Multimode DC converter, power supply and electronic equipment

Abstract

The present invention provides a multi-mode DC converter, a power supply and an electronic device, belonging to the technical field of power supply. The converter includes: a first switch unit, a second switch unit, a third switch unit, a first inductor, a second capacitor and a controller; the first end of the first switch unit is connected to the positive input end, and the second end is respectively connected to the first end of the second switch unit, the first end of the third switch unit and the first end of the first inductor; the second end of the second switch unit is connected to the first end of the first capacitor and the negative pole of the battery; the second end of the third switch unit is respectively connected to the first end of the second capacitor and the positive output end; the second end of the first inductor, the second end of the first capacitor and the second end of the second capacitor are all connected to the negative input end, the negative output end and the positive pole of the battery; the multi-mode DC converter can work in different working modes. The present invention provides a new DC converter topology with multiple working modes, a small number of components, and high reliability and stability.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply, and in particular to a multi-mode direct current converter, a power supply and an electronic device. Background Art

[0002] With the development of energy crisis and the increasing prominence of environmental problems, some equipment is usually equipped with energy recovery system to convert mechanical energy into electrical energy for storage. Energy recovery system usually includes: DC converter and battery.

[0003] When used in energy recovery systems, DC converters usually have multiple operating modes, including plug-in charging mode, battery discharge mode, and energy recovery mode. In plug-in charging mode, the power supply charges the battery through the DC converter; in battery discharge mode, the battery discharges through the DC converter to supply power to the load; in energy recovery mode, the load end charges the battery through the DC converter.

[0004] In the prior art, a two-stage charging system is usually used for a DC converter with a battery, which has a complex structure, many components and a large size. Summary of the invention

[0005] The embodiments of the present invention provide a multi-mode DC converter, a power supply and an electronic device to solve the problem that the DC converter with a battery in the prior art adopts a two-stage charging system, has a complex structure, many components and a large volume.

[0006] In a first aspect, an embodiment of the present invention provides a multi-mode DC converter, comprising: a first switch unit, a second switch unit, a third switch unit, a first inductor, a second capacitor and a controller;

[0007] The first end of the first switch unit is connected to the positive input end, and the second end of the first switch unit is respectively connected to the first end of the second switch unit, the first end of the third switch unit and the first end of the first inductor;

[0008] The second end of the second switch unit is connected to the first end of the first capacitor, and the second end of the second switch unit is also used to connect to the negative electrode of the battery;

[0009] The second end of the third switch unit is connected to the first end and the positive output end of the second capacitor respectively;

[0010] The second end of the first inductor, the second end of the first capacitor, and the second end of the second capacitor are all connected to the negative input terminal and the negative output terminal; the negative output terminal is also used to connect to the positive electrode of the battery;

[0011] The positive input terminal and the negative input terminal are used to connect to a DC power supply, and the positive output terminal and the negative output terminal are used to supply power to a load;

[0012] The controller is connected to the control end of the first switch unit, the control end of the second switch unit, and the control end of the third switch unit respectively, and is used to control the on and off of the first switch unit, the second switch unit, and the third switch unit so that the multi-mode DC converter works in different working modes.

[0013] Optionally, the first switch unit, the second switch unit and the third switch unit are all formed by switch tubes.

[0014] Optionally, the switch tube is a MOS tube.

[0015] Optionally, the second switch unit includes: a second switch tube, the second switch tube has a body diode, and the anode of the body diode of the second switch tube is connected to the second end of the second switch unit, and the cathode of the body diode of the second switch tube is connected to the first end of the second switch unit; controlling the on and off of the first switch unit, the second switch unit, and the third switch unit so that the multi-mode DC converter operates in different operating modes, including:

[0016] Controlling the second switch unit and the third switch unit to be disconnected, and controlling the first switch unit to be turned on according to a first preset duty cycle, so that the multi-mode DC converter operates in the first mode;

[0017] Wherein, in the first mode, the DC power supply charges the battery.

[0018] Optionally, controlling the first switch unit to be turned on according to a first preset duty cycle includes:

[0019] Acquire a current flowing through the first switch unit, and determine a modulation signal according to the current flowing through the first switch unit;

[0020] Obtaining the rated charging power of the battery, the actual charging voltage of the battery, and the actual charging current of the battery, and determining a carrier signal according to the rated charging power of the battery, the actual charging voltage of the battery, and the actual charging current of the battery;

[0021] A first PWM signal is generated based on the carrier signal and the modulation signal; the first PWM signal is used to drive the first switch unit to be turned on according to a first preset duty cycle.

[0022] Optionally, the carrier signal is determined according to the rated charging power of the battery, the actual charging voltage of the battery, and the actual charging current of the battery, including:

[0023] Determine the rated charging current of the battery according to the rated charging power of the battery and the actual charging voltage of the battery;

[0024] Subtract the actual charging current of the battery from the rated charging current of the battery to obtain the current offset;

[0025] The current offset is input into the PI controller to obtain a current control signal, and a carrier signal is generated according to the current control signal.

[0026] Optionally, the third switch unit includes: a third switch tube, the third switch tube has a body diode, and the anode of the body diode of the third switch tube is connected to the first end of the third switch unit, and the cathode of the body diode of the third switch tube is connected to the second end of the third switch unit; by controlling the on and off of the first switch unit, the second switch unit and the third switch unit, the multi-mode DC converter operates in different working modes, including:

[0027] Controlling the first switch unit and the third switch unit to be disconnected, and controlling the second switch unit to be turned on according to a second preset duty cycle, so that the multi-mode DC converter operates in the second mode;

[0028] In the second mode, the battery discharges to supply power to the load.

[0029] Optionally, the second switch unit includes: a second switch tube, the second switch tube has a body diode, and the anode of the body diode of the second switch tube is connected to the second end of the second switch unit, and the cathode of the body diode of the second switch tube is connected to the first end of the second switch unit; by controlling the on and off of the first switch unit, the second switch unit and the third switch unit, the multi-mode DC converter operates in different working modes, including:

[0030] Controlling the first switch unit and the second switch unit to be disconnected, and controlling the third switch unit to be turned on according to a third preset duty cycle, so that the multi-mode DC converter operates in a third mode;

[0031] In the third mode, the energy at the load end is used to charge the battery.

[0032] In a second aspect, an embodiment of the present invention provides a power supply, comprising a multi-mode DC converter as provided in the first aspect of the embodiment of the present invention.

[0033] In a third aspect, an embodiment of the present invention provides an electronic device, comprising a power supply as provided in the second aspect of the embodiment of the present invention.

[0034] The embodiment of the present invention provides a multi-mode DC converter, a power supply and an electronic device. The multi-mode DC converter includes: a first switch unit, a second switch unit, a third switch unit, a first inductor, a second capacitor and a controller; the first end of the first switch unit is connected to the positive input end, and the second end of the first switch unit is respectively connected to the first end of the second switch unit, the first end of the third switch unit and the first end of the first inductor; the second end of the second switch unit is connected to the first end of the first capacitor, and the second end of the second switch unit is also used to connect to the negative electrode of the battery; the second end of the third switch unit is respectively connected to the first end and the positive output end of the second capacitor; the second end of the first inductor, the second end of the first capacitor and the second end of the second capacitor are all connected to the negative input end and the negative output end; the negative output end is also used to connect to the positive electrode of the battery; the positive input end and the negative input end are used to connect to the DC power supply, and the positive output end and the negative output end are used to power the load; the controller is respectively connected to the control end of the first switch unit, the control end of the second switch unit and the control end of the third switch unit, and is used to control the on and off of the first switch unit, the second switch unit and the third switch unit to make the multi-mode DC converter work in different working modes. The embodiment of the present invention provides a new multi-mode DC converter topology, which can meet the requirements of three different working modes by only setting three switch units, one inductor and two capacitors. The circuit structure is simple, the number of components is small, the volume is small, the control method is simple, and the stability and reliability are high. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0036] Figure 1 is a structural schematic diagram of a multi-mode DC converter provided by an embodiment of the present invention;

[0037] Figure 2 yes Figure 1 An equivalent circuit diagram of the multi-mode DC converter shown in the first mode;

[0038] Figure 3 yes Figure 1 Another equivalent circuit diagram of the multi-mode DC converter shown in the first mode;

[0039] Figure 4 yes Figure 1 The control loop diagram of the multi-mode DC converter shown in the first mode;

[0040] Figure 5yes Figure 1 An equivalent circuit diagram of the multi-mode DC converter shown in the second mode;

[0041] Figure 6 yes Figure 1 Another equivalent circuit diagram of the multi-mode DC converter shown in the second mode;

[0042] Figure 7 yes Figure 1 An equivalent circuit diagram of the multi-mode DC converter shown in the third mode;

[0043] Figure 8 yes Figure 1 Another equivalent circuit diagram of the multi-mode DC converter shown in the third mode. DETAILED DESCRIPTION

[0044] In order to enable people in the technical field to better understand the present solution, the technical solution in the embodiment of the present solution will be clearly described below in conjunction with the drawings in the embodiment of the present solution. Obviously, the described embodiment is an embodiment of a part of the present solution, not all of the embodiments. Based on the embodiments in the present solution, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present solution.

[0045] The term "including" and any other variations in the specification and claims of this solution and the above drawings mean "including but not limited to", and is intended to cover non-exclusive inclusions and is not limited to the examples listed in the text. In addition, the terms "first" and "second" are used to distinguish different objects, not to describe a specific order.

[0046] For a DC converter with a battery, in battery discharge mode, the battery voltage needs to be boosted to power the load. When the battery voltage is greater than the DC bus voltage, the battery will be forced to reduce the voltage. In energy recovery mode, if the DC bus voltage is greater than or close to the battery voltage, a voltage reduction operation is required; if the DC bus voltage is less than the battery voltage, a voltage boost operation is required. Therefore, a DC converter that can switch between multiple modes is required.

[0047] In the prior art, a two-stage charging system is usually used to meet the needs of multi-mode operation, but the system has a complex structure, many components, high cost and large size.

[0048] Based on the above, Figure 1 A schematic diagram of the structure of a multi-mode DC converter provided by an embodiment of the present invention. Figure 1 , the multi-mode DC converter includes: a first switch unit 11, a second switch unit 12, a third switch unit 13, a first inductor L1, a second capacitor C2 and a controller;

[0049] The first end of the first switch unit 11 is connected to the positive input end, and the second end of the first switch unit 11 is respectively connected to the first end of the second switch unit 12, the first end of the third switch unit 13 and the first end of the first inductor L1;

[0050] The second end of the second switch unit 12 is connected to the first end of the first capacitor C1, and the second end of the second switch unit 12 is also used to be connected to the negative electrode of the battery BAT;

[0051] The second end of the third switch unit 13 is connected to the first end and the positive output end of the second capacitor C2 respectively;

[0052] The second end of the first inductor L1, the second end of the first capacitor C1, and the second end of the second capacitor C2 are all connected to the negative input terminal and the negative output terminal; the negative output terminal is also used to connect to the positive electrode of the battery BAT;

[0053] The positive input terminal and the negative input terminal are used to connect to the DC power supply Vin, and the positive output terminal and the negative output terminal are used to supply power to the load;

[0054] The controller is connected to the control end of the first switch unit 11, the control end of the second switch unit 12, and the control end of the third switch unit 13, respectively, and is used to control the on and off of the first switch unit 11, the second switch unit 12, and the third switch unit 13 so that the multi-mode DC converter works in different working modes.

[0055] The embodiment of the present invention provides a new topology of a multi-mode DC converter, which only requires three switch tubes, two capacitors and one inductor to be compatible with three different working modes, has a simple topology, a small number of components, low cost and a small size.

[0056] In a possible implementation manner, the first switch unit 11 , the second switch unit 12 , and the third switch unit 13 may all be formed by switch tubes ( Q1 , Q2 , and Q3 ).

[0057] In the embodiment of the present invention, each switch unit may be formed by a switch tube (Q1, Q2 and Q3), and the on-off of each switch unit is controlled by controlling the on-off of the switch tube.

[0058] In a possible implementation manner, the switch tube may be a MOS tube.

[0059] In one possible implementation, reference Figure 1The second switch unit 12 may include: a second switch tube Q2, the second switch tube Q2 has a body diode, and the anode of the body diode of the second switch tube Q2 is connected to the second end of the second switch unit 12, and the cathode of the body diode of the second switch tube Q2 is connected to the first end of the second switch unit 12; controlling the on and off of the first switch unit 11, the second switch unit 12 and the third switch unit 13 so that the multi-mode DC converter works in different working modes, including:

[0060] Control the second switch unit 12 and the third switch unit 13 to be turned off, and control the first switch unit 11 to be turned on according to a first preset duty cycle, so that the multi-mode DC converter operates in the first mode;

[0061] Wherein, in the first mode, the DC power source Vin charges the battery BAT.

[0062] refer to Figure 1 , control the second switch unit 12 and the third switch unit 13 to be disconnected, and control the first switch unit 11 to be turned on according to the first preset duty cycle.

[0063] Specifically, when the first switch unit 11 is turned on, Figure 2 The DC power source Vin charges the first inductor L1 through the first switch unit 11, and the first inductor L1 stores energy, and the current increases linearly; at the same time, the first capacitor C1 charges the battery BAT, and the voltage of the first capacitor C1 gradually increases. When the first switch unit 11 is disconnected, a Figure 3 In the current path shown, the energy stored in the first inductor L1 is used to charge the battery BAT. The first switch unit 11 operates according to a first preset duty cycle to step down the voltage of the DC power source Vin to charge the battery BAT.

[0064] The first preset duty cycle may be determined according to a voltage step-down ratio between the voltage of the DC power source Vin and the voltage of the battery BAT.

[0065] In a possible implementation, controlling the first switch unit 11 to be turned on according to the first preset duty cycle may include:

[0066] S101: Obtaining the current flowing through the first switch unit 11 i s1 , and according to the current flowing through the first switch unit 11 i s1 Determine the modulation signal v i ;

[0067] S102: Obtaining the rated charging power of the battery BAT P ba * , the actual charging voltage of the battery BATv ba And the actual charging current of the battery BAT i ba , and according to the rated charging power of the battery BAT P ba * , the actual charging voltage of the battery BAT v ba And the actual charging current of the battery BAT i ba Determine the carrier signal v c ;

[0068] S103: Based on carrier signal v c and modulation signal v i A first PWM signal PWM1 is generated; the first PWM signal PWM1 is used to drive the first switch unit 11 to be turned on according to a first preset duty cycle.

[0069] As charging proceeds, the voltage of the battery BAT is constantly changing, and the first preset duty cycle is also constantly changing. In the embodiment of the present invention, a loop is used to control the multi-mode DC converter to achieve step-down charging of the battery BAT. Figure 4 First, according to the current flowing through the first switch unit 11 i s1 Determine the modulation signal v i , and then determine the carrier signal according to the charging parameters of the battery BAT v c , carrier signal v c With modulation signal v i By comparison, a first PWM signal PWM1 is generated to drive the first switch unit 11 .

[0070] In a possible implementation, S101 may include:

[0071] 1. The current flowing through the first switch unit 11 i s1 Convert to voltage signal and integrate to get modulation signal v i .

[0072] refer to Figure 4 , inversion (-1) is used to eliminate the signal inversion caused by the operational amplifier. At the end of each switching cycle, the voltage signal is 0, and a new integration begins in the next cycle.

[0073] In a possible implementation, S102 may include:

[0074] 1. According to the rated charging power of battery BAT P ba * And the actual charging voltage of the battery BAT v ba , determine the rated charging current of battery BAT i ba * ;

[0075] 2. Set the rated charging current of battery BAT i ba * Subtract the actual charging current of the battery BAT i ba , get the current offset;

[0076] 3. Input the current offset into the PI controller to obtain the current control signal v cont , and according to the current control signal v cont Generate carrier signal v c .

[0077] In the embodiment of the present invention, the charging of the battery BAT is controlled by a current loop.

[0078] Specifically, refer to Figure 4 The current control signal is calculated by double integration to obtain a parabolic carrier signal, realizing the carrier signal v c The double integral is reset at the end of each cycle; for details, refer to Figure 4 , which can be realized by using a clock generator.

[0079] In one possible implementation, reference Figure 1 The third switch unit 13 may include: a third switch tube Q3, the third switch tube Q3 has a body diode, and the anode of the body diode of the third switch tube Q3 is connected to the first end of the third switch unit 13, and the cathode of the body diode of the third switch tube Q3 is connected to the second end of the third switch unit 13; by controlling the on and off of the first switch unit 11, the second switch unit 12 and the third switch unit 13, the multi-mode DC converter operates in different working modes, including:

[0080] Controlling the first switch unit 11 and the third switch unit 13 to be turned off, and controlling the second switch unit 12 to be turned on according to a second preset duty cycle, so that the multi-mode DC converter operates in the second mode;

[0081] In the second mode, the battery BAT is discharged to supply power to the load.

[0082] refer to Figure 1 , control the first switch unit 11 and the third switch unit 13 to be turned off, and control the second switch unit 12 to be turned on according to the second preset duty cycle.

[0083] Specifically, when the second switch unit 12 is turned on, Figure 5 In the current path shown, the battery BAT charges the first inductor L1 through the second switch unit 12, and the first inductor L1 stores energy. When the second switch unit 12 is disconnected, a Figure 6 In the current path shown, the first inductor L1 releases energy and supplies power to the load through the body diode of the third switch unit 13. The second switch tube Q2 operates according to the second preset duty cycle to boost the battery BAT and supply power to the load.

[0084] Similarly, a loop circuit can also be used to control the multi-mode DC converter. The specific loop circuit will not be described in detail here.

[0085] In one possible implementation, reference Figure 1 The second switch unit 12 includes: a second switch tube Q2, the second switch tube Q2 has a body diode, and the anode of the body diode of the second switch tube Q2 is connected to the second end of the second switch unit 12, and the cathode of the body diode of the second switch tube Q2 is connected to the first end of the second switch unit 12; by controlling the on and off of the first switch unit 11, the second switch unit 12 and the third switch unit 13, the multi-mode DC converter operates in different working modes, including:

[0086] Controlling the first switch unit 11 and the second switch unit 12 to be turned off, and controlling the third switch unit 13 to be turned on according to a third preset duty cycle, so that the multi-mode DC converter operates in the third mode;

[0087] In the third mode, the energy at the load end is used to charge the battery BAT.

[0088] refer to Figure 1 , control the first switch unit 11 and the second switch unit 12 to be turned off, and control the third switch unit 13 to be turned on according to a third preset duty cycle.

[0089] Specifically, when the third switch unit 13 is turned on, Figure 7 The current path shown in FIG. 1 is a current path in which the energy recovered from the load end charges the first inductor L1 through the third switch unit 13. When the third switch unit 13 is disconnected, a Figure 8In the current path shown, the energy stored in the first inductor L1 charges the battery BAT and the first capacitor C1 through the body diode of the second switch unit 12. The third switch unit 13 operates according to the third preset duty cycle to step down the voltage to charge the battery BAT.

[0090] The above converter is described below in conjunction with a specific embodiment. Figure 1 The multi-mode DC converter shown in the figure operates in three different operating modes. Experiments show that the peak efficiencies in the plug-in charging mode, battery discharging mode and energy recovery mode are 96.4%, 96.9% and 97.2% respectively. Compared with the converter in the prior art, it has not only a simple topology structure, a small number of components, but also higher efficiency, reliability and stability.

[0091] Corresponding to the above embodiments, an embodiment of the present invention provides a power supply, including any one of the multi-mode DC converters provided in the above embodiments of the invention, and having the advantages of the above multi-mode DC converter, which will not be described in detail here.

[0092] Corresponding to the above embodiments, an embodiment of the present invention provides an electronic device, including any one of the power supplies provided in the above embodiments, and having the advantages of the above power supplies, which will not be described in detail here.

[0093] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-mode DC converter, characterized in that: include: A first switch unit, a second switch unit, a third switch unit, a first inductor, a first capacitor, a second capacitor and a controller; The first end of the first switch unit is connected to the positive input end, and the second end of the first switch unit is respectively connected to the first end of the second switch unit, the first end of the third switch unit and the first end of the first inductor; the second end of the second switch unit is connected to the first end of the first capacitor, and the second end of the second switch unit is also used to connect to the negative electrode of the battery; the second end of the third switch unit is respectively connected to the first end and the positive output end of the second capacitor; the second end of the first inductor, the second end of the first capacitor and the second end of the second capacitor are all connected to the negative input end and the negative output end; the negative output end is also used to connect to the positive electrode of the battery; the positive input end and the negative input end are used to connect to a DC power supply, and the positive output end and the negative output end are used to supply power to a load; The controller is connected to the control end of the first switch unit, the control end of the second switch unit, and the control end of the third switch unit, respectively, and is used to control the on and off of the first switch unit, the second switch unit, and the third switch unit so that the multi-mode DC converter works in different working modes; The second switch unit includes: a second switch tube, the second switch tube has a body diode, and the anode of the body diode of the second switch tube is connected to the second end of the second switch unit, and the cathode of the body diode of the second switch tube is connected to the first end of the second switch unit; the control of the on and off of the first switch unit, the second switch unit and the third switch unit so that the multi-mode DC converter works in different working modes includes: Controlling the second switch unit and the third switch unit to be disconnected, and controlling the first switch unit to be turned on according to a first preset duty cycle, so that the multi-mode DC converter operates in a first mode; Wherein, in the first mode, the DC power supply charges the battery; The controlling the first switch unit to be turned on according to a first preset duty cycle includes: Acquire a current flowing through the first switch unit, and determine a modulation signal according to the current flowing through the first switch unit; Acquiring the rated charging power of the battery, the actual charging voltage of the battery, and the actual charging current of the battery, and determining a carrier signal according to the rated charging power of the battery, the actual charging voltage of the battery, and the actual charging current of the battery; A first PWM signal is generated based on the carrier signal and the modulation signal; the first PWM signal is used to drive the first switch unit to be turned on according to the first preset duty cycle.

2. The multi-mode DC converter according to claim 1, characterized in that: The first switch unit, the second switch unit and the third switch unit are all formed by switch tubes.

3. The multi-mode DC converter according to claim 2, characterized in that: The switch tube is a MOS tube.

4. The multi-mode DC converter according to claim 1, characterized in that: The determining of the carrier signal according to the rated charging power of the battery, the actual charging voltage of the battery and the actual charging current of the battery comprises: Determining a rated charging current of the battery according to the rated charging power of the battery and the actual charging voltage of the battery; Subtracting the actual charging current of the battery from the rated charging current of the battery to obtain a current offset; The current offset is input into a PI controller to obtain a current control signal, and the carrier signal is generated according to the current control signal.

5. The multi-mode DC converter according to any one of claims 1 to 3, characterized in that: The third switch unit includes: a third switch tube, the third switch tube has a body diode, and the anode of the body diode of the third switch tube is connected to the first end of the third switch unit, and the cathode of the body diode of the third switch tube is connected to the second end of the third switch unit; the multi-mode DC converter operates in different working modes by controlling the on and off of the first switch unit, the second switch unit and the third switch unit, including: Controlling the first switch unit and the third switch unit to be disconnected, and controlling the second switch unit to be turned on according to a second preset duty cycle, so that the multi-mode DC converter operates in a second mode; Wherein, in the second mode, the battery discharges to supply power to the load.

6. The multi-mode DC converter according to any one of claims 1 to 3, characterized in that: The second switch unit includes: a second switch tube, the second switch tube has a body diode, and the anode of the body diode of the second switch tube is connected to the second end of the second switch unit, and the cathode of the body diode of the second switch tube is connected to the first end of the second switch unit; the multi-mode DC converter operates in different working modes by controlling the on and off of the first switch unit, the second switch unit and the third switch unit, including: Controlling the first switch unit and the second switch unit to be turned off, and controlling the third switch unit to be turned on according to a third preset duty cycle, so that the multi-mode DC converter operates in a third mode; Wherein, in the third mode, the energy at one end of the load is used to charge the battery.

7. A power supply, characterized in that: It comprises a multi-mode DC converter as claimed in any one of claims 1 to 6.

8. An electronic device, characterized in that: Comprising a power supply as claimed in claim 7.

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