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Title:
VOLTAGE REGULATOR
Document Type and Number:
WIPO Patent Application WO/2015/025133
Kind Code:
A1
Abstract:
Apparatus for regulating high power voltage supplies, comprising a voltage input, voltage regulating means arranged to receive the AC input voltage and output a regulated output voltage under control of a control means connected to the voltage regulating means, wherein the apparatus is provided with pulse width modulation means and temperature sensing means in communication with the control means and the voltage regulation means, and wherein control means is adapted to control the regulated output voltage by altering the pulse width modulation in dependence on the sensed temperature.

Inventors:
TYTLER, Duncan, George, Fraser (347 Kelston Road, BathBath and North East Somerset, BA1 9AD, GB)
Application Number:
GB2014/052494
Publication Date:
February 26, 2015
Filing Date:
August 14, 2014
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
UTILITYWISE PLC (30-31 Long Row, South Shields, Tyne and Wear NE33 1JA, GB)
International Classes:
H02M1/42; H02M5/12
Domestic Patent References:
WO2007017618A1
WO2013051133A1
Foreign References:
US20060083032A1
US6747884B2
GB2464287A
Attorney, Agent or Firm:
MURGITROYD & COMPANY (Scotland House, 165-169 Scotland StreetGlasgow, Strathclyde G5 8PL, GB)
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Claims:
CLAIMS

1. Apparatus for regulating voltage comprising:

an AC voltage input,

voltage regulating means arranged to receive the AC input voltage and output a regulated output voltage under control of a control means connected to the voltage regulating means,

wherein the apparatus is provided with pulse width modulation means and temperature sensing means in communication with the control means and the voltage regulation means, and wherein the control means is adapted to control the regulated output voltage by altering the pulse width modulation in dependence on the sensed temperature.

2. Apparatus according to claim 1 wherein the communication between the control means, the pulse width modulation means and the temperature sensing means is arranged as a feedback loop.

3. Apparatus according to claim 2 wherein the altering of the pulse width modulation via the feedback loop comprises increasing the mark space ratio of the modulation as the sensed temperature increases.

4. Apparatus according to claim 2 or claim 3, wherein the temperature sensing means is adapted to sense the temperature of at least one transforming output means provided to output the regulated output voltage.

5. Apparatus according to claim 4, wherein the transforming output means comprises three coils.

6. Apparatus according to claim 5, wherein the control means further comprises switching means to switch the pulse width modulated signal to the transforming output means.

7. Apparatus according to claim 6, wherein the switching means comprises at least one IGBT.

8. Apparatus according to any preceding claim, wherein the transforming output means are mounted on a heatsink.

9. Apparatus according to claim 1, wherein the AC input voltage supply is multi-phase. 10. Apparatus according to claim 9, wherein the altering of the pulse width modulation in dependence on the sensed temperature is provided synchronously across all phases by the control means.

11. Apparatus according to any preceding claim wherein the control means is adapted to provide control between a first level and a further level in dependence on the temperature sensed by sensing means reaching or exceeding a predetermined threshold.

12. Apparatus according to claim 11, wherein the predetermined threshold corresponds to the maximum operating voltage of the switching means.

13. A method of regulating voltage, comprising receiving an AC input voltage, applying a pulse width modulated signal to the AC input voltage to provide an output voltage, and altering the output voltage by altering the applied pulse width modulation in dependence on at least one sensed temperature.

14. A method according to claim 13, wherein the step of altering the output voltage further comprises altering the output voltage between a first level and a further level when the at least one sensed temperature exceeds a predetermined threshold.

15. A method according to claim 13 or claim 14, wherein the predetermined threshold is in the range 65 to 200 degrees centigrade.

16. A method according to any one of claims 13 to 15, wherein the predetermined threshold is in the range 100 to 200 degrees centigrade.

17. A method according to any one of claims 13 to 16, wherein the step of altering the output voltage is applied in both, "buck" and "boost" mode. 18. Apparatus as substantially described herein with reference to the accompanying description and figures.

Description:
VOLTAGE REGULATOR

TECHNICAL FIELD This invention relates to high voltage regulation equipment and apparatus and in particular to apparatus for controlling such equipment. The invention has particular, but not exclusive application in the field of consumer or commercial high power delivery and optimisation with respect to real-time energy demands supplied by multi-phase high power mains supply.

BACKGROUND

The regulation in voltage of a supplied mains voltage is known generally to provide certain benefits, such as a reduction in energy consumed by a load powered by such a regulated supply. Of course, the reduction in energy consumed may also provide a reduction in carbon dioxide emissions, and have other advantages such as reducing the ultimate bill or cost of the energy utilised by the user, and perhaps improving the longevity of appliances attached to such regulated power supplies. Apparatus for regulating or optimising such voltage supplies is disclosed in WO 2012/104651, which regulates voltage via energy measurement means which enables measurement of energy consumption differences across a site in both the unregulated and regulated voltage to enable users to know whether the voltage regulation device is leading to any energy saving.

A problem exists with such voltage regulators, in that the characteristics of the components of such depend on temperature. For example, components running at too high a temperature may present a safety risk and may suffer a reduced lifetime. It is a desire of the present invention to improve upon the above. SUMMARY OF INVENTION

In a first aspect there is a provided apparatus for regulating voltage comprising a voltage input, voltage regulating means arranged to receive the AC input voltage and output a regulated output voltage under control of a control means connected to the voltage regulating means, wherein the apparatus is provided with pulse width modulation means and temperature sensing means in communication with the control means and the voltage regulation means, and wherein the control means is adapted to control the regulated output voltage by altering the pulse width modulation in dependence on the sensed temperature.

Owing to the invention, it is possible to control delivery of high voltage supplies to for example a large industrial installation or a block of apartments in dependence on real time demand.

Advantageously, the use of pulse width modulation in dependence on the sensed temperature enables monitoring and control of the delivered output voltage to optimise power usage. In an embodiment the communication is a feedback loop which advantageously provides real-time monitoring and control.

In another embodiment, the ratio of the output voltage to the AC input voltage is proportional to the mark to space ratio of the pulse width modulation.

In yet another embodiment, the altering of the pulse width modulation via the feedback loop comprises altering the mark space ratio of the modulation as the sensed temperature increases. Preferably, the apparatus is provided with at least one output transforming means, for example as three coils, and the temperature sensing means is adapted to sense the temperature of the transforming output means to output the regulated output voltage.

In another embodiment, the control means further comprises switching means in the form of, for example, high voltage Insulated Gate Bipolar Transistors to switch the pulse width modulated signal to the transforming output means.

Advantageously, the switching means may be mounted on a heatsink, and the heatsink temperature may also be monitored by the temperature sensing means.

In another embodiment the control means and pulse width modulation means are adapted to provide control between a first level and a further level in dependence on the sensed temperature reaching or exceeding a predetermined threshold. In yet another embodiment, the AC input voltage is provided by three phase mains power supply lines.

In another aspect there is provided a method of regulating voltage, comprising receiving an AC input voltage, applying a pulse width modulated signal to the AC input voltage to provide an output voltage, and altering the output voltage by altering the applied pulse width modulation in dependence on at least one sensed temperature.

Further optional features will be apparent from the following description and accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example only with reference to the accompanying drawings, in which: Figure 1 depicts a block diagram of apparatus according to an embodiment of the invention;

Figure 2 illustrates a feedback loop arrangement incorporating pulse width monitoring means according to an embodiment of the invention;

Figure 3 illustrate a pulse width modulated waveform according to the embodiment of Figure 1;

Figure 4 is a diagram depicting the application of pulse width modulation to an AC input voltage and the accompanying output voltage;

Figure 5 is an example of a smoothed and filtered, pulse width modulated output waveform; Figure 6 illustrates the application of pulse width modulation in dependence on sensed temperature according to an embodiment of the invention;

Figure 7 is a block circuit diagram of an embodiment of the invention; DETAILED DESCRIPTION OF THE EMBODIMENTS

Figure 1 shows an embodiment in the form of a block diagram of voltage regulation apparatus 100. The figure shows an input mains supply voltage Vj n 110 (Inp). In this embodiment the input supply 110 is a three phase alternating current supply, although in other embodiments the input supply may be single or dual phase as recognised by those skilled in the art.

The mains input 110 is fed to transformers 120 which reduce ("buck") or increase ("boost") the output voltage V ou t 130 (0). To achieve the required "buck" or "boost", a certain percentage of voltage is added or subtracted. The maximum percentage variation depends, as those skilled in the art will recognise, on the primary to secondary winding ratio of the transformers 120. In this embodiment additional current transformers (CT) 140 are arranged on the output to accurately monitor the current output.

The secondary winding of the transformers 120 are connected to a control board 150 in order to regulate and control the output 130.

The control board 150 may be mounted on a heatsink 155 as shown in the Figure.

The control board 150 comprises power electronics circuitry 160 (PE) which provides general signal switching control, analogue to digital conversion, smoothing, and local power supply for example for low voltage microprocessors and the like, as will be discussed further below.

The control board 150 also has control means 170 in the form of a processor 170 (P) connected to switching means 180 and temperature sensing means 190 (T.Mon). The temperature sensing means 190 may be a temperature sensing module 190 comprising thermocouples (for example standard "K-type") and associated integrated circuits and circuitry. These are arranged to measure the temperature of each transformer 120 as a function of load and time (T C (L1, t), T C (L2, t), T C (L3, t)) through bus 195 as shown in the figure. The temperature of the control board itself Th(t) may also be monitored by temperature sensing means 190.

In this embodiment, the switching means 180 comprise high voltage Insulated Gate Bipolar Transistors (IGBTs). Suitable components 180 identified by the Applicant include STMicroelectronics STGW38IH130D - IGBT 1300V 63A 250W T0247. Those skilled in the art will recognise that such a listing means that the maximum voltage the device can withstand between the collector and emitter is 1300V, the maximum collector current is 63A, and T0247 is the packaging type. Alternatively, other options may be utilised such as, by way of example, switching modules incorporating multiple IGBTs, such as that of the semiconductor manufacture Infineon with part number FF150R12KS4. The processor 170 causes the switching means 180 to modulate the output of the transformers 120 via a pulse width modulation (PWM(MSP, t)) scheme having variable Mark (M) to Space (S) ratios, which ratio may be dependent on the measured temperatures 190. This will now be elaborated upon with reference to the remaining Figures.

Preferably, high power components such as the IGBTs 180 are thermally connected to the heatsink 155 to enable efficient and safe operation. Figure 2 illustrates in more detail a feedback loop arrangement of Figure 1 incorporating pulse width modulation means 200 connected to processor 170 and transformers 120. The processor 170 ultimately controls the output voltage 130; 220 via transformers 120 and switching circuitry 180. In an embodiment, the temperatures measured and monitored by temperature sensing module 190 of the transformers 120 T(C) and optionally the heatsink 160 and or the control board 150 are input to the processor 170 via 210. The processor, in dependence on these monitored temperatures, controls pulse width modulation circuitry 200 to alter the output voltage 130. Those skilled in the art will appreciate that the pulse width modulation means may be embodied as software or firmware running on the processor in connection with power and smoothing circuitry 160 to output the desired pulse width modulated waveform.

Figure 3 shows a sinusoidal alternating current input waveform 300 having a voltage amplitude 310 of V A . The waveform 300 may be approximated by a digitised square wave having a certain mark (M) to space (S) ratio as shown in the figure. Altering the M:S ratio will alter the actual output voltage as more clearly illustrated in Figure 4. Also, the pulse width modulation is applied directly to a proportion of the incoming signal, and then added or subtracted from the output.

Figure 4 shows a mains input 400 having a voltage amplitude 410 of Vj n . The input signal 400 is then pulse width modulated 420 by processor 170 and pulse width modulation means 200 to provide a modulated signal 430 with voltage amplitude VA depending on the mark (M) to space (S) ratio chosen. In this example, VA = Vj n , although this will not always be the case and is illustrated as such for simplicity and to aid understanding.

When this modulated signal 430 is filtered 440 an output waveform 450 with voltage amplitude 460 of V ou t results. In general, the ratio of V ou t/Vi n is proportional to the M/S ratio of the pulse width modulation. An example of this is illustrated in Figure 5, which shows that a pulse width modulation 500 of 50% (corresponding to a mark to space ratio of 1 : 2) produces an output signal 510 of 50% amplitude of the input.

Figure 6 illustrates pictorially the operation of an apparatus embodiment such as that depicted in Figures 1 and 2. Input stage 110 receives the mains input supply 600 with amplitude Vj n . The load on the transformers 120 is monitored by Processor 170 connected to switching means 180 and temperature sensing means 190 (T.Mon). This signal 600 is modulated by the pulse width modulation means 200 under control of the processor 170 to produce signal 610 with amplitude VA 620. This signal 610 is then filtered and smoothed 630 by the power electronics circuitry 160 to produce an output signal 640 with amplitude V ou t.

The processor 170 monitors load and temperature information 650 from the transformers 120 on each live phase and optionally from the heatsink 160 on which the control board 150 is mounted. As shown at box 660, if the sensed temperature increases towards or exceeds a predetermined threshold T max then the mark to space ratio of the pulse width modulated signal is increased. This results in new output waveform 670 which after smoothing 680 produces new regulated and optimised output voltage signal 690.

In yet another embodiment, the predefined temperature threshold T max may be set at the maximum operating temperature of the components utilised in, for example, the control or switching means. For example, IGBTs are often specified to operate up to 200°C, or more preferably up to about 170°C.

Hence, power consumption may advantageously be dynamically controlled within acceptable tolerance levels by using a pulse width modulation scheme with temperature monitoring.

In an embodiment, the apparatus may be configured for different operating modes. For example, a "normal" operation mode may comprise the following parameters: V in =250Vac, Vout =230Vac, Mark to Space ratio= 0.6

Tc(Ll, t) =70°C and T h (0.6, t) =90°C where T c is the temperature of the transformer (s) 120 and Th is the temperature of the heatsink.

If the temperatures monitored by the temperature monitoring means 190 increase then a "high" temperature mode may be employed by control 170;200 means. For example, if the transformer coils and/or heat sink exceed the preset values of 70°C and 90°C given above, i.e. T C (L1, t) =100°C and T h (0.6, t) =120°C then the processor 170 and switching means 180 alter the pulse width modulation 200 until the measured temperatures 190 drop back to within the first and further levels of the predefined "normal" mode, i.e. the following parameters may be set:

Vin Vout =247Vac, Mark to Space ratio= 0.9

Tc(Ll, t) =80°C and T h (0.9, t) =100°C.

In yet another embodiment, the predefined temperature threshold Tmax may be set at the maximum operating temperature of the components utilised in, for example, the control or switching means. For example, IGBTs are often specified to operate up to 200C, or more preferably up to about 170C. Optionally, a hysteresis loop technique may be employed to prevent the processor control means 170 altering continuously the pulse width modulation 200 when the sensed temperatures are close to the predetermined mode threshold values, thus avoiding induced harmonics and unwanted oscillation (and associated power loss) due to sharply switching input power levels and demands.

In yet another embodiment, Figure 7 illustrates a switching arrangement 700 for a multiphase input supply 720 (Lin). In the Figure, the arrangement for a single phase input supply is shown, comprising four groups 180a;180b;180c;180d of two IGBTs each respectively, i.e. 8 IGBTs. Such an arrangement would be replicated per phase of input. So, for a three phase input power supply, the arrangement in Figure 7 would be replicated another two times, therefore utilising 24 IGBTs in total. Those skilled in the art will recognise that the IGBTs may be provided individually as discretes, or provided in modules designed for connection in such high power delivery systems.

In Figure 7, the live or high voltage power supply 720 (Lin = Live in) is switched to transformer coils 120 via blocks 180a and 180b under control of the processor 170 (P) via control buses 730a and 730b. These blocks effectively add or "boost" the output voltage 130, via pulse width modulation in dependence on sensed temperature as discussed previously.

The neutral 710 (N) or floating earth power supply line is switched to transformer coils 120 via blocks 180c and 180d under control of the processor 170 (P) via control buses 730c and 730d respectively. These blocks effectively subtract or "buck" the output voltage 130, via pulse width modulation in dependence on sensed temperature as discussed previously.

In this embodiment, the altering of the pulse width modulation in dependence on the sensed temperature is preferably provided synchronously across all phases by the control means 170. Hence, in the above voltage regulation apparatus is described which includes an automated regulation of the mark to space ratio of a pulse width modulated output signal in dependence on at least one sensed temperature, thereby providing efficient, flexible and dynamic control dependent on the load and temperature therewith, whilst avoiding induced harmonics caused by sharply switching power levels.

Finally, it will be understood that the present invention has been described in its preferred embodiment and can be modified in many different ways without departing from the scope of the invention as defined by the appended claims. For example, by monitoring the incoming power (i.e. voltage and current) and the outgoing power (i.e. voltage and current), the pulse width modulation may be altered to "hunt" for the most efficient mode of operation, i.e. minimising the product of the voltage and the current on the output. In order to "hunt" for the most efficient mode of operation, real-time processing is required, as the loads drawing the power are non-linear and may have irregular patterns.