ENERGY SUPPLY SYSTEM

Abstract

Energy supply system (100) with: - a first battery (20); - a second battery (23); - a voltage converter (10) with several switching elements (31, 32, 33, 34), wherein the switching elements (31, 32, 33, 34) are designed to bidirectionally convert a voltage between the first battery (20) and / or the second battery (23) and an output line (26) and to switch a connection between the first battery (20) and the second battery (23) to the output line (26) between a series and a parallel connection; and - a controller (60) designed to switch the multiple switching elements (31, 32, 33, 34) on or off in accordance with pulse width modulation control, wherein - the output line (26) has a first electrical line (12) and a second electrical line (11) of lower potential than the first electrical line (12), - the multiple switching elements (31, 32, 33, 34) have a first, second, third and fourth switching element (31, 32, 33, 34) which are connected in series from the first to the second electrical line (12, 11), - the first battery (20) is connected in parallel to the third and fourth switching elements (33, 34), - the second battery (23) is connected in parallel to the second and third switching elements (32, 33), - the controller (60) then, if a total high-level period, which is a total period of a first high-level period and a second high-level period, is shorter than a duty cycle period, is designed to control phases of pulse-width modulation control signals such that the first high-level period and the second high-level period do not overlap, in order to reduce noise by bringing the frequency of the electromagnetic noise of the voltage converter outside the range audible to humans, wherein the first high-level period is a high-level period of a first pulse-width modulation control signal for controlling a first voltage conversion of a first voltage conversion circuit formed between the first battery (20) and the output line (26),the second high-level period is a high-level period of a second pulse-width modulation control signal for controlling a second voltage conversion of a second voltage conversion circuit formed between the second battery (23) and the output line (26), and the duty cycle period is a total period of low-level periods of the pulse-width modulation control signals and a corresponding number of high-level periods of the pulse-width modulation control signals.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The invention relates to the structure of a power supply system and in particular a controller for a system that has two parallel connected power supplies and converts a voltage via PWM control. 2. State of the art

[0002] It is known to use voltage converters to convert the voltage of a battery by switching switching elements on or off via PWM control. More recently, a power supply system has been proposed that uses a voltage converter composed of four switching elements and features both series and parallel modes (as described, for example, in JP 2013-13234A, also published as US 2014 / 0145694A1). In series mode, the voltage is converted in a state where two batteries are connected in series, using a combination of on / off switching operations of the switching elements. In parallel mode, the voltage is converted in a state where two batteries are connected in parallel, using a combination of on / off switching operations of the switching elements.When the voltage converter used in this type of power supply system is operated in parallel mode, voltage conversion control via the batteries is achieved by switching the switching elements on or off in accordance with two pulse-width modulation (PWM) control signals corresponding to the two batteries. JP 2013-13234A proposes that when this type of voltage converter is operated in parallel mode, a loss of switching element performance is suppressed by changing the phases of the two PWM control signals.

[0003] Furthermore, it is known that in an existing voltage converter that converts the voltage of a battery based on the on / off switching operations of switching elements, electromagnetic noise occurs due to these switching operations. Since the electromagnetic noise is cacophonous when it falls within the human hearing range, a method or the like has been investigated that reduces noise by increasing the carrier frequency of the pulse-width modulation control to raise the frequency of the electromagnetic noise above the human hearing range. However, noise reduction for the power supply system that uses the voltage converter, which performs voltage conversion control via the two batteries by using the two pulse-width modulation control signals, as described in JP 2013-13234A, has not yet been sufficiently investigated.

[0004] DE 10 2015 117 169 A1 (also published as US 2016 / 0 105 126 A1), as a subsequently published prior art, discloses an electrical energy conversion system comprising: a first battery; a second battery; an electrical energy converter comprising a plurality of switching elements and configured for bidirectional step-up or step-down conversion of electrical energy between an output line and each of the first and second batteries according to PWM signals; and a control unit configured to control a first and a second step-up and step-down conversion circuit by generating first and second PWM signals. The first and second step-up and step-down conversion circuits are arranged between each of the first and second batteries and the output line.The first and second PWM signals are signals for controlling boost and buck conversion operation from one of the first and second boost and buck conversion circuits, respectively. The control unit is configured, when the on-times of both the first and second PWM signals are coupled, to perform an overlap phase shift that partially overlaps the on-times of the first and second PWM signals. SUMMARY OF THE INVENTION

[0005] The object of the invention is to provide a power supply system that reduces noise in the power supply system that performs voltage conversion control via two batteries using two pulse width modulation control signals.

[0006] The problem is solved in each case by an energy supply system according to claims 1, 3 and 4. Advantageous further developments are the subject of the dependent claims.

[0007] An energy supply system according to one aspect of the invention comprises: a first battery; a second battery; a voltage converter with multiple switching elements, wherein the switching elements are configured to bidirectionally convert a voltage between the first and / or the second battery and an output line and to switch a connection between the first and second batteries to the output line between a series and a parallel connection; and a controller configured to switch the multiple switching elements on or off in accordance with pulse-width modulation control. The output line has a first electrical conductor and a second electrical conductor at a lower potential than the first electrical conductor. The multiple switching elements comprise a first, second, third, and fourth switching element.which are connected in series from the first to the second electrical line. The first battery is connected in parallel to the third and fourth switching elements. The second battery is connected in parallel to the second and third switching elements. The controller, when a total high-level period, which is the total period of a first high-level period and a second high-level period, is shorter than a duty cycle period, is designed to control phases of pulse-width modulation control signals such that the first high-level period and the second high-level period do not overlap, where the first high-level period is a high-level period of a first pulse-width modulation control signal for controlling a first voltage conversion of a first voltage conversion circuit formed between the first battery and the output line.The second high-level period is a high-level period of a second pulse-width modulation (PWM) control signal for controlling a second voltage conversion in a second voltage conversion circuit formed between the second battery and the output line, and the duty cycle period is a total of low-level PWM control signal periods and a corresponding high-level PWM control signal periods. The controller is further designed to adjust a carrier frequency of the PWM control signals such that twice the carrier frequency lies within the human hearing range, and to control the phases of the PWM control signals such that the frequency of any generated electromagnetic noise is shifted to a range outside the human hearing range.

[0008] According to the above aspect, if each of the periods of high level of the pulse width modulation control signals is less than 50% of the duty cycle period, the controller can be designed to control the phases of the pulse width modulation control signals such that the periods of high level appear alternately once every half-cycle of the duty cycle period.

[0009] A power supply system according to a second aspect of the invention comprises: a first battery; a second battery; a voltage converter with multiple switching elements, wherein the switching elements are configured to bidirectionally convert a voltage between the first and / or the second battery and an output line and to switch a connection between the first and second batteries to the output line between a series and a parallel connection; and a controller configured to switch the multiple switching elements on or off in accordance with pulse-width modulation control. The output line has a first electrical conductor and a second electrical conductor at a lower potential than the first electrical conductor. The multiple switching elements comprise a first, second, third, and fourth switching element.which are connected in series from the first to the second electrical line. The first battery is connected in parallel to the third and fourth switching elements. The second battery is connected in parallel to the second and third switching elements. The controller is designed, when a total high-level period (the total period of a first high-level period and a second high-level period) is shorter than a duty cycle period, to perform phase control by mixing a first control with a second control, where the first high-level period is a high-level period of a first pulse-width modulation control signal for controlling a first voltage conversion of a first voltage conversion circuit formed between the first battery and the output line.the second high-level period is a high-level period of a second pulse-width modulation control signal for controlling a second voltage conversion of a second voltage conversion circuit formed between the second battery and the output line; the duty cycle period is a total period of each of the low-level periods of the pulse-width modulation control signals and a corresponding high-level period of the pulse-width modulation control signals; the first control is a control in which phases of the pulse-width modulation control signals are controlled such that the first high-level period of the first pulse-width modulation control signal and the second high-level period of the second pulse-width modulation control signal overlap; and the second control is a control in which the phases of the pulse-width modulation control signals are controlled such thatthat the first period of high level of the first pulse-width modulation control signal and the second period of high level of the second pulse-width modulation control signal do not overlap. The controller is further designed to set a carrier frequency of the pulse-width modulation control signals such that twice the value of the carrier frequency lies within the human hearing range, and to control the phases of the pulse-width modulation control signals such that the frequency of a generated electromagnetic noise is shifted into a range outside the human hearing range.

[0010] A power supply system according to a third aspect of the invention comprises: a first battery; a second battery; a voltage converter with multiple switching elements, wherein the switching elements are configured to bidirectionally convert a voltage between the first and / or the second battery and an output line and to switch a connection between the first and second batteries to the output line between a series and a parallel connection; and a controller configured to switch the multiple switching elements on or off in accordance with pulse-width modulation control. The output line has a first electrical conductor and a second electrical conductor at a lower potential than the first electrical conductor. The multiple switching elements comprise a first, second, third, and fourth switching element, which are connected in series from the first to the second electrical conductor.The first battery is connected in parallel to the third and fourth switching elements. The second battery is connected in parallel to the second and third switching elements. The controller is designed to, during a period in which a first pulse-width modulation (PWM) control signal for controlling a first voltage conversion of a first voltage conversion circuit formed between the first battery and the output line is at a low level, to raise a second PWM control signal for controlling a second voltage conversion of a second voltage conversion circuit formed between the second battery and the output line from a low level to a high level and then back to a low level.The controller is further designed to adjust a carrier frequency of the pulse width modulation control signals such that twice the value of the carrier frequency lies within the human hearing range, and to control the phases of the pulse width modulation control signals such that the frequency of a generated electromagnetic noise is shifted into a range outside the human hearing range.

[0011] In the above aspect, the controller can be designed to generate the first pulse width modulation control signal based on a first triangle wave and a first threshold, to generate the second pulse width modulation control signal based on a second triangle wave and a second threshold, and to increase a frequency of the second triangle wave above a frequency of the first triangle wave during the period in which the first pulse width modulation control signal is at a low level.

[0012] In the above aspect, the controller can be designed to increase the frequency of the second triangle wave above the frequency of the first triangle wave during the period in which the first pulse width modulation control signal is at a low level, such that a period in which a value of the second triangle wave exceeds the second threshold and a period in which the value of the second triangle wave does not exceed the second threshold appear.

[0013] According to the above aspects of the invention, noise in a power supply system that uses a voltage converter which performs voltage conversion control via two batteries using two pulse width modulation control signals can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The features and advantages, as well as the technical and industrial significance of exemplary embodiments of the invention, are described below with reference to the accompanying drawings, in which identical elements are designated with the same reference numerals. The drawings show: Fig. 1 a system circuit diagram showing the configuration of a power supply system of the invention mounted on an electric vehicle; Fig. 2 an illustration to demonstrate the current flow while the first choke coil is charged by a first battery in basic operations of the power supply system of the invention; Fig. 3 An illustration to demonstrate the current flow while electrical energy with which the first choke coil is charged is output to an output line in the basic operations of the power supply system of the invention; Fig. 4 An illustration to demonstrate the current flow while a second choke coil is charged by a second battery in basic operations of the power supply system of the invention; Fig. 5 An illustration to demonstrate the current flow while electrical energy, with which the second choke coil is charged, is output to the output line in the basic operations of the power supply system of the invention; Fig. 6 a timing diagram to illustrate pulse width modulation control signals and switching element control signals during the basic operation of the power supply system of the invention; Fig. 7 a timing diagram to illustrate the pulse width modulation control signals and the switching element control signals, while the phase of PWM2 is shifted by 180 degrees or 150 degrees from the phase of PWM1 in the power supply system of the invention; Fig. Figure 8 illustrates the current flow while the second choke coil is being charged and electrical energy is being drawn from the first battery during operation. Fig. 7 is issued; Fig. 9. An illustration to demonstrate the current flow while the first choke coil is being charged and electrical energy is being drawn from the second battery during operation. Fig. 7 is issued; Fig. 10 a timing diagram to illustrate the timings of the pulse width modulation control signals and the switching element control signals while the phase of PWM2 is shifted by 180 degrees from the phase of PWM1, in the case that the duty cycle of PWM2 is greater than or equal to 50% and the total period of a first period of high level of PWM1 and a second period of high level of PWM2 is shorter than a duty cycle period, in the power supply system of the invention; Fig. 11 a timing diagram to illustrate the pulse width modulation control signals and the switching element control signals, while the phase of the second pulse width modulation control signal is changed in accordance with a sequence in the power supply system of the invention; and Fig. 12 a time diagram to illustrate the pulse width modulation control signals and the switching element control signals while the frequency of a second triangle wave in the power supply system of the invention is temporarily increased. DETAILED DESCRIPTION OF THE EXECUTION FORMS

[0015] An energy supply system 100 according to the invention is described below with reference to the accompanying drawings. In the description of the following embodiment, the energy supply system 100 provides electrical energy for a motor-generator 50 of an electric vehicle 200. Alternatively, the energy supply system 100 can provide electrical energy for a motor or motor-generator of a general-purpose machine.

[0016] The energy supply system 100 according to the invention has, as shown in Fig. Figure 1 shows a first battery 20, a second battery 23, a voltage converter 10, and a controller 60. The voltage converter 10 has several switching elements 31 to 34, a first choke coil 22, a second choke coil 25, a first capacitor 21, a second capacitor 24, and an output line 26. The controller 60 switches the several switching elements 31 to 34 on or off. A smoothing capacitor 41 and an inverter 40 are connected to the output line 26. The motor-generator 50 is connected to the inverter 40. The motor-generator 50 powers the electric vehicle 200. The dashed lines in the Fig. 1 designates signal lines.

[0017] The output line 26 of the voltage converter 10 has a high-voltage electrical line 12 and an electrical reference line 11. The high-voltage electrical line 12 outputs a high voltage, which is amplified by the voltage converter 10. The electrical reference line 11 is connected to the negative terminal of each of the batteries 20, 23 and has a lower potential than the high-voltage electrical line 12. The several switching elements 31 to 34 are connected in series from the high-voltage electrical line 12 to the electrical reference line 11. Diodes 35 to 38 are connected in antiparallel to the switching elements 31 to 34. The voltage converter 10 has a first electrical line 13 and a second electrical line 14. The first electrical line 13 connects a second node 17 to the electrical reference line 11. The second node 17 is located between switching element 32 and switching element 33.The second electrical line 14 connects a first junction 16 with a third junction 18. The first junction 16 is located between switching element 31 and switching element 32. The third junction 18 is located between switching element 33 and switching element 34. The first battery 20 and the first choke 22 are connected in series on the first electrical line 13. The second battery 23 and the second choke 25 are connected in series on the second electrical line 14. The first capacitor 21 is connected in parallel with the first battery 20. The second capacitor 24 is connected in parallel with the second battery 23. The smoothing capacitor 41 is connected between the high-voltage electrical line 12 and the electrical reference line 11. In this way, the first battery 20 is connected in parallel with switching elements 33 and 34, and the second battery 23 is connected in parallel with switching elements 32 and 33.

[0018] A voltage sensor 61 is installed in the first battery 20 and detects a voltage VB1. A voltage sensor 71 is installed in the second battery 23 and detects a voltage VB2. A voltage sensor 64 is connected between the first electrical line 13 and the electrical reference line 11 and detects a voltage VL1 between both ends of the first capacitor 21. A voltage sensor 74 is connected to the second electrical line 14 and detects a voltage VL2 between both ends of the second capacitor 24. A voltage sensor 75 is connected between the high-voltage electrical line 12 and the electrical reference line 11 and detects a voltage VH between both ends of the smoothing capacitor 41.

[0019] The inverter 40 internally comprises several switching elements (not shown) and converts the direct current output from the output line 26 of the voltage converter 10 into a three-phase (U, V, W) alternating current by switching the switching elements on and off. The three-phase alternating current (hereinafter referred to as three-phase current) is then supplied to output lines 43, 44, and 45 of the respective phases. The output line 26 consists of the electrical reference line 11 and the high-voltage electrical line 12. The U-phase, V-phase, and W-phase output lines 43, 44, and 45 are connected to the motor-generator 50. An output shaft 51 of the motor-generator 50 is connected to a gearbox 52. Axles 53 are connected to the gearbox 52. Wheels 54 are attached to the axles 53.

[0020] The controller 60 is a computer comprising a CPU, a memory unit, and a device and sensor interface. The CPU performs arithmetic and information processing. The memory unit stores control programs and control data. Devices and sensors are connected to the device and sensor interface. The CPU, the memory unit, and the device and sensor interface are interconnected via a data bus. The switching elements 31 to 34 of the voltage converter 10 are connected to the controller 60 via the device and sensor interface and switch on or off in response to commands from the controller 60. The voltage sensors 61, 64, 71, 74, and 75 are also connected to the controller 60 via the device and sensor interface. Data acquired by the sensors is transmitted to the controller 60.A high-voltage command value VH* and a current command value I* are given to controller 60 from another controller. Basic operation of the voltage converter 10

[0021] The voltage converter 10 is capable of bidirectionally converting a voltage between the first and / or second battery 20, 23 and the output line 26 in order to increase the voltage of at least one of the first battery 20 and the second battery 23 and supply the increased voltage to the output line 26, or to decrease the voltage of the output line 26 and charge the first and / or second battery 20, 23 with the decreased voltage by switching the on / off switching pattern of the four switching elements 31 to 34. Furthermore, it is capable of switching the connection of the first and second battery 20, 23 to the output line 26 between a series connection and a parallel connection. The basic operations of the voltage converter 10 in the case where the first and second battery 20, 23 are connected in parallel are described below with reference to the Fig. 2, Fig. 3 to Fig. As described in section 4, the first switching element 31 is designated S1(31) using the symbol S1 and the reference numeral 31, the second switching element 32 is designated S2(32) using the symbol S2 and the reference numeral 32, the third switching element 33 is designated S3(33) using the symbol S3 and the reference numeral 33, and the fourth switching element 34 is designated S4(34) using the symbol S4 and the reference numeral 34. The diodes 35 to 38, which are each connected antiparallel to the switching elements 31 to 34, are designated D1(35) to D4(38) using the symbols D1 to D4 and the reference numerals 35 to 38. Similarly, the first battery 20 and the second battery 23 are designated as B1(20) and B2(23) respectively, using the symbols B1, B2 and the reference numerals 20, 23, and the first and second capacitors 21, 24 are designated as C1(21) and C2(23) respectively, using the symbols C1, C2 and the reference numerals 21, 24.C2(24) is designated, and the first and second choke coils 22, 25 are designated using the symbols L1, L2 and the reference numerals 22, 25 as L1(22) and L2(25), respectively. Each of the switching elements 31 to 34 is a semiconductor element, such as an IGBT, which in an on-state allows current flow only in the direction of the arrow in the . Fig. 1 enables and does not allow current flow in the direction opposite to the arrow direction. In the Fig. 3, Fig. 4, Fig. 6 and Fig. To illustrate the on / off states of switching elements 31 to 34, switching elements 31 to 34 are shown as simple on / off switches. Boost / bump operation in the parallel-connected B1(20) and B2(23)

[0022] The following describes the boost / drag operation for the case where B1(20) and B2(23) are connected in parallel in the voltage transformer 10, with reference to the Fig. 2, Fig. 3, Fig. 4 to Fig. 5 described.

[0023] First, a voltage conversion takes place between B1(20) and the output line 26 with reference to the Fig. 2 and Fig. 3 described. A circuit R1, through which current flows in the sequence B1(20), L1(22), S3(33), S4(34) and B1(20), is formed by switching on the pair of S3(33) and S4(34) and switching off the pair of S1(31) and S2(32), and electrical energy output by B1(20) returns through circuit R1 and charges L1(22). Subsequently, as in Fig. Figure 3 shows a circuit R5 (indicated by the solid line) through which current flows in the sequence B1(20), L1(22), D2(36), D1(35), high-voltage electrical line 12, electrical reference line 11 and B1(20), and a circuit R7 (indicated by the dashed line) through which current flows in the sequence high-voltage electrical line 12, S1(31), S2(32), L1(22), B1(20), electrical reference line 11 and high-voltage electrical line 12, formed by switching off the pair of S3(33) and S4(34) and switching on the pair of S1(31) and S2(32), whereby electrical energy charged in L1(22) is given to the output line 26 via the circuit R5 and B1(20) is charged via the circuit R7 with the electrical energy regenerated by the motor generator 50 (indicated by the dashed line).When the pair S1(31) and S2(32) is switched off during regeneration, the electrical energy stored in L1(22) is recovered by B1(20) via a circuit in the reverse direction to circuit R1. The voltage VB1 of B1(20) is raised and output to output line 26 by alternately repeating a first on-period and a first off-period. During the first on-period, the pair S3(33) and S4(34) is switched on while at least one of S1(31) and S2(32) is switched off. During the first off-period, S1(31) and S2(32) are switched on while at least one of S3(33) and S4(34) is switched off.

[0024] In this way, a bidirectional boost chopper circuit is formed in the voltage converter 10. In the bidirectional boost chopper circuit, the pair of S3(33) and S4(34) forms switching elements (equivalent to the first elements of the lower arm) that are switched on when L1(22) is charged by B1(20), and the pair of S1(31) and S2(32) forms switching elements (equivalent to the first elements of the upper arm) that are switched on when electrical energy is output. The boost chopper circuit exhibits the characteristics described in the Fig. 2 described circuit R1 and the one with reference to the Fig. The circuits R5 and R7 described in section 3 form a first voltage conversion circuit. This first voltage conversion circuit is formed between B1(20) and the output line 26 and performs a first voltage conversion between B1(20) and the output line 26.

[0025] The total period of the first on-period and the first off-period in the first voltage conversion circuit is one duty cycle period. The ratio of the first on-period to the duty cycle period describes a first duty cycle D1. In the first voltage conversion circuit, at the time when the voltage VB1 of B1(20) is raised to the high-voltage command value VH*, the pair of S1(31) and S2(32) (equivalent to the first elements of the upper arm) and the pair of S3(33) and S4(34) (equivalent to the first elements of the lower arm) are subjected to pulse-width modulation (PWM) control such that the ratio between the first duty cycle D1, the high-voltage command value VH*, and the voltage VB1 of B1(20) can be described by the following mathematical equation (1). VH*=[1 / (1−D1)]×VB1

[0026] In actual control, the pair of S1(31) and S2(32) (equivalent to the first elements of the upper arm) and the pair of S3(33) and S4(34) (equivalent to the first elements of the lower arm) are subjected to PWM control such that VL1, which describes the voltage between the two ends of C1(21), is used instead of VB1, the ratio being described by the following mathematical equation (2). VH*=[1 / (1−D1)]×VL1

[0027] A control signal for this PWM control is referred to as a first pulse width modulation control signal.

[0028] Below is a second voltage transformation between B2(23) and the output line 26 with reference to the Fig. 4 and Fig. 5 described. As in Fig. As shown in Figure 4, a circuit R2 is formed through which current flows in the sequence B2(23), L2(25), S2(32), S3(33), and B2(23) by switching on the pair of S2(32) and S3(33) and switching off the pair of S1(31) and S4(34), whereby electrical energy output by B2(23) returns via the circuit R2 and charges L2(25). Subsequently, as shown in Fig. Figure 5 shows a circuit R6 (indicated by the solid line) through which current flows in the sequence B2(23), L2(25), D1(35), high-voltage electrical line 12, electrical reference line 11, D4(38) and B2(23), and a circuit R8 (indicated by the dashed line) through which current flows in the sequence high-voltage electrical line 12, S1(31), L2(25), B2(23), S4(34), electrical reference line 11 and high-voltage electrical line 12, formed by switching off the pair of S2(32) and S3(33) and switching on the pair of S1(31) and S4(34), whereby the electrical energy charged in L2(25) is output to output line 26 via circuit R6 and B2(23) is charged via circuit R8 (indicated by the dashed line) with the electrical energy regenerated by motor generator 50.When the pair S1(31) and S4(34) is switched off during regeneration, the electrical energy stored in L2(25) is recovered by B2(23) via a circuit in the reverse direction to circuit R2. The voltage VB2 of B2(23) is raised and output to output line 26 by alternately repeating a second on-period and a second off-period. During the second on-period, the pair S2(32) and S3(33) is switched on while S1(31) and / or S4(34) are switched off. During the second off-period, S1(31) and S4(34) are switched on while S2(32) and / or S3(33) are switched off.

[0029] In this way, a bidirectional boost chopper circuit is formed in the voltage converter 10. In the bidirectional boost chopper circuit, the pair of S2(32) and S3(33) forms switching elements (equivalent to the second elements of the lower arm) that are switched on when L2(25) is charged by B2(23), and the pair of S1(31) and S4(34) forms switching elements (equivalent to the second elements of the upper arm) that are switched on when electrical energy is output. The boost chopper circuit exhibits the characteristics described in the Fig. 4 described circuit R2 and the one with reference to the Fig. The circuits described in section 5, R6, and R8 are connected and form a second voltage conversion circuit. The second voltage conversion circuit is formed between B2(23) and the output line 26 and performs a second voltage conversion between B2(23) and the output line 26.

[0030] The combined period of the second on-period and the second off-period in the second voltage conversion circuit describes a duty cycle period. The ratio of the second on-period to the duty cycle period describes a second duty cycle D2. In the second voltage conversion circuit, at the time when the voltage VB2 of B2(23) is raised to the high-voltage command value VH*, the pair of S1(31) and S4(34) (equivalent to the second elements of the upper arm) and the pair of S2(32) and S3(33) (equivalent to the second elements of the lower arm) are subjected to pulse-width modulation (PWM) control such that the ratio between the second duty cycle D2, the high-voltage command value VH*, and the voltage VB2 of B2(23) can be described by the following mathematical equation (3). VH*=[1 / (1−D2)]×VB2

[0031] In actual control, the pair of S1(31) and S4(34) (equivalent to the second elements of the upper arm) and the pair of S2(32) and S3(33) (equivalent to the second elements of the lower arm) are subjected to PWM control such that VL2, which describes the voltage between the two ends of C2(24), is used instead of VB2, the ratio being described by the following mathematical equation (4). VH*=[1 / (1−D2)]×VL2

[0032] A control signal for this PWM control is referred to as a second pulse width modulation control signal.

[0033] Generation of pulse width modulation control signals and switching element control signals and basic operation of the voltage converter

[0034] Below are a generation of the first pulse width modulation control signal (PWM1) and the second pulse width modulation control signal (PWM2) and a method for generating switching element control signals SS1 to SS4 from the pulse width modulation control signals (PWM1, PWM2) with reference to (a) to (j) in the Fig. 6 described. The switching element control signals SS1 to SS4 are each used to switch the switching elements S1(31) to S4(34) on or off.

[0035] Within the controller 60, as shown in (a) and (d), the Fig. Figure 6 shows a first triangle wave 81 and a second triangle wave 83. The first triangle wave 81 has a predetermined frequency and is used to generate the first pulse-width modulation control signal (PWM1). The second triangle wave 83 is used to generate the second pulse-width modulation control signal (PWM2). In the present embodiment, shown in (a) to (j) of the Fig. As shown in Figure 6, the frequency (period) of the first triangle wave 81 and the frequency (period) of the second triangle wave 83 are equal, and this frequency is called the carrier frequency. The x-axes from (a) to (j) in the Fig. Figure 6 describes the time or phase angle of each of the triangular waves 81, 83, and one period corresponds to a phase angle of 360 degrees. One period of both the first and second triangular waves 81, 83 is called the duty cycle period. t0 to t24 on the x-axes from (a) to (j) in the Fig. The 6 describe time, and the interval between the times is a time obtained by dividing a period, or duty cycle period, into 12 equal sections. The interval between the times (such as between time t0 and time t1) is called a section. Consequently, 12 sections correspond to one duty cycle period, and one period of both the first and second triangular wave 81, 83 corresponds to a phase angle of 360 degrees.

[0036] Subsequently, a straight line 82 is defined between the crests and troughs of the first triangular wave 81, and a straight line 84 is defined between the crests and troughs of the second triangular wave 83. The height (threshold) of the straight line 82 is determined such that the ratio of one period (high-level period) in which the value of the first triangular wave 81 exceeds the value of the straight line 82 in the duty cycle period is the first duty cycle D1, as described above. Similarly, the height (threshold) of the straight line 84 is determined such that the ratio of one period (high-level period) in which the value of the second triangular wave 83 exceeds the value of the straight line 84 in the duty cycle period is the second duty cycle D2, as described above.By determining the triangle waves 81, 83 and the straight lines (thresholds) 82, 84 in this way, the first pulse width modulation control signal (PWM1) is obtained, in which the ratio of the period in which the signal has the high level in the duty cycle period assumes the first duty cycle D1, which is in (b) of the . Fig. 6 is shown, and the second pulse width modulation control signal (PWM2), where the ratio of the period in which the signal has the high level in the duty cycle period assumes the second duty cycle D2, as shown in (e) of the Fig. 6 shown, generated.

[0037] In PWM1, the duty cycle period, as in (b) of the Fig. Figure 6 shows 12 sections from time t1 to time t12, wherein a first high-level period, in which the signal is high, has four sections from time t4 to time t8, a first low-level period, in which the signal is low, has eight sections from time t0 to time t4 and from time t8 to time t12, and the first duty cycle D1 = 4 / (4 + 8) = (4 / 12) < 50%. PWM2 is, as in (e) of the Fig. 6 shown, equal to PWM1. Regarding an inverted signal / PWM1 of PWM1, one period in which the signal has the low level, as in (c) of the Fig. Figure 6 shows four sections from time t4 to time t8, and one period in which the signal has the high level, eight sections from time t0 to time t4 and from time t8 to time t12. / PWM2 as an inverted signal of PWM2 is equal to / PWM1. That is, in the operational sequences shown in (a) to (j) of the Fig. As shown in Figure 6, the times at which PWM1 and PWM2 assume the high or low level are the same, i.e., the phase difference between PWM1 and PWM2 is zero, and the duty cycles D1, D2 are equal to (4 / 12) < 50%.

[0038] The switching element control signals SS1 to SS4 for switching on or off S1(31) to S4(34) are described by the following logic equations using the pulse width modulation control signals PWM1, / PWM1, PWM2, / PWM2 described above. SS1:( / PWM1)or( / PWM2) SS2:( / PWM1)or( / PWM2) SS3: (PWM1) or (PWM2) SS4:(PWM1)or( / PWM2)

[0039] In the cases described in (a) to (j) Fig. The operational processes shown in 6 are as described in (g) of the Fig. As shown in Figure 6, SS1 is a signal that, in one period (duty cycle period), switches S1(31) on during the four sections from time t0 to time t4, switches S1(31) off during the four sections from time t4 to time t8, and switches S1(31) on during the four sections from time t8 to time t12, repeatedly in each duty cycle. SS2 is, as shown in (h) of the Fig. Figure 6 shows a signal that constantly switches on S2(32). SS3 is, as in (i) the Fig. Figure 6 shows a signal that switches off S3(33) during the four intervals from time t0 to time t4, switches on S3(33) during the four intervals from time t4 to time t8, and switches off S3(33) during the four intervals from time t8 to time t12, repeatedly in each duty cycle. SS4 is, as shown in (j) of the Fig. Figure 6 shows a signal that constantly switches on S4(34). Between time t4 and time t8 in (a) to (j) of the Fig. 6 consequently switches off S1(31), consequently switches on S2(32), S3(33) and S4(34), the in the Fig. 2 shown circuit R1 and the one in the Fig. In circuit 4 shown, R2 is simultaneously formed, L1(22) is charged by B1(20) and L2(25) is charged by B2(23). From time t0 to time t4 and from time t8 to time t12, S1(31), S2(32) and S4(34) switch on, S3(33) switches off, and the components in the circuit are charged. Fig. The circuits R5, R7 and the one shown in the 3 circuits are shown. Fig. In the circuits shown in 5, R6 and R8 are formed simultaneously, and the electrical energy with which L1(22) is charged and the electrical energy with which L2(25) is charged are simultaneously output to the output line 26.

[0040] In the operational processes in (a) to (j) of the Fig. 6 is, as indicated by the black triangle markings in (g) and (i) of the Fig. Figure 6 shows the number of switching operations of both S1(31) and S3(33) from the on state to the off state or from the off state to the on state during one period (one phase angle of 360 degrees) of both the first and the second triangle wave 81, 83, or one duty cycle period (from time t0 to time t12), which is two. The times of the switching operations are the same.Consequently, in the voltage transformer 10, since components such as C1 (21), L1 (22), C2(24), L2(25) and a busbar receive changes in the Lorentz force and an electrostatic force once at time t4 and once at time t8, twice in total, during one period (a phase angle of 360 degrees) of both the first and the second triangle wave 81, 83 or one duty cycle period (from time t4 to time t12) and, as a result, a vibration occurs in these components twice in one duty cycle period (from time t0 to time t12), a vibration or noise with a frequency twice as high as the frequency (carrier frequency) of both the first and the second triangle wave 81, 83 occurs.If the frequency (carrier frequency) of both the first and second triangle waves is 81, 83 10 kHz, the frequency of the generated electromagnetic noise is 20 kHz and is a frequency close to the upper limit of the human hearing range, so that it may be perceived as noise or interference. <Change of phases of PWM1 and PWM2>

[0041] The following are the operating sequences and the generated noise at the time when the phases of the first and second pulse width modulation control signals PWM1, PWM2 differ from the zero-phase-difference operating sequences shown in (a) to (j) of the Fig. Figure 6 shows how the operating procedures are changed with a phase difference of 180 degrees (half a duty cycle period (time t0 to time t12)), with reference to (a) to (j) in the Fig. 7 described.

[0042] The second triangle wave for generating PWM2 is, as in (a) and (d) of the Fig. 7 shown, set to a second triangle wave 85, where the phase difference Δϕ1 to the phase of the first triangle wave 81 for generating PWM1 is 180 degrees. More precisely, the one shown in (d) of the Fig. The second triangle wave 83 shown in Figure 6 is shifted by six sections over time such that the peaks of the wave crests of the second triangle wave 85, shown in (d) of the Fig. As shown in Figure 7, the time intervals t12 and t24 coincide, such that the time difference from the peaks of the wave crests of the first triangle wave 81 is six intervals (t12 - t6), (t24 - t18). Consequently, as shown in (b) and (e), the Fig. Figure 7 shows that the phase of PWM2 is shifted by 180 degrees, i.e., six sections or half of 12 sections of the duty cycle period over time, from the phase of PWM1. Similarly, the phase of PWM2 is shifted by 180 degrees, i.e., six sections or half of 12 sections of the duty cycle period over time, from the phase of PWM1. The first duty cycle D1 of PWM1 and the second duty cycle D2 of PWM2 are each (4 / 12) < 50%, as in the case of the operating sequences described with reference to (a) to (j) in the Fig. 6 are described. The first period of high level, in which PWM1 exhibits the high level, extends, as in (b) and (e) of the Fig. Figure 7 shows the first period of high level from time t4 to time t8, whereas the second period of high level, in which PWM2 exhibits the high level, extends from time t0 to time t4 and from time t10 to time t12. Consequently, the first period of high level of PWM1 and the second period of high level of PWM2 do not overlap, and both PWM1 and PWM2 exhibit the low level from time t2 to time t4 and from time t8 to time t10.In this way, if the total period (eight sections) of the first high-level period of PWM1 (four sections) and the second high-level period of PWM2 (four sections) is shorter than the duty cycle period (12 sections), more precisely, if the total numerical value (33 + 33 = 66) of the numerical value (4 / 12 = 1 / 3 = 33%, and the numerical value is 33) of the first duty cycle D1 of PWM1 in percent and the numerical value (4 / 12 = 1 / 3 = 33%, and the numerical value is 33) of the second duty cycle D2 of PWM2 in percent is less than the numerical value (12 / 12 = 100%, and the numerical value is 100) of the duty cycle period in percent, and if the phase of PWM2 is by 180 degrees, i.e., six sections or half of 12 sections of the The duty cycle period, which shifts the phase of PWM1, does not affect the first high-level period of PWM1 and the second high-level period of PWM2. That is,The phases of PWM1 and PWM2 are controlled in such a way that the respective periods of high level appear alternately every half-period of the duty cycle period.

[0043] The control signals SS1 to SS4 for switching S1(31) to S4(34) on or off at this time are calculated using the mathematical equations (5) to (8) described above and are shown in (g) to (j) of the Fig. 7 shown. SS1 is, as in (g) the Fig. Figure 7 shows a signal that continuously switches on S1(31). SS2 is, as in (h) the Fig. Figure 7 shows a signal that, within one period (duty cycle period), switches S2(32) on during the four sections from time t0 to time t4, switches S2(32) off during the four sections from time t4 to time t8, and switches S2(32) off during the four sections from time t8 to time t12, repeatedly in each duty cycle. SS3 is, as in (i) of the Fig. Figure 7 shows a signal that switches S3(33) on during the two periods from time t0 to time t2, switches S3(33) off from time t2 to time t4, switches S3(33) on from time t4 to time t8, switches S3(33) off from time t8 to time t10, and switches S3(33) on from time t10 to time t12, repeatedly in each duty cycle. SS4 is, as in (j) of the Fig. Figure 7 shows a signal that switches off S4(34) from time t0 to time t2, switches on S4(34) from time t2 to time t10, and switches off S4(34) from time t10 to time t12, repeatedly in each duty cycle. Consequently, from time t0 to time t2 and from time t10 to time t12 in (a) to (j) of the Fig. 7, S1(31) to S3(33) switched on, S4(34) switched off, the circuits R5, R7, R2, as in Fig. As shown in Figure 8, electrical energy is generated simultaneously, with which L1(22) is charged by B1(20), output via circuit R5 to output line 26, and L2(25) is charged by B2(23). From time t2 to time t4 and from time t8 to time t10, S1(31), S2(32) and S4(34) are switched on and S3(33) is switched off, which are in the Fig. The circuits R5, R7 and the one shown in the 3 circuits are shown. Fig. In the circuits R6 and R8 shown in Figure 5, electrical energy is simultaneously generated, charging L1(22) and charging L2(25), and simultaneously output to output line 26. From time t4 to time t8, S1(31), S3(33), and S4(34) are switched on and S2(32) is switched off, as shown in Figure 5. Circuit R1 and circuits R6 and R8 are simultaneously generated, and electrical energy is simultaneously output to output line 26. From time t4 to time t8, S1(31), S3(33), and S4(34) are switched on and S2(32) is switched off. Fig. 9 shown, simultaneously generated, electrical energy with which L2(25) is charged by B2(23), output via the circuit R6 to the output line 26, and L1(22) is charged by B1(20).

[0044] In the cases described in (a) to (j) Fig. The operating sequences shown in 7 change as indicated by the black triangle markings in (h) to (j) of the Fig. 7 shown, during one period (a phase angle of 360 degrees) of both the first and second triangle wave 81, 85 or during one duty cycle period (from time t0 to time t12), S2(32) at times t4 and t8 from the on state to the off state or from the off state to the on state, S3(33) at times t2, t4, t8 and t10 from the on state to the off state or from the off state to the off state, and S4(34) at times t2 and t10 from the on state to the off state or from the off state to the on state. Consequently, during the operating processes in the voltage converter 10, a vibration occurs four times at times t2, t4, t8 and t10 during one duty cycle period (from time t0 to time t12), so that a vibration or noise with a frequency that is four times higher than the frequency (carrier frequency) of both the first and the second triangle wave 81, 85 is evident.If the frequency (carrier frequency) of both the first and second triangle waves is 81, 83 10 kHz, the frequency of a generated electromagnetic noise is 40 kHz, and this frequency is a frequency that is above the upper limit of the human hearing range, so that it is not perceived by humans as noise.In this way, if the phase difference Δϕ1 of the phase of the second triangle wave 85 for generating PWM2 with respect to the phase of the first triangle wave 81 for generating PWM1 is set to 180 degrees, provided that each of the duty cycles D1, D2 of PWM1 and PWM2 is less than or equal to 50%, the frequency of the electromagnetic noise generated by the voltage converter 10 becomes four times higher than the frequency (carrier frequency) of both the first and second triangle waves 81, 85, and the frequency of the generated electromagnetic noise is shifted into a range outside the human hearing range, thus reducing the noise generated by the voltage converter 10. That is, by changing the phase of PWM2 with respect to the phase of PWM1, a beneficial noise reduction effect equivalent to doubling the carrier frequency can be achieved.

[0045] The above description assumes that the phase difference of the second triangle wave 85 for generating PWM2 is set to 180 degrees relative to the first triangle wave 81. However, as long as a phase difference does not cause an overlap of the first period of high level of PWM1 and the second period of high level of PWM2, the phase of the first triangle wave 81 and the phase of the second triangle wave can be shifted from each other such that the phase difference is different from 180 degrees. A second triangle wave 85' can, for example, be generated as in (d) of the Fig. As shown in Figure 7, the phase of the second triangle wave used to generate PWM2 is shifted by a phase difference Δϕ1' (150 degrees), i.e., five segments over time, from the phase of the first triangle wave 81 used to generate PWM1. Consequently, the phases of PWM2 and PWM2 are, as shown in (e) and (f) of the Fig. Figure 7 shows the phases of PWM1 and / PWM1 shifted by 150 degrees (five sections over time). The switching element control signals SS1, SS2 for turning S1(31) and S2(32) on or off at this time are the same as those in the case of the second triangle wave 85, as shown by the dashed lines in (g) and (h) of the Fig. Figure 7 shows the switching element control signal SS3 for switching S3(33) on or off, which in the case of the second triangle wave 85 changes from the on state to the off state or from the off state to the on state at times t2 and t10, changes from the on state to the off state or from the off state to the on state at times t1 and t9, a vibration occurs four times at times t1, t4, t8 and t9 in one duty cycle period (from time t0 to time t12), and, as in the case of the second triangle wave 85, a vibration or noise appears with a frequency that is four times higher than the frequency (carrier frequency) of both the first and the second triangle wave 81, 85'.Consequently, in this case too, as in the case of the second triangle wave 85, noise can be reduced by shifting the frequency of the electromagnetic noise generated by the voltage converter 10 into a range outside the human hearing range.

[0046] In the above references to (a) to (j) the Fig. The operating procedures described in section 7 are based on the assumption that the first duty cycle D1 of PWM1 and the second duty cycle D2 of PWM2 are each (4 / 12) < 50%. However, as long as the total period (eight segments) of the first high-level period (four segments) of PWM1 and the second high-level period (four segments) of PWM2 is shorter than the duty cycle period (12 segments), the phases of PWM1 and PWM2 can be synchronized such that the first high-level period of PWM1 and the second high-level period of PWM2 do not overlap. More precisely, if the total numerical value of the first duty cycle D1 of PWM1 in percent and the numerical value of the second duty cycle D2 of PWM2 in percent is less than 100, i.e.,Since the numerical value of the duty cycle period is in percent, the phases of PWM1 and PWM2 can be adjusted so that the phase of the first period of high level of PWM1 and the phase of the second period of high level of PWM2 do not overlap.

[0047] If, for example, as in (a) the Fig. 10 shows the height (threshold) of a straight line 91, which determines the first duty cycle D1, above the straight line 82 in (a) of the Fig. 7 is raised beyond (the threshold is increased), the duty cycle period is set to 12 sections from time t0 to time t12, the first high-level period of PWM1 has two sections from time t5 to time t7, and a first low-level period of PWM1 has 10 sections from time t0 to time t5 and from time t7 to time t12, the first duty cycle D1 = 2 / (2 + 10) = (2 / 12) < 50%, the height (threshold) of a straight line 92, which determines the second duty cycle D2, is below the straight line 84 in (d) of the Fig. 7 is reduced (the threshold is reduced), the second high-level period of PWM2 has eight sections from time t0 to time t4 and from time t8 to time t12, and a second low-level period of PWM2 has four sections from time t4 to time t8, and the second duty cycle D2 = 8 / (4 + 8) = (8 / 12) > 50%, the total period of the first high-level period of PWM1 and the second high-level period of PWM2 is the sum of the two sections and the eight sections, which is equal to 10 sections, and shorter than 12 sections of the duty cycle period. In this case, as with reference to (a) to (j) in the Fig. 7 described when the second triangle wave 85 is used, whose phase difference to the first triangle wave 81 is 180 degrees, as indicated by the black triangle markings in (h) to (j) of the Fig. 10 shown, during one period (one phase angle of 360 degrees) of both the first and second triangle wave 81, 85 or one duty cycle period (from time t0 to time t12), S2(32) at times t5 and t7 from the on state to the off state or from the off state to the on state, S3(33) at times t4, t5, t7 and t8 from the on state to the off state or from the off state to the on state, and S4(34) at times t4 and t8 from the on state to the off state or from the off state to the on state. Consequently, during the operating processes in the voltage converter 10, a vibration occurs four times at times t4, t5, t7 and t8 during one duty cycle period (from time t0 to time t12), so that a vibration or noise occurs with a frequency that is four times higher than the frequency (carrier frequency) of both the first and the second triangle wave 81, 85.In this way, if one of the duty cycles D1 of PWM1 or D2 of PWM2 is greater than or equal to 50%, but the total period of the first period of high level of PWM1 and the second period of high level of PWM2 is shorter than the duty cycle period, the noise can be reduced by adjusting the phase of PWM2 with respect to the phase of PWM1 so that the first period of high level of PWM1 and the second period of high level of PWM2 do not overlap, by shifting the frequency of the electromagnetic noise of the voltage converter 10 into a range outside the range of human hearing.The above description assumes that the phase difference between PWM1 and PWM2 is set to 180 degrees; however, this phase difference is not limited to 180 degrees as long as the phases can be matched in such a way that the first period of high level from PWM1 and the second period of high level from PWM2 do not overlap. Mixing overlap control with non-overlap control for the first and second pulse width modulation control signals

[0048] In the embodiment described above, the description is based on the assumption that the phases of PWM1 and PWM2 are set such that the phase of the first period of high level of PWM1 and the phase of the second period of high level of PWM2 do not overlap. However, the phase control can be adjusted as shown in (a) to (j) of the Fig. As shown in Figure 11, this is achieved by mixing a first control with a second control. In the first control, the phases of the pulse-width modulation (PWM) control signals are controlled such that the first high-level period of the first PWM control signal (PWM1) and the second high-level period of the second PWM control signal (PWM2) overlap or partially overlap. In the second control, the phases of the PWM control signals are controlled such that the first high-level period of PWM1 and the second high-level period of PWM2 do not overlap. The following describes the case where the first and second control are mixed by changing the phase of PWM2 in accordance with a schedule with respect to the phase of PWM1. Operating sequences are the same as those described with reference to (a) of the Fig. 7 to (j) the Fig. The elements described in section 10 are summarized below.

[0049] The first triangular wave 81 and the straight line 82 (threshold) that is in (a) the Fig. 11 shown are the same as those in (a) of the Fig. 6, and PWM1 and / PWM1, which are in (b) and (c) of the Fig. 11 shown are equal to PWM1 and / PWM1, which are defined with reference to (b) and (c) in the Fig. 6 are described. A second triangular wave for generating PWM2 is, as in (d) of the Fig. Figure 11 shows the second triangle wave 83, whose phase difference to the first triangle wave 81 is zero from time t0 to time t2, and PWM1, / PWM1, PWM2, / PWM2 and SS1 to SS4 during this time exhibit signal waves equal to those in (a) to (j) of the Fig. 6 up.

[0050] At time t2, the controller 60 changes the phase of the second triangle wave from the phase of the initial second triangle wave 83 or first triangle wave 81 to a second triangle wave 86 that is shifted by Δϕ2 (120 degrees). The second triangle wave 86 then begins at time t2 in (d) of the Fig. 11. The second triangular wave 86 assumes a trough at time t4, then a crest at time t10, a trough at time t16, and progresses at time t17. The second triangular wave 86 and the straight line 84 (threshold), which defines the second duty cycle D2 of PWM2, intersect as shown in (d) of the Fig. As shown in Figure 11, the second triangle wave 86 overlaps at times t8 and t12, and its value is higher than the value of the straight line 84 from time t8 to time t12. Consequently, PWM2 has a high level from time t8 to time t12 and a low level during the other periods. PWM1 and PWM2 overlap at time t8 and do not overlap during the other periods (first control).

[0051] During the time interval from time t2 to time t17, in which the second triangle wave 86 lasts, the control signals SS1 to SS4 are used to switch S1(31) to S4(34) on or off, as shown in (g) to (j) of the Fig. The values ​​shown in 11 are calculated using the mathematical equations (5) to (8) described above. SS1 is, as shown in (g) of the Fig. Figure 11 shows a signal that continuously switches on S1(31). SS2 is, as in (h) the Fig. Figure 11 shows a signal that switches S2(32) on from time t2 to time t4, switches S2(32) off from time t4 to time t8, switches S2(32) on from time t8 to time t16, and switches S2(32) off from time t16 to time t17. SS3 is, as in (i) of the Fig. Figure 11 shows a signal that switches off S3(33) from time t2 to time t4, switches on S3(33) from time t4 to time t12, switches off S3(33) from time t12 to time t16, and switches on S3(33) from time t16 to time t17. Furthermore, SS4 is, as shown in (j) of the Fig. Figure 11 shows a signal that switches S4(34) on from time t2 to time t8, switches S4(34) off from time t8 to time t12 and switches S4(34) on from time t12 to time t17.

[0052] At time t17, the controller 60 switches to a second triangular wave 87, whose phase is further shifted by Δϕ3 (60 degrees). The second triangular wave 87 assumes a trough at time t18 and a crest at time t24. The phase difference of the second triangular wave 87 with respect to the initial second triangular wave 83 or first triangular wave 81 is Δϕ1 (180 degrees). Consequently, as in the case of the waveforms referred to in (a) to (j), the Fig. 7 described operating procedures, PWM1 and PWM2 do not interact with each other at all and / PWM1 and / PWM2 do not interact with each other at all (second control).

[0053] During the time interval from time t17 to time t24, in which the second triangle wave 87 lasts, the control signals SS1 to SS4 for switching S1(31) to S4(34) on or off are calculated using the mathematical equations (5) to (8) described above. SS1 is, as in (g) of the Fig. Figure 11 shows a signal that continuously switches on S1(31). SS2 is, as in (h) the Fig. Figure 11 shows a signal that switches off S2(32) from time t17 to time t20 and switches on S2(32) from time t20 to time t24. SS3 is, as in (i) of the Fig. Figure 11 shows a signal that switches S3(33) on from time t17 to time t20, switches S3(33) off from time t20 to time t22, and switches S3(33) on from time t22 to time t24. Furthermore, SS4 is, as shown in (j) of the Fig. Figure 11 shows a signal that switches S4(34) on from time t17 to time t22 and switches S4(34) off from time t22 to time t24.

[0054] Since SS1 to SS4 are signals from time t0 to time t24 according to the description above, during the initial period of the first triangle wave 81 from time t0 to time t12, S2(32) switches from the on state to the off state or from the off state to the on state at time t4 and time t8, S3(33) switches from the on state to the off state or from the off state to the on state at time t4 and time t12, and S4(34) switches from the on state to the off state or from the off state to the on state at time t8 and time t12. Consequently, in the voltage transformer 10, as indicated by the black triangle markings in (h) and (j) of the Fig. Figure 11 shows a vibration three times at times t4, t8, and t12 during the initial period (from time t0 to time t12) of the first triangular wave 81, and a vibration or electromagnetic noise with a frequency three times higher than the frequency (carrier frequency) of the first triangular wave 81. During the next period of the first triangular wave 81, from time t12 to time t24, S2(32) switches from the on state to the off state or from the off state to the on state at times t16 and t20, S3(33) switches from the on state to the off state or from the off state to the on state at times t16, t20, and t22, and S4(34) switches from the on state to the off state at time t22.Consequently, in the voltage converter 10, a vibration occurs three times at times t16, t20 and t22 during the next period (from time t12 to time t24) of the first triangle wave 81 and a vibration or electromagnetic noise with a frequency that is three times higher than the frequency (carrier frequency) of the first triangle wave 81.

[0055] The second triangle wave 87 continues during the next period (from time t24 to time t36) of the first triangle wave 81 after time t24. Since the second triangle wave 87 is 180 degrees out of phase with the first triangle wave 81, PWM1 and PWM2 do not overlap at all from time t24 to time t36 (second control). PWM2 and PWM2 from time t24 to time t36 exhibit waveforms identical to those from time t0 to time t12 in (d) of the Fig. 7, so that SS1 to SS4 during the next period (from time t24 to time t36) of the first triangular wave 81 after time t24 exhibit waveforms equal to those shown by the solid lines in (g) to (j) of the Fig. 7 are shown. Consequently, in the voltage transformer 10, as with reference to (g) to (j) in the Fig. 7 described, a vibration four times during the next period (from time t24 to time t36) of the first triangle wave 81 and a vibration or electromagnetic noise with a frequency that is four times higher than the frequency (carrier frequency) of the first triangle wave 81.

[0056] In this way, the controller 60 changes the phase difference of the second triangle wave to the first triangle wave 81, or the phase difference of PWM2 to PWM1, in the sequence zero (before time t2, first control), 120 degrees (from time t2 to time t17, first control), and 180 degrees (from time t17, second control) in each period of the first triangle wave 81, according to a predetermined schedule. Consequently, PWM1 and PWM2 change in the sequence (1) the state in which PWM1 and PWM2 overlap (first control), (2) the state in which PWM1 and PWM2 partially overlap (first control), and (3) the state in which PWM1 and PWM2 do not overlap at all (second control).

[0057] If the phase difference is zero, the following steps are performed with reference to (a) to (j) in the Fig. In the basic operating sequences described in Section 6, a vibration occurs twice during one period of the first triangular wave 81 in the voltage transformer 10. During the initial period of the first triangular wave, in which the phase difference is changed to 120 degrees as described above, a vibration occurs three times during one period of the first triangular wave 81. During the next period, in which the phase difference is changed to 180 degrees, a vibration also occurs three times during one period of the first triangular wave 81. During the next period of the first triangular wave 81, in which the phase difference is maintained at 180 degrees, a vibration occurs four times during one period of the first triangular wave 81.Consequently, by changing the phase difference of the second triangle wave relative to the first triangle wave 81 in the sequence zero, 120 degrees, 180 degrees, and 180 degrees in each period of the first triangle wave 81, the frequency of the electromagnetic noise generated by the voltage converter 10 changes in the sequence two, three, three, and four times as high as the frequency of the first triangle wave 81. That is, by changing the phase difference of PWM2 relative to PWM1 in the sequence zero, 120 degrees, 180 degrees, and 180 degrees in each period of PWM1, the frequency of the electromagnetic noise generated by the voltage converter 10 changes in the sequence two, three, three, and four times as high as the frequency of PWM1.If the frequency (carrier frequency) of the first triangle wave 81 is 10 kHz, the frequency of the electromagnetic noise generated by the voltage converter 10 changes in the sequence 20 kHz, 30 kHz, 30 kHz, and 40 kHz. Consequently, the noise frequency band is averaged over a wide range, and the average level of the electromagnetic noise near 20 kHz, which falls within the human hearing range, can be reduced, thus suppressing the noise of the voltage converter 10. The operating sequences can reduce the average number of on / off switching operations of each of S2(32) to S4(34) compared to the case where the phase difference of the second triangle wave 85 with respect to the first triangle wave 81 is set to 180 degrees, equal to those referred to in (a) to (j) in the . Fig. 7 described operating procedures, reduced so that an increase in switching loss can be suppressed and the noise can be reduced, compared to the operating procedures described with reference to (a) to (j) in the Fig. 7 are described, i.e., the operating procedures are those that compensate for an increase in switching loss with a reduction in noise.

[0058] In the above description, the controller 60 changes the phase difference of the second triangle wave with respect to the first triangle wave 81, or the phase difference of PWM2 with respect to PWM1, in the sequence zero (first control), 120 degrees (first control), 180 degrees (second control), and 180 degrees (second control) in each period of the first triangle wave 81 in accordance with a predetermined sequence. Furthermore, the controller 60 changes PWM1 and PWM2 in the sequence (1) the state in which PWM1 and PWM2 overlap (first control), (2) the state in which PWM1 and PWM2 partially overlap (first control), and (3) the state in which PWM1 and PWM2 do not overlap at all (second control), in order to suppress an increase in switching loss and reduce noise.However, as long as it is possible to reduce the average number of on / off switching operations of each of S2(32) to S4(34) compared to the case where the phase difference of the second triangle wave 85 with respect to the first triangle wave 81 is set to 180 degrees, a sequence for changing the phases in each period of the first triangle wave 81 is not limited to the example described above. For example, zero (first control) and 180 degrees (second control) can be switched alternately, i.e., the state in which PWM1 and PWM2 overlap (first control) and the state in which PWM1 and PWM2 do not overlap at all (second control) can be switched alternately, in the sequence zero (first control), 180 degrees (second control), zero (first control), and 180 degrees (second control).Alternatively, the phases of PWM1 and PWM2 can be randomly changed by modifying the phase of the first triangle wave 81 according to a sequence that randomly combines zero, 120 degrees, and 180 degrees. That is, phase control can be achieved by randomly mixing the first control with the second control. In the first control, the phases of the pulse-width modulation control signals are controlled such that the first high-level period of the first pulse-width modulation control signal (PWM1) and the second high-level period of the second pulse-width modulation control signal (PWM2) overlap or partially overlap. In the second control, the phases of the pulse-width modulation control signals are controlled such that the first high-level period of PWM1 and the second high-level period of PWM2 do not overlap.Consequently, the noise frequency band is averaged over a wide range and the average level of electromagnetic noise near 20 kHz, which falls within the human hearing range, can be reduced, so that the noise of the voltage converter 10 can be suppressed.

[0059] Changing PWM2 from low to high level and then resetting PWM2 to low level during the period of low level of PWM1

[0060] The following are the operational sequences for changing PWM2 from the low to the high level and subsequently changing PWM2 back to the low level (changing PWM2 from the high to the low level and subsequently changing PWM2 back to the high level) during a period in which PWM1 is at the low level (during a period in which PWM1 is at the high level), with reference to (a) to (j) in the Fig. 12 described. The following operational procedures are the same as those described with reference to (a) to (j) in the Fig. The 6 are described, in a simplified form.

[0061] The first triangular wave 81 and the straight line 82 (threshold) in (a) of the Fig. 12 are equal to those in (a) of the Fig. 6, and PWM1 and / PWM1 in (b) and (c) of the Fig. 12 are equal to PWM1 and / PWM1, which are defined with reference to (b) and (c) in the Fig. 6 are described. A second triangular wave 89, which PWM2 generates from time t4 to time t8 and from time t16 to time t20, is, as in (d) of the Fig. 12 shown, equal to the second triangle wave 83 from time t4 to time t8 and from time t16 to time t20 in (d) of the Fig. 6. Consequently, PWM1, / PWM1, PWM2, / PWM2 and SS1 to SS4 exhibit signal waves during these time intervals equal to those in (a) to (j) of the Fig. 6. The times of the wave trough positions of the second triangle wave 89 are indicated by the reference symbols t'2, t'9, t'14, t'14, t'21 in the Fig. 12 marked.

[0062] The controller 60 raises the frequency of the second triangle wave 89, as in (d) of the Fig. 12 shown, temporarily beyond the frequency of the first triangle wave 81 such that a period in which the value of the second triangle wave 89 exceeds the straight line 84 (threshold) and a period in which the value of the second triangle wave 89 does not exceed the straight line 84 (threshold) are both present in each of the section from time t0 to time t4, in which PWM1 has the low level ( / PWM1 has the high level), the section from time t8 to time t16 and the section from time t20 to time t24.Consequently, when the value of the second triangle wave 89 exceeds the straight line 84 (threshold), PWM2 exhibits a high level from time t0 to time t1, from time t11 to time t13, and from time t23 to time t24. From time t1 to time t4, from time t8 to time t11, from time t13 to time t16, and from time t20 to time t23, the value of the second triangle wave 89 falls below the straight line 84 (threshold), and PWM2 exhibits a low level. That is, PWM2 transitions from a low to a high level and then returns to a low level, while PWM1 exhibits a low level (from time t8 to time t16).

[0063] The control signals SS1 to SS4 for switching S1(31) to S4(34) on or off in the case that the second triangle wave 89 is used are calculated on the basis of the mathematical equations (5) to (8) described above and are shown in (g) to (j) of the Fig. 12 shown. SS1 and SS2 are signals identical to the signals referred to in (g) and (h) in the Fig. 6 are described. SS3 is a signal that switches off S3(33) at time t1 and switches on S3(33) at time t11, in addition to the signal described with reference to (i) in the Fig. 6 is described. SS4 as the signal that S4(34) in (j) of the Fig. 6 continuously switches on, is a signal that switches S4(34) off from time t0 to time t1, switches S4(34) on from time t1 to time t11, and switches S4(34) off from time t11 to time t13. In this way, in addition to the operations described in (a) to (j) in the Fig. In the operating sequences described in paragraph 6, the number of on / off switching operations of the switching elements during one period (from time t0 to time t12) of the first triangle wave 81 is reduced by two (time t1, time t11), so that it totals four. Consequently, the frequency of the electromagnetic noise generated by the voltage transformer 10 is a frequency four times higher than the frequency of the first triangle wave 81, as in the case described with reference to (a) to (d) in the Fig. 7 described operating procedures. If the frequency of the first triangle wave is 10 kHz, the frequency of the generated electromagnetic noise can be shifted to 40 kHz, which is outside the range of human hearing, so that the noise of the voltage converter 10 can be reduced.

[0064] In the operational sequences, the number of switching operations of each of S1(31) and S2(32) is equal to that of the operations referred to in (a) to (j) in the Fig. The operating procedures described in section 6 allow the noise of the voltage converter 10 to be reduced without increasing the number of switching operations of each of S1(31) and S2(32). Consequently, the noise can also be effectively reduced, for example, even when the temperatures of S1(31) and S2(32) increase and it is difficult to increase the number of switching operations of each of S1(31) and S2(32).

[0065] Each embodiment, as described above, is able to effectively reduce noise by controlling the phases of PWM1 and PWM2 in the power supply system 100, which uses the voltage converter 10, which performs voltage conversion control via the two batteries (B1 (20), B2(23)) using the two pulse width modulation control signals (PWM1, PWM2).

Claims

[1] Energy supply system (100) with: - a first battery (20); - a second battery (23); - a voltage converter (10) with several switching elements (31, 32, 33, 34), wherein the switching elements (31, 32, 33, 34) are designed to bidirectionally convert a voltage between the first battery (20) and / or the second battery (23) and an output line (26) and to switch a connection between the first battery (20) and the second battery (23) to the output line (26) between a series and a parallel connection; and - a controller (60) designed to switch the multiple switching elements (31, 32, 33, 34) on or off in accordance with pulse width modulation control, wherein - the output line (26) has a first electrical line (12) and a second electrical line (11) of lower potential than the first electrical line (12), - the multiple switching elements (31, 32, 33, 34) have a first, second, third and fourth switching element (31, 32, 33, 34) which are connected in series from the first to the second electrical line (12, 11), - the first battery (20) is connected in parallel to the third and fourth switching elements (33, 34), - the second battery (23) is connected in parallel to the second and third switching elements (32, 33), - the controller (60) then, if a total high-level period, which is a total period of a first high-level period and a second high-level period, is shorter than a duty cycle period, is designed to control phases of pulse-width modulation control signals such that the first high-level period and the second high-level period do not overlap, in order to reduce noise by bringing the frequency of the electromagnetic noise of the voltage converter outside the range audible to humans, wherein the first high-level period is a high-level period of a first pulse-width modulation control signal for controlling a first voltage conversion of a first voltage conversion circuit formed between the first battery (20) and the output line (26),the second high-level period is a high-level period of a second pulse-width modulation control signal for controlling a second voltage conversion of a second voltage conversion circuit formed between the second battery (23) and the output line (26), and the duty cycle period is a total period of low-level periods of the pulse-width modulation control signals and a corresponding number of high-level periods of the pulse-width modulation control signals. [2] Energy supply system (100) according to claim 1, characterized by , that the controller (60) is designed, when each of the periods of high level of the pulse width modulation control signals is less than 50% of the duty cycle period, to control the phases of the pulse width modulation control signals such that the periods of high level appear alternately once every half cycle of the duty cycle period. [3] Energy supply system (100) with: - a first battery (20); - a second battery (23); - a voltage converter (10) with several switching elements (31, 32, 33, 34), wherein the switching elements (31, 32, 33, 34) are designed to bidirectionally convert a voltage between the first battery (20) and / or the second battery (23) and an output line (26) and to switch a connection between the first battery (20) and the second battery (23) to the output line (26) between a series and a parallel connection; and - a controller (60) designed to switch the multiple switching elements (31, 32, 33, 34) on or off in accordance with pulse width modulation control, wherein - the output line (26) has a first electrical line (12) and a second electrical line (11) of lower potential than the first electrical line (12), - the multiple switching elements (31, 32, 33, 34) have a first, second, third and fourth switching element (31, 32, 33, 34) which are connected in series from the first to the second electrical line (12, 11), - the first battery (20) is connected in parallel to the third and fourth switching elements (33, 34), - the second battery (23) is connected in parallel to the second and third switching elements (32, 33), - the controller (60) is designed to perform phase control by mixing a first control with a second control if the total high-level period, which is the total period of a first high-level period and a second high-level period, is shorter than a duty cycle period. The first high-level period is a high-level period of a first pulse-width modulation control signal for controlling a first voltage conversion of a first voltage conversion circuit formed between the first battery (20) and the output line (26), and the second high-level period is a high-level period of a second pulse-width modulation control signal for controlling a second voltage conversion of a second voltage conversion circuit formed between the second battery (23) and the output line (26).The duty cycle period is a total period of each of the low-level periods of pulse-width modulation control signals and a corresponding high-level period of the pulse-width modulation control signals, in order to reduce noise by bringing the frequency of the electromagnetic noise of the voltage converter outside the range audible to humans; the first control is a control in which phases of the pulse-width modulation control signals are controlled such that the first high-level period of the first pulse-width modulation control signal and the second high-level period of the second pulse-width modulation control signal overlap; and the second control is a control in which the phases of the pulse-width modulation control signals are controlled such thatthat the first period of high level of the first pulse width modulation control signal and the second period of high level of the second pulse width modulation control signal do not overlap. [4] Energy supply system (100) with: - a first battery (20); - a second battery (23); - a voltage converter (10) with several switching elements (31, 32, 33, 34), wherein the switching elements (31, 32, 33, 34) are designed to bidirectionally convert a voltage between the first battery (20) and / or the second battery (23) and an output line (26) and to switch a connection between the first battery (20) and the second battery (23) to the output line (26) between a series and a parallel connection; and - a controller (60) designed to switch the multiple switching elements (31, 32, 33, 34) on or off in accordance with pulse width modulation control, wherein - the output line (26) has a first electrical line (12) and a second electrical line (11) of lower potential than the first electrical line (12), - the multiple switching elements (31, 32, 33, 34) have a first, second, third and fourth switching element (31, 32, 33, 34) which are connected in series from the first to the second electrical line (12, 11), - the first battery (20) is connected in parallel to the third and fourth switching elements (33, 34), - the second battery (23) is connected in parallel to the second and third switching elements (32, 33), - the controller (60) is designed to, during a period in which a first pulse width modulation control signal for controlling a first voltage conversion of a first voltage conversion circuit formed between the first battery (20) and the output line (26) is at a low level, to raise a second pulse width modulation control signal for controlling a second voltage conversion of a second voltage conversion circuit formed between the second battery (23) and the output line (26) from a low level to a high level and then back to the low level in order to reduce noise by bringing the frequency of the electromagnetic noise of the voltage converter outside the range audible to humans. [5] Energy supply system (100) according to claim 4, characterized by, that the controller (60) is designed to generate the first pulse width modulation control signal based on a first triangle wave and a first threshold, to generate the second pulse width modulation control signal based on a second triangle wave and a second threshold, and to increase a frequency of the second triangle wave above a frequency of the first triangle wave during the period in which the first pulse width modulation control signal is at the low level. [6] Energy supply system (100) according to claim 5, characterized by , that - the controller (60) is designed to increase the frequency of the second triangle wave above the frequency of the first triangle wave during the period in which the first pulse width modulation control signal is at a low level, such that a period in which a value of the second triangle wave exceeds the second threshold and a period in which the value of the second triangle wave does not exceed the second threshold appear.

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