

Output power measurement Figure 5 shows, by way of example, a functional block schematic of a possible circuit configuration for use in each of the output power measurement blocks 24.

As shown, in this embodiment, each output power measurement block 24 includes a first voltage measurement circuit 60 for measuring the DC output voltage provided by the secondary power conversion module 22 (i.e. between the output voltage rail and the reference (ground) rail), or primary power converter 16, it serves. The measurement circuit 60 provides a signal 61 , which represents this voltage, to the microcontroller 18. Each output power measurement block 24 also includes a second voltage measurement circuit 62 for measuring the voltage dropped across a shunt resistor 64 provided in-line with the output power rail of the secondary power conversion module 22 or primary power converter 16. The second voltage measurement circuit 62 therefore measures a voltage that is indicative of the current through the shunt resistor 64 and hence the DC load current being drawn via that power rail by the circuitry it is supplying. The measurement circuit 62 provides a signal 63 which represents the measured voltage, and hence the current, to the microcontroller 18. The measured voltages from all the output power measurement blocks 24 are read by the microcontroller 18 and the measurements from each power measurement block 24 are multiplied together to give a measure of the output power provided by the secondary power conversion module 22 and the primary power converter 16. System Display

In this embodiment, the system display 20 comprises an LCD display which is driven, in operation, by the microcontroller based measurement system 32. The system display 20 provides key operating information to the user. The information which can be displayed via the system display 20 includes: the total measured input power; the measured DC voltage, load current and power, for each secondary converter module output rail and for the main DC output rail; and diagnostic information such as whether or not a converter module 22 is fitted in a specific slot. The peak and average output current for each secondary converter module output rail or for the main DC output rail can also be displayed. Manual Control Inputs (Interrupts)

In this embodiment, each user control 30 comprises a switch that the user can operate to perform a variety of different functions. These functions include changing the information displayed via the system display 20 between voltage, current and power, changing the information displayed between the main output rail and each of the secondary power conversion modules 22 (when present) and changing the information displayed to display input power. These functions also include resetting the data (e.g. peak current values) logged by the microcontroller 18.

Measurement System - Functional Structure

Figure 6 schematically illustrates the main components of the microcontroller based measurement system 32.

As shown, in addition to the microcontroller 18, the measurement system 32 includes interface circuitry 70: via which the microcontroller 18 receives the measurement signals from the input and output power measurement blocks 14, 24, the diagnostic information from the secondary power conversion modules 22, and inputs from the user controls 30. The microcontroller 18 also outputs parameters via the interface circuitry 70 for display via the system display 20.

The microcontroller 18 operates in accordance with software modules stored within memory 71. As shown, the software modules include, among other things, an operating system 69, an output power measurement module 72, an input power measurement module 73, a display module 74, a host computer interface module 75, a power converter interface module 76, a user interface module 77, and a data logging module 78.

In operation, the output power measurement module 72 reads and interprets the various DC voltages and DC currents via analogue to digital (A/D) converters in the interface circuitry 70, calculates the output power levels based on the multiplication of the measured DC output voltage and the DC output current and monitors peak values for these parameters. The input power measurement module 73, of this AC powered example, interprets the bit-stream signal from the input power measurement block 14 and monitors long term peak and average input power. The display module 74 controls the output of diagnostic information and system data such as voltage, current and power via the system display 20. The host computer interface module 75 allows the system 10 to be connected to and controlled via application software on a host computer connected via the data connecter 28 to allow a greater variety of monitoring and control functions to be used. The power converter interface module 76 is operable to recognise the presence and type of secondary power conversion modules 22 present in the system 10 and to provide control signals to the modules 22, for sequencing purposes, and to enable/disable any of the modules 22. The power converter interface module 76 is also operable to interpret diagnostic information received from the secondary power conversion modules 22. The user interface module 77 handles the inputs from the user controls 30 for facilitating user control of the contents of the system display 20. The data logging module 78 stores the measurement data in memory 71 and overwrites the stored data as new measurement data is received.

Measurement System - Operation

The flow chart of Figure 7 illustrates operation of the microcontroller based measurement system 32 in more detail. As seen in Figure 7, after power is applied (step S80) the microcontroller 18 enters an initialisation phase S82 during which it checks for the presence of the removable conversion modules 22, and enables any modules 22 which are present by outputting a respective enable signal. During initialisation the microcontroller 18 outputs preliminary information such as a product name, details of the secondary power conversion modules 22 present, etc. for display by the system display 20 (step S84).

After initialisation S82 the microcontroller 18 checks for the presence of a host computer on its data connector 28 (step S86). If a host computer having appropriate application software is present, then control is passed to the host computer (step S88) which then reads, analyses and logs measurement data in accordance with the functionality of the application software.

When a host computer is not present the microcontroller 18 retains control and enters a measurement phase (step S90) during which the microcontroller's measurement software modules 72, 73 read the voltage and current measurement data provided by the output power measurement blocks 24 and the input power measurement data provided by the input power measurement block 14. During the measurement phase S90, the power converter interface software module 76 reads the operating temperature data provided by the diagnostic circuitry 52 of the secondary power conversion modules 22 present in the system 10.

Once the measurement data is read, the output power measurement software module 72 calculates the output DC power levels from the DC voltages and DC currents provided by the output power measurement blocks 24 of the system 10 (step S92). The display module 74 then facilitates the output of measurements, in dependence on user requirements (steps S94 and S96).

The measurement, calculation, and display steps S92, S94, and S96 are repeated at an appropriate sampling frequency subject to interrupts provided via the user controls 30 at S98. Typically, for example, the system display will be updated about once every second. The interrupts allow the user to select (or cycle) parameters for display between, for example: the power, voltage and current parameters; the input and output power measurements; and/or the different output rails being used. The interrupts also allow the user to reset measurement parameters (such as the peak power, voltage or current) and to manually enable/disable the various secondary power conversion modules 22.

Computer Control

Figure 8 schematically illustrates the main components of a host computer 200 system including application software 100 for allowing the host to communicate directly with the modular power system 10.

While the system 10 is under the control of the host computer, the measurement data is acquired by the microcontroller based measurement system 32 and then stored in memory 71. The host computer reads and stores this data for longer term data logging. In effect, the host computer takes over the high level control of the power system 10 whilst low level parameter measurement continues to be performed by the microcontroller 18.

The application software 100 includes, among other things, an output power measurement module 102, an input power measurement module 104, a display module 106, a power system interface module 108, a power converter interface module 1 10, a user interface module 1 12, and a data logging module 1 14, each of which operates in a similar manner to the corresponding software module of the microcontroller based measurement system 32.

Accordingly, the output power measurement module 102 reads the various DC voltages and DC currents from the memory 71 of the microcontroller based measurement system 32, and calculates the output power levels based on the multiplication of the measured DC output voltage and the DC output current and monitors peak values for these parameters. The input power measurement module 104 reads the stored input power data from the memory 71 and monitors long term peak and average input power. The display module 106 controls the output of diagnostic information and system data such as voltage, current and power via the host computer's display 1 18. The power system interface module 108 facilitates interfacing with the power conversion and monitoring system 10 via the data connecter 28. The power converter interface module 1 10 is operable to recognise the presence and type of secondary power conversion modules 22 present in the system 10 and to provide control signals to the modules 22, for sequencing purposes, and to enable/disable any of the modules 22. The power converter interface module 110 is also operable to interpret diagnostic information from the secondary power conversion modules 22. The user interface module 1 12 in this case handles the inputs from the host computer's input devices such as a keyboard 120 and mouse 122. The data logging module 1 14 stores the measurement data in memory. The stored measurement data may be stored indefinitely in memory or on associated data storage media such as a hard drive thereby allowing more sophisticated data analysis functions, including detailed comparison with historic data, to be performed and graphical representations to be produced. Thus, the host computer 200 will directly control the operation of the various functions of the power measurement and conversion system 10 and will be able to read back operational data. The host computer application software 100 is able to provide a long-term data logging function which allows a user to monitor all the various power levels in the converter over an extended period of time. Thus, the user is advantageously provided with a simple way to understand and quantify the power requirements of the product being developed or parts of it and to compare those requirements with those of earlier versions of the product or part.

Modifications and Alternatives

It will be appreciated that although the raw power source 12 is described as being a mains AC power supply it could be any suitable power supply including a DC supply. For example, it may comprise: a telecoms DC input (e.g. typically 36 to 75Vdc); an automotive DC Input (Typically 12/24 or 48Vdc); an input from a renewable energy source (e.g. a solar panel, wind turbine, etc.); a battery or bank of batteries; a fuel cell; solar panel; or the like. In general, however, the raw power source is poorly regulated and either an AC or DC voltage. In the case of AC voltages, these may be single phase or three phase. In the case of a solar panel the input power may take the form of a DC current source. It will be appreciated that different measurement and conversion circuitry may be used depending on what type of raw energy power source is used. Where the input supply is a DC supply, for example, the key functional blocks of the power conversion and monitoring system 10 will be adapted accordingly. Specifically, the input power measurement block 14 and the primary power converter 16 will be modified to respectively measure and convert a DC input voltage. The power measurement block 14 may, for example, comprise a DC measurement circuit similar to that shown in Figure 5 for the secondary power conversion modules 22. Accordingly, the microcontroller 18 may calculate the input power by multiplication of the input DC voltage and input DC current measured by the DC to DC measurement circuit rather then extracting it from a bit-stream signal as in the case of AC powered systems.

The power topology used as the basis for the primary power converter 16 may be varied in dependence on the system application and performance requirements (e.g. efficiency, cost, size, and isolation requirements). Typically, for example the primary power converter would use one of the following power topologies or a variant of it: buck converter; boost converter; flyback converter; sepic converter; buck-boost converter; forward converter; push-pull converter; half bridge converter; full bridge converter; LLC converter. Furthermore, whilst a PWM control scheme has been described, other control schemes may be used. For example, a pulse frequency modulation (PFM) control scheme. It will also be appreciated that feed-forward techniques may be used.

Accordingly, the configuration of the power conversion and measurement system is very flexible, allowing a range of designs to be provided, each optimised for a different raw power source. It will further be appreciated that the power used to drive input power measurement block 14, the microcontroller 18, the system display 20 and/or the output power measurement blocks 24 may advantageously be provided by a separate converter in order to minimise their impact on the input and output power measurements thereby maximising its accuracy. Nevertheless, in a lower cost and more compact version of the system, the power used to drive input power measurement block 14, the microcontroller 18, the system display 20 and/or the output power measurement blocks 24 may be provided from the output of the primary power converter 16. In the lower cost version of the system a correction factor may be applied to the calculated input power to take account of the load associated with driving this additional circuitry.

Furthermore, the modular power system 10 could incorporate any number of modules 22, limited only by available power and board area considerations. Whilst the conversion modules 22 have been described as pre-configured, the modular configuration allows bespoke modules to be made for specific application requirements at relatively low cost.

Whilst the data connecter 28 has been described with reference to specific examples, it will be appreciated that any suitable wired or wireless interface may be used. Furthermore, a plurality of similar systems may be interconnected with a computer system to allow the energy demands of different circuits (for example different parts of a complex product) to be assessed and logged substantially simultaneously. This allows the potential energy demands of a product to be monitored during development and potential issues highlighted when corrective action is still possible (or less costly and time consuming).

In the above description, microcontroller 18 is described, for ease of understanding, as operating under the control of various discrete software modules. Whilst these software modules may be provided in this way for certain applications, in other applications these modules may be built into the overall operating system or code and so these modules may not be discernible as discrete entities. Further, the functionality performed by part or all of this software may be performed using one or more dedicated hardware circuits. However, the use of software modules is preferred as it facilitates the updating of microcontroller based system 32 in order to update its functionality. In another embodiment the microcontroller 18 may be connected directly to an output (or input) voltage rail via a potentiometer such that it is the microcontroller 18 can measures the DC voltage and current directly. It will be appreciated that the host computer system 200 may read the measurement data directly itself rather than the microcontroller 18 reading and storing the measurement data for subsequent, or real time, download and analysis by the host computer. The rail sequencing may be implemented by enabling the secondary power conversion modules 22 in the required order using appropriately timed enable signals.

It will be appreciated that whilst the secondary power conversion modules 22 are described as being rated with a power capability of under 20W some or all of the modules 22 could have a higher power rating for example, up to 100W or possibly greater (typically 5W to 100W). This is especially the case for certain applications (for example, power supply units for telecommunication applications) which have higher power requirements for certain rails.

The DC current may be filtered using a low pass filter to allow average power levels to be captured by the microcontroller 18. A peak capture circuit may also be used in parallel with the low-pass filter so that peak currents can also be measured.

Claims

1. Power supply apparatus for providing power to an electronic circuit the apparatus comprising: means for connecting said apparatus to an input power source that provides input power to the apparatus; means for converting the input power into a plurality of output voltages and for providing each said output voltage on a respective power rail; means for electrically connecting said electronic circuit to at least one said power rail; means for measuring the output power drawn from each said power rail by said electronic circuit; and means for outputting signals representative of the measurements made by the measuring means.

2. Apparatus according to claim 1 wherein the measuring means comprises a plurality of output power measurement modules each output power measurement module being adapted for measuring at least one parameter representing the power drawn from a different respective power rail.

3. Apparatus according to claim 1 or 2 wherein the measuring means is adapted to measure the input power drawn from the power source.

4. Apparatus according to claim 3 wherein the measuring means comprises an input power measurement circuit adapted for measuring at least one parameter representing said input power.

5. Apparatus according to claim 3 or 4 wherein the input power measurement circuit is adapted for outputting a signal representing said input power.

6. Apparatus according to any preceding claim wherein the measuring means comprises a microprocessor based circuit adapted to determine said measured output powers and/or input power.

7. Apparatus according to claim 6 wherein the microprocessor based circuit is adapted to receive signals representing diagnostic information and to extract said diagnostic information from said signals.

8. Apparatus according to any preceding claim wherein the plurality of output voltages comprise a main output voltage provided on a main power rail, and wherein the converting means comprises a primary converter for converting the input power into the main output voltage provided on the main power rail.

9. Apparatus according to claim 8 further comprising a further converter for providing power to operate the measuring means and/or the converting means, the further converter being separate to the primary converter.

10. Apparatus according to claims 8 or 9 wherein the converting means comprises at least one module interface adapted: to receive a removably insertable converter module for providing at least a further one of the plurality of output voltages; and to provide said further output voltage on a further power rail.

1 1. Apparatus according to any preceding claim further comprising a system display, wherein said outputting means is adapted to output said measurements for display to a user via said system display.

12. Apparatus according to any preceding claim further comprising means for receiving user inputs wherein the outputting means is adapted to output the signals representative of the measurements based on said user inputs.

13. Power supply apparatus for providing power to an electronic circuit, the apparatus comprising: means for connecting said apparatus to an input power supply that provides input power to the apparatus; and means for converting the input power into a main output voltage and for providing said output voltage on a main power rail, wherein said converting means comprises at least one module interface adapted: to receive a removably insertable converter module for providing at least one further output voltage; to provide module input power to the converter module, when inserted in the interface, for conversion by the converter module into said further output voltage; and to provide said further output voltage on a further power rail; and means for electrically connecting said electronic circuit to at least one said power rail.

14. Apparatus according to claim 13 wherein the apparatus further comprises: means for measuring the output power drawn from each said power rail by said electronic circuit; and means for outputting signals representative of the measurements made by the measuring means.

15. Apparatus according to claim 13 or 14 wherein the at least one module interface is adapted to provide the main output voltage as said module input power.

16. Apparatus according to any of claims 13 to 15 further comprising circuitry adapted to output signals representing diagnostic information, wherein said power supply apparatus comprises means for reading the diagnostic information, and wherein the at least one module interface is adapted to interface with the converter module to provide said diagnostic to said reading means.

17. Apparatus according to any of claims 13 to 16 wherein the at least one removable converter module comprises circuitry adapted to receive a signal for enabling and/or disabling the converter module, wherein said power supply apparatus comprises means for generating an enable and/or disable signal, and wherein the at least one module interface is adapted to interface with the converter module to provide said enable and/or disable signal from said generating means to said converter module.

18. A power conversion module adapted for use in a power supply apparatus according to any of claims 13 to 17, the module comprising: a power supply interface for releasable mechanical and electrical connection to a respective module interface of the power supply apparatus; means for receiving the module input power via said power supply interface; and a converter for converting the module input power into said further voltage.

19. A power conversion module according to claim 18 wherein the module input power comprises the main output voltage and the converter is adapted to convert the main output voltage to said further output voltage.

20. A power conversion module according to claim 18 or 19 comprising circuitry adapted to output signals representing diagnostic information via said power supply interface.

21. A power conversion module according to claim 18, 19 or 20 comprising circuitry adapted to receive a signal for enabling and/or disabling the power conversion module via said power supply interface.

22. A method of determining the power usage of an electronic device comprising a plurality of electronic subsystems, the method comprising: electrically connecting at least one subsystem of the electronic device to a power rail of a power supply system according to any of claims 1 to 17; measuring the power drawn from each power rail by the subsystem electrically connected to it.

23. A method according to claim 22 further comprising modifying the configuration of said at least one subsystem, in dependence on the measurements made in said measuring step, to provide an optimised subsystem configuration.

24. A method according to claim 23 wherein said configuration modifying step comprises modifying the configuration of said at least one subsystem to reduce its energy consumption, in dependence on the measurements, to provide said optimised subsystem configuration.

25. A method of manufacturing an electronic device comprising at least one electronic subsystem, the method comprising: fabricating at least one electronic subsystem based on an optimised subsystem configuration provided in accordance with the method of claim 23 or 24; and incorporating said subsystem in said electronic device.

26. An electronic device comprising at least one electronic subsystem the configuration of which is based on an optimised subsystem configuration provided in accordance with the method of claim 23 or 24.

27. An electronic device comprising: a plurality of electronic subsystems; and power supply apparatus according to any of claims 1 to 17; wherein each output power rail of said power supply apparatus is adapted to provide power to a respective electronic subsystem.

28. A power supply apparatus, a removable module, a power monitoring method, a method of manufacture, and a host computer substantially as herein described with reference to, or as shown in, Figures 1 to 8.