charger

Abstract

This approach minimizes losses in the relays used in chargers while suppressing the need for larger chargers and increased manufacturing costs. [Solution] Charger Ch1 is configured with a first power conversion circuit CNV1 that converts AC power supplied from grid P into DC power and supplies it to battery B, relays Re11 and Re12 connected between grid P and the first power conversion circuit CNV1, and a control circuit CNT that drives relays Re11 and Re12 by PWM control, and the frequencies of the drive signals S11 and S12 for driving relays Re11 and Re12 are different from each other.

Description

Technical Field

[0001] The present invention relates to a charger.

Background Art

[0002] Some chargers include a power conversion circuit that converts AC power supplied from a grid into DC power and supplies the DC power to a battery, and a plurality of cutoff relays connected between the grid and the power conversion circuit. Patent Document 1 is known as related art.

[0003] Incidentally, in order to suppress the loss of each relay, it is conceivable to drive each relay by PWM control.

[0004] However, when each relay is driven by PWM (Pulse Width Modulation) control, the noise intensity corresponding to the multiplication of the frequency of the drive signal of each relay (the peak level of the spectrum at the multiplied frequency of the drive signal of each relay) may exceed the intensity threshold of the EMC (Electromagnetic Compatibility) standard.

[0005] Accordingly, it is conceivable to provide a filter between the charger and the grid in order to suppress noise flowing out from the charger to the grid, but there is a concern that the provision of the filter will increase the size of the charger and raise the manufacturing cost.

[0006] It is also conceivable to set the duty ratio of the drive signal of the relays to 100% to suppress noise flowing out from the charger to the grid, and to provide a fan, a heat dissipation sheet or the like as a thermal measure for the relays, but there is a concern that the provision of the fan, the heat dissipation sheet or the like will increase the size of the charger and raise the manufacturing cost.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

[0008] One aspect of the present invention is to suppress the increase in the size of the charger and the increase in manufacturing costs while minimizing the losses of the relay provided in the charger. [Means for solving the problem]

[0009] One embodiment of the present invention is a charger comprising: a first power conversion circuit that converts AC power supplied from the grid into DC power and supplies it to a battery; first and second relays connected between the grid and the first power conversion circuit; and a control circuit that drives the first and second relays by PWM control, wherein the frequencies of the respective drive signals for driving the first and second relays are different from each other.

[0010] Since the first and second relays are driven by PWM control, losses in the first and second relays can be suppressed. Furthermore, because the frequencies of the drive signals for the first and second relays are different, noise generated when the first and second relays are driven can be suppressed, and noise leaking from the charger to the grid can be suppressed. As a result, there is no need to install a filter on the grid side, which can suppress the increase in the size of the charger and the increase in manufacturing costs. In addition, there is no need to set the duty cycle of the drive signals for the first and second relays to 100% to suppress noise, and there is no need to take thermal countermeasures for the first and second relays, which can suppress the increase in the size of the charger and the increase in manufacturing costs.

[0011] Furthermore, the charger includes third and fourth relays connected between the power system and the first power conversion circuit, and the frequencies of the drive signals for driving the first to fourth relays may be different from each other.

[0012] Furthermore, the charger may include filters connected between the first and second relays and the first power conversion circuit, and between the system and the first and second relays, at least one of the two.

[0013] This makes it possible to further suppress noise that flows out to at least one of the grid side and the first power conversion circuit side.

[0014] Furthermore, the charger includes a second power conversion circuit that converts AC power supplied from the grid into DC power and supplies it to the battery, and fifth and sixth relays connected between the grid and the second power conversion circuit, and the control circuit drives the fifth and sixth relays by PWM control, and the frequencies of the drive signals for driving the fifth and sixth relays, respectively, may be different from each other.

[0015] This allows for a relatively large amount of power to be supplied to the battery, enabling rapid charging. Furthermore, by using different frequencies for the drive signals that operate the fifth and sixth relays, noise generated when the fifth and sixth relays are driven can be suppressed, thus reducing noise leakage from the charger to the grid. This eliminates the need for a filter on the grid side, thus preventing an increase in the size of the charger and manufacturing costs. Additionally, there is no need to set the duty cycle of the drive signals for the fifth and sixth relays to 100% to suppress noise, and there is no need to implement thermal countermeasures for the second relay, thus preventing an increase in the size of the charger and manufacturing costs.

[0016] Furthermore, the charger includes seventh and eighth relays connected between the power system and the second power conversion circuit, and the frequencies of the drive signals for driving the fifth to eighth relays may be different from each other.

[0017] Furthermore, the charger includes third and fourth relays connected between the system and the first power conversion circuit, and seventh and eighth relays connected between the system and the second power conversion circuit, wherein the system is a three-phase four-wire AC power supply, and the frequencies of the drive signals for driving the first to eighth relays are different from each other.

[0018] The charger may also include a first filter connected between the first and second relays and the first power conversion circuit, a second filter connected between the power system and the first and second relays, and a third filter connected between the fifth and sixth relays and the second power conversion circuit.

[0019] This allows the third filter to be disconnected from the first power conversion circuit when the system capacity is relatively small and the first power conversion circuit is operating while the second power conversion circuit is stopped, by switching off the fifth and sixth relays. If the first and second filters are designed for the operation of the first power conversion circuit, the third filter's influence may actually worsen the noise. However, by switching off the fifth and sixth relays, the deterioration of noise due to the influence of the third filter can be suppressed while the first power conversion circuit is operating. [Effects of the Invention]

[0020] According to the present invention, it is possible to suppress the loss of relays in the charger while preventing the charger from becoming larger and the manufacturing cost from increasing. [Brief explanation of the drawing]

[0021] [Figure 1] This figure shows an example of a charger in the first embodiment. [Figure 2] This diagram shows the relationship between the frequency and intensity of noise generated in the charger. [Figure 3] This figure shows an example of the relay and the first power conversion circuit in the first embodiment. [Figure 4] This figure shows another example of a relay circuit in the first embodiment. [Figure 5] This is a diagram showing an example of the charger in the second embodiment. [Figure 6] This is a diagram showing a circuit example of the first power conversion circuit in the second embodiment. [Figure 7] This is a diagram showing an example of the charger in the third embodiment. [Figure 8] This is a diagram showing an example of the charger in the fourth embodiment. [Figure 9] This is a diagram showing an example of the charger in the fifth embodiment. [Modes for Carrying Out the Invention]

[0022] Hereinafter, the embodiments will be described in detail with reference to the drawings.

[0023] <First Embodiment> Figure 1 is a diagram showing an example of the charger in the first embodiment.

[0024] The charger Ch1 shown in Figure 1 is mounted on, for example, a vehicle such as an industrial vehicle or an electric automobile, converts AC power supplied from a power system P (specifically, a charging stand connected to the power system P) into DC power, and supplies the DC power to a battery B mounted on the vehicle. The power system P shown in Figure 1 is assumed to be a single-phase two-wire AC power supply. The battery B is a chargeable and dischargeable battery such as a lithium-ion secondary battery.

[0025] Further, the charger Ch1 includes relays Re11 and Re12, a first power conversion circuit CNV1, and a control circuit CNT. For example, when charging the battery B, the charger Ch1 and the power system P are connected to each other via a charging cable. One of the relays Re11 and Re12 is defined as a first relay, and the other is defined as a second relay.

[0026] Relays Re11 and Re12 are electromagnetic relays (mechanical relays) and are switched between an interrupted state and a conductive state by drive signals S11 and S12 output from the control circuit CNT. When relays Re11 and Re12 are in the interrupted state, the first power conversion circuit CNV1 and the system P are electrically disconnected, and when relays Re11 and Re12 are in the conductive state, the first power conversion circuit CNV1 and the system P are electrically connected.

[0027] When relays Re11 and Re12 are in a conductive state, the first power conversion circuit CNV1 converts the AC power supplied from grid P into DC power and outputs it to battery B, under the operation control of the control circuit CNT. Battery B is charged by the DC power output from charger Ch1. The first power conversion circuit CNV1 may also supply DC power to battery B via a power converter such as a DC-DC converter.

[0028] The control circuit CNT is composed of, for example, a processor or programmable device (such as an FPGA (Field Programmable Gate Array) or a PLD (Programmable Logic Device)) and outputs drive signals S11 and S12, as well as controlling the operation of the first power conversion circuit CNV1.

[0029] For example, after the control circuit CNT determines that charger Ch1 and system P are connected to each other via a charging cable, if an external command to start charging battery B is input, it outputs drive signals S11 and S12 to switch relays Re11 and Re12 from the disconnected state to the conductive state. When it determines that charging of battery B is complete, it outputs drive signals S11 and S12 to switch relays Re11 and Re12 from the conductive state to the disconnected state.

[0030] Furthermore, the control circuit CNT outputs a drive signal S11 to the switch in relay Re11, thereby turning the switch in relay Re11 on and off via PWM control, adjusting the current flowing through the coil in relay Re11, and switching relay Re11 from an off state to a conduction state or from a conduction state to an off state. Also, the control circuit CNT outputs a drive signal S12 to the switch in relay Re12, thereby turning the switch in relay Re12 on and off via PWM control, adjusting the current flowing through the coil in relay Re12, and switching relay Re12 from an off state to a conduction state or from a conduction state to an off state.

[0031] In this configuration, the current flowing through the switches and coils in relays Re11 and Re12 is adjusted by driving the switches within Re11 and Re12 using PWM control. Compared to driving relays Re11 and Re12 without adjusting the current flowing through the switches and coils, the current flowing through the switches and coils in relays Re11 and Re12 can be reduced, thereby suppressing losses in relays Re11 and Re12.

[0032] Figure 2(a) shows the relationship between the frequency and intensity of noise generated in charger Ch1 when the PWM control frequencies of drive signals S11 and S12 are equal (comparative example), and Figure 2(b) shows the relationship between the frequency and intensity of noise generated in charger Ch1 when the PWM control frequencies of drive signals S11 and S12 are different (first embodiment). In the two-dimensional coordinates shown in Figures 2(a) and 2(b), the horizontal axis represents frequency and the vertical axis represents intensity. The solid line in Figure 2(a) shows the relationship between the frequency and intensity of noise generated in charger Ch1 when the frequencies of drive signals S11 and S12 are each f1 [kHz]. The solid line in Figure 2(b) shows the relationship between the frequency and intensity of noise generated in charger Ch1 when the frequency of drive signal S11 is f1 and the frequency of drive signal S12 is f2 [kHz], which is different from f1. Furthermore, the dashed lines shown in Figures 2(a) and 2(b) indicate the intensity thresholds of the EMC standard.

[0033] As shown in Figure 2(a), when the frequencies of drive signals S11 and S12 are f1, the intensity of some of the frequencies that are multiples of f1 among the various frequencies of noise generated in charger Ch1 exceeds the intensity threshold. This is thought to be partly due to the fact that the frequencies of drive signals S11 and S12 are equal to each other, and the intensities corresponding to the multiples of the frequencies of drive signals S11 and S12 are combined to form a relatively large value.

[0034] On the other hand, as shown in Figure 2(b), when the frequencies of the drive signals S11 and S12 are different from each other, the intensity of the noise generated in charger Ch1 corresponding to each frequency is below the intensity threshold. This is thought to be partly due to the fact that the frequencies of the drive signals S11 and S12 are different from each other, causing the frequencies of the frequency multiplication of the drive signals S11 and S12 to spread (disperse) over a relatively wide frequency band, resulting in relatively small intensity values ​​corresponding to the frequencies of the frequency multiplication of the drive signals S11 and S12.

[0035] In other words, in the charger Ch1 of the first embodiment, the frequency f1 of one of the drive signals S11 and S12 for driving relays Re11 and Re12 respectively is made different from the frequency f2 of the other drive signal S12.

[0036] This suppresses the noise generated when relays Re11 and Re12 are driven, thereby suppressing the noise flowing from charger Ch1 to the power grid P side. In this way, since the noise flowing from charger Ch1 to the power grid P side can be suppressed by software modification alone, there is no need to install a filter on the power grid P side, which can prevent the charger Ch1 from becoming larger and the manufacturing costs from increasing. Furthermore, there is no need to set the duty cycle of drive signals S11 and S12 to 100% to reduce losses in relays Re11 and Re12, and there is no need to take thermal countermeasures for relays Re11 and Re12, which can prevent the charger Ch1 from becoming larger and the manufacturing costs from increasing.

[0037] Furthermore, since noise generated when relays Re11 and Re12 are driven can be suppressed, even when filters are installed on the power grid P side or the first power conversion circuit CNV1 side, the flexibility of setting those filters can be improved.

[0038] Figure 3(a) shows an example circuit of relays Re11 and Re12 and the first power conversion circuit CNV1 in the first embodiment.

[0039] Relays Re11 and Re12, shown in Figure 3(a), each comprise a coil CL, a contact CT that becomes conductive or disconnected by the magnetic force generated when a current of a predetermined current Ith or more flows through the coil CL, a regenerative diode D connected in parallel to the coil CL, and a switch SW that adjusts the current flowing through the coil CL by being turned on or off by drive signals S11 and S12.

[0040] Figure 3(b) shows an example of the voltage across the coil CL of relay Re11, and Figure 3(c) shows an example of the current flowing through the coil CL of relay Re11. In the two-dimensional coordinate system shown in Figure 3(b), the horizontal axis represents time and the vertical axis represents voltage. The solid line in Figure 3(b) shows the voltage across the coil CL when the switch SW of relay Re11 is ON or OFF. In the two-dimensional coordinate system shown in Figure 3(c), the horizontal axis represents time and the vertical axis represents current. The solid line in Figure 3(c) shows the current flowing through the coil CL when the switch SW of relay Re11 is ON or OFF. The dashed line in Figure 3(c) represents a predetermined current Ith, which is the minimum current flowing through the coil CL when, for example, the contact CT can maintain its state after switching from an open state to a conduction state or from a conduction state to an open state.

[0041] For example, if relay Re11 is an electromagnetic relay with a normally open contact, when the switch SW of relay Re11 is switched from off to on at time t0 by the drive signal S11, the voltage across the coil CL of relay Re11 rises from 0V to a predetermined voltage Vc, and the current flowing through the coil CL of relay Re11 rises to a predetermined current Ith or higher. Therefore, at time t0, the magnetic force of the coil CL switches the contact CT from the closed state to the conductive state. Subsequently, during the period from time t0 to time t1, when the switch SW of relay Re11 is constantly on by the drive signal S11 with a duty cycle of 100%, the voltage across the coil CL of relay Re11 is maintained at a predetermined voltage Vc, and the current flowing through relay Re11 is maintained to a predetermined current Ith or higher. Therefore, during the period from time t0 to time t1, the magnetic force of the coil CL maintains the contact CT in a conductive state. Subsequently, from time t1 onward, when the switch SW of relay Re11 is repeatedly turned on and off by the drive signal S11 with a duty cycle of 50%, the voltage across coil CL drops from a predetermined voltage Vc to 0V, then rises again to the predetermined voltage Vc, and although the current flowing through coil CL decreases slightly, it is maintained above a predetermined current Ith. Therefore, from time t1 onward, the contact CT is maintained in a conductive state by the magnetic force of coil CL. Similarly, even if relay Re12 is an electromagnetic relay with a normally open contact, the contact CT is maintained in a conductive state by the drive signal S12 with a duty cycle of 100% from time t0 to time t1, and from time t1 onward, the contact CT is maintained in a conductive state by the drive signal S12 with a duty cycle of 50%.

[0042] Furthermore, if relays Re11 and Re12 are electromagnetic relays with normally closed contacts, at time t0, the drive signals S11 and S12 switch the contact CT from a conductive state to a closed state. From time t0 to time t1, the drive signals S11 and S12 with a duty cycle of 100% maintain the contact CT in the closed state. From time t1 onward, the drive signals S11 and S12 with a duty cycle of 50% maintain the contact CT in the closed state.

[0043] Thus, when the switch SW is driven by drive signals S11 and S12 with a duty cycle of 50% after time t1, the current flowing through the switch SW and coil CL after time t1 can be reduced compared to when the switch SW is driven by drive signals S11 and S12 with a duty cycle of 100% after time t1. Therefore, the losses that occur in relays Re11 and Re12 when they are driven can be reduced.

[0044] Furthermore, for example, the control circuit CNT sets the frequency f1 of the drive signal S11 to 20 kHz and the frequency f2 of the drive signal S12 to 21 kHz from time t1 onward.

[0045] Thus, when the frequencies of the drive signals S11 and S12 are differed by 1 kHz after time t1, noise generated in the charger Ch1 can be suppressed compared to when the frequencies of the drive signals S11 and S12 are equal after time t1.

[0046] Furthermore, it is desirable that the frequencies of the drive signals S11 and S12 be pre-set through experiments or simulations so that the losses in the switch SW are not relatively large.

[0047] Furthermore, it is desirable that the difference between the frequency of drive signal S11 and the frequency of drive signal S12 be predetermined through experiments or simulations, taking into account parasitic capacitance and parasitic inductance occurring between the multilayer substrates on which relays Re11 and Re12 are mounted, so that the intensity corresponding to the frequency multiplication of each frequency of drive signals S11 and S12 does not exceed the intensity threshold of the EMC standard.

[0048] Furthermore, the circuit configuration of relays Re11 and Re12 is not limited to the circuit example shown in Figure 3(a), as long as it is possible to control the closed or conducted state by PWM control.

[0049] Furthermore, the first power conversion circuit CNV1 shown in Figure 3(a) comprises an inductor L and switching elements Q11 to Q14. The switching elements Q11 to Q14 are, for example, composed of MOSFETs (Metal Oxide Semiconductor Field-Effect Transistors).

[0050] One terminal of inductor L is connected to one terminal of system P via the contact CT of relay Re11, and the other terminal of inductor L is connected to the connection point between the source terminal of switching element Q11 and the drain terminal of switching element Q12. The connection point between the source terminal of switching element Q13 and the drain terminal of switching element Q14 is connected to the other terminal of system P via the contact CT of relay Re12. The drain terminals of switching elements Q11 and Q13 are connected to one terminal of capacitor C and the positive terminal of battery B, and the source terminals of switching elements Q12 and Q14 are connected to the other terminal of capacitor C and the negative terminal of battery B.

[0051] When charging battery B, if positive AC power is supplied from grid P to the first power conversion circuit CNV1 (when current flows from one terminal of grid P to the connection point of switching elements Q11 and Q12 via the contact CT of relay Re11 and inductor L), the control circuit CNT controls the driving of switching elements Q11 to Q14 so that switching elements Q12 and Q14 turn on and switching elements Q11 and Q13 turn off, and this cycle is repeated. Furthermore, when charging battery B, if negative AC power is supplied from grid P to the first power conversion circuit CNV1 (when current flows from the connection point of switching elements Q11 and Q12 to one terminal of grid P via the inductor L and the contact part CT of relay Re11), the control circuit CNT controls the driving of switching elements Q11 to Q14 so that switching elements Q11 and Q13 turn on and switching elements Q12 and Q14 turn off, and this process is repeated. As a result, the AC power supplied from grid P to the first power conversion circuit CNV1 is rectified. The power rectified by the first power conversion circuit CNV1 is then smoothed by capacitor C and output to battery B.

[0052] Furthermore, the circuit configuration of the first power conversion circuit CNV1 is not limited to the circuit example shown in Figure 3(a), as long as it is capable of converting AC power supplied from the grid P into the desired DC power.

[0053] Figure 4 shows another circuit example of relays Re11 and Re12 in the first embodiment. In Figure 4, components identical to those shown in Figure 3 are denoted by the same reference numerals, and their descriptions are omitted.

[0054] Relay Re11 shown in Figure 4 is a c-contact electromagnetic relay comprising a contact section CT1, a coil CL, a regenerative diode D, and a switch SW. Similarly, relay Re12 is a c-contact electromagnetic relay comprising a contact section CT2, a coil CL, a regenerative diode D, and a switch SW.

[0055] The contact unit CT1 comprises terminal T1, terminal Tp1, and terminal Tc1. Terminal T1 is connected to the connection point of switching elements Q11 and Q12 via an inductor L, terminal Tp1 is connected to one terminal of system P, and terminal Tc1 is connected to one terminal of an outlet CN provided outside the charger Ch1. For example, the outlet CN is provided in the vehicle on which the charger Ch1 is installed.

[0056] The contact unit CT2 includes terminals T2, Tp2, and Tc2. Terminal T2 is connected to the connection point of switching elements Q13 and Q14, terminal Tp2 is connected to the other terminal of system P, and terminal Tc2 is connected to the other terminal of outlet CN.

[0057] For example, consider a case where, when no current greater than a predetermined current Ith flows through coil CL, terminals T1 and Tc1 are electrically connected, terminals T2 and Tc2 are electrically connected, and the first power conversion circuit CNV1 and outlet CN are electrically connected.

[0058] In this case, when the control circuit CNT receives an instruction to supply power to an unillustrated load connected to outlet CN, the control circuit CNT controls the operation of the first power conversion circuit CNV1 so that the DC power supplied from battery B is converted to AC power and supplied to the unillustrated load via relays Re11 and Re12 and outlet CN.

[0059] Furthermore, after the control circuit CNT determines that charger Ch1 and system P are connected to each other via the charging cable, and when a command to start charging battery B is input, it turns the switches SW of relays Re11 and Re12 on and off using PWM control so that a current of Ith or more flows through the coils CL of relays Re11 and Re12. As a result, terminals T1 and Tp1 are electrically connected, and terminals T2 and Tp2 are electrically connected, and the first power conversion circuit CNV1 and system P are electrically connected.

[0060] In charger Ch1 configured in this way, noise generated in charger Ch1 can be suppressed by making the frequencies of the drive signals S11 and S12 for driving relays Re11 and Re12, respectively, different from each other.

[0061] Furthermore, the control circuit CNT may control the operation of the first power conversion circuit CNV1 so that when a power supply instruction to grid P is input, the DC power supplied from battery B is converted to AC power and supplied to grid P via relays Re11 and Re12.

[0062] <Second Embodiment> Figure 5 shows an example of a charger in the second embodiment. In Figure 5, components identical to those shown in Figure 1 are denoted by the same reference numerals, and their descriptions are omitted.

[0063] In charger Ch2 shown in Figure 5, the difference from charger Ch1 shown in Figure 1 is that four relays Re11 to Re14 are connected between the three-phase four-wire AC power system P' (specifically, the charging station connected to system P') and the first power conversion circuit CNV1'. Note that if relays Re11 to Re14 are not distinguished, they will be referred to as relay Re1.

[0064] In the charger Ch2 shown in Figure 5, the frequencies of the drive signals S11 to S14 for driving relays Re11 to Re14 are set to be different from each other. For example, the frequency of drive signal S11 may be 20kHz, the frequency of drive signal S12 21kHz, the frequency of drive signal S13 22kHz, and the frequency of drive signal S14 23kHz. That is, one of the relays Re11 to Re14 may be designated as the first relay, one of the remaining three relays Re1 may be designated as the second relay, one of the remaining two relays Re1 may be designated as the third relay, and the remaining one relay Re1 may be designated as the fourth relay, and the frequencies of the drive signals for driving the first to fourth relays may be set to be different from each other.

[0065] In this way, by making the frequencies of the drive signals S11 to S14 different from each other, noise generated in charger Ch2 can be suppressed.

[0066] Furthermore, among the frequencies of drive signals S11 to S14, the frequencies of drive signals S12 to S14 may be made the same, while the frequency of drive signal S11 may be made different from the frequencies of drive signals S12 to S14. For example, the frequencies of drive signals S12 to S14 may be set to 21 kHz, and the frequency of drive signal S11 may be set to 20 kHz. That is, one of relays Re11 to Re14 may be designated as the first relay, one of the remaining three relays Re1 may be designated as the second relay, and the remaining two relays Re1 may be designated as the third relay, with the frequencies of the drive signals for driving the first and second relays being made different from each other, and the frequency of the drive signal for driving the third relay being the same as the frequency of the drive signal for driving the first relay.

[0067] Alternatively, the frequencies of drive signals S11 and S12 may be made the same as those of drive signals S13 and S14, while the frequencies of drive signals S11 and S12 and drive signals S13 and S14 may be made different. For example, the frequencies of drive signals S11 and S12 may be 20kHz, and the frequencies of drive signals S13 and S14 may be 21kHz. That is, one of the relays Re11 to Re14 may be designated as the first relay, one of the remaining three relays Re1 may be designated as the second relay, one of the remaining two relays Re1 may be designated as the third relay, and the remaining one relay Re1 may be designated as the fourth relay, with the frequencies of the drive signals for driving the first and second relays being different, the frequency of the drive signal for driving the third relay being the same as the frequency of the drive signal for driving the first relay, and the frequency of the drive signal for driving the fourth relay being the same as the frequency of the drive signal for driving the second relay.

[0068] Thus, even if at least one of the frequencies of the drive signals S11 to S14 is different from the other frequencies, noise generated in the charger Ch2 can be suppressed.

[0069] Figure 6 shows an example of the circuit of the first power conversion circuit CNV1' in the second embodiment.

[0070] The first power conversion circuit CNV1' shown in Figure 6 comprises inductors L1 to L3 and switching elements Q21 to Q26. The switching elements Q21 to Q26 are, for example, composed of MOSFETs.

[0071] One terminal of inductor L1 is connected to the R phase of system P' via relay Re11, and the other terminal of inductor L1 is connected to the connection point between the source terminal of switching element Q21 and the drain terminal of switching element Q22. One terminal of inductor L2 is connected to the S phase of system P' via relay Re12, and the other terminal of inductor L2 is connected to the connection point between the source terminal of switching element Q23 and the drain terminal of switching element Q24. One terminal of inductor L3 is connected to the T phase of system P' via relay Re13, and the other terminal of inductor L3 is connected to the connection point between the source terminal of switching element Q25 and the drain terminal of switching element Q26, and is also connected to the neutral point N of system P' via relay Re14. The drain terminals of switching elements Q21, Q23, and Q25 are connected to one terminal of capacitor C and the positive terminal of battery B, and the source terminals of switching elements Q22, Q24, and Q26 are connected to the other terminal of capacitor C and the negative terminal of battery B.

[0072] Note that the circuit examples for relays Re11 to Re14 shown in Figure 6 are the same as, for example, the circuit example for relay Re11 shown in Figure 3.

[0073] For example, after the control circuit CNT determines that charger Ch2 and system P' are connected via a charging cable, and a command to start charging battery B is input, it outputs drive signals S11 to S14 to the respective switches SW of relays Re11 to Re14 so that they switch from the closed state to the conductive state, thereby controlling the operation of the first power conversion circuit CNV1' so that the AC power supplied from each phase of system P' is rectified. Alternatively, after the control circuit CNT determines that charger Ch2 and system P' are connected via a charging cable, and a command to start charging battery B is input, it outputs drive signals S11 to S14 to the respective switches SW of relays Re11 to Re14 so that relays Re11 and Re14 switch from the closed state to the conductive state while relays Re12 and Re13 remain in the closed state, thereby controlling the operation of the first power conversion circuit CNV1' so that the single-phase AC power supplied from the R phase of system P' is rectified. The power rectified by the first power conversion circuit CNV1' is smoothed by capacitor C and supplied to battery B.

[0074] Furthermore, the control circuit CNT may control the operation of the first power conversion circuit CNV1' so that when a power supply instruction to grid P' is received, the DC power supplied from battery B is converted to AC power and supplied to grid P' via relays Re11~Re14.

[0075] Alternatively, relays Re11 and Re14 shown in Figure 6 may be configured as electromagnetic relays with c-contacts, similar to relays Re11 and Re12 shown in Figure 4, and outlet CN may be connected to terminals Tc1 and Tc2 of relays Re11 and Re14. In this case, when a power supply instruction is received from the control circuit CNT for a load (not shown) connected to outlet CN, the control circuit CNT controls the operation of the first power conversion circuit CNV1' so that the DC power supplied from battery B is converted to AC power and supplied to the load (not shown) via relays Re11 and Re14 and outlet CN.

[0076] <Third Embodiment> Figure 7 shows an example of a charger in the third embodiment. In Figure 7, components identical to those shown in Figure 1 are denoted by the same reference numerals, and their descriptions are omitted.

[0077] The charger Ch3 shown in Figure 7 differs from the charger Ch1 shown in Figure 1 in that it further includes a second power conversion circuit CNV2 connected in parallel to the first power conversion circuit CNV1, which converts AC power supplied from the grid P into DC power and supplies it to the battery B, and relays Re21 and Re22 connected between the second power conversion circuit CNV2 and the grid P. One of relays Re21 and Re22 is designated as the fifth relay, and the other as the sixth relay.

[0078] The circuit examples for relays Re11, Re12 and Re21, Re22 shown in Figure 7 are the same as the circuit example for relay Re11 shown in Figure 3. Similarly, the circuit examples for the first power conversion circuit CNV1 and the second power conversion circuit CNV2 shown in Figure 7 are the same as the circuit example for the first power conversion circuit CNV1 shown in Figure 3. Furthermore, relays Re11 and Re12 shown in Figure 7 may be configured as electromagnetic relays with c-contacts, similar to relays Re11 and Re12 shown in Figure 4, and outlets CN may be connected to terminals Tc1 and Tc2 of relays Re11 and Re12. In this case, when a power supply instruction is received from the control circuit CNT for a load (not shown) connected to outlet CN, the control circuit CNT controls the operation of the first power conversion circuit CNV1 so that the DC power supplied from battery B is converted to AC power and supplied to the load (not shown) via relays Re11, Re12 and outlet CN. Furthermore, the control circuit CNT may control the operation of the first power conversion circuit CNV1 so that when a power supply instruction to grid P is input, the DC power supplied from battery B is converted to AC power and supplied to grid P via relays Re11 and Re12.

[0079] In charger Ch3 shown in Figure 7, the frequencies of the drive signal S11 for driving the switch SW of relay Re11 and the drive signal S12 for driving the switch SW of relay Re12 are made different from each other, and the frequencies of the drive signal S21 for driving the switch SW of relay Re21 and the drive signal S22 for driving the switch SW of relay Re22 are also made different from each other. For example, the frequency of drive signal S11 may be 20kHz, the frequency of drive signal S12 may be 21kHz, the frequency of drive signal S21 may be 22kHz, and the frequency of drive signal S22 may be 23kHz. That is, one of relays Re11 and Re12 may be designated as the first relay and the other as the second relay, one of relays Re21 and Re22 may be designated as the fifth relay and the other as the sixth relay, and the frequencies of the drive signals for driving the first, second, fifth, and sixth relays may be made different from each other.

[0080] Alternatively, the frequencies of drive signals S11 and S21 may be set to 20 kHz, and the frequencies of drive signals S12 and S22 may be set to 21 kHz. That is, one of relays Re11 and Re12 may be designated as the first relay and the other as the second relay, one of relays Re21 and Re22 may be designated as the fifth relay and the other as the sixth relay, and the frequencies of the drive signals for driving the first and second relays may be made different from each other, as well as the frequencies of the drive signals for driving the fifth and sixth relays may be made different from each other.

[0081] Thus, in the charger Ch3 of the third embodiment, the frequencies of the drive signals S11 and S12 and the frequencies of the drive signals S21 and S22 are made different from each other, so that noise generated in the charger Ch3 can be suppressed.

[0082] Furthermore, in the third embodiment, the charger Ch3 is configured to include a second power conversion circuit CNV2 in addition to the first power conversion circuit CNV1, which allows for a relatively large amount of power to be supplied to the battery B, enabling rapid charging of the battery B.

[0083] <Fourth Embodiment> Figure 8(a) shows an example of a charger in the fourth embodiment, Figure 8(b) shows another example of a charger in the fourth embodiment, and Figure 8(c) shows an example of a filter circuit. In Figures 8(a) and 8(b), the same reference numerals are used for the same components as in Figure 1, and their descriptions are omitted.

[0084] In charger Ch4 shown in Figure 8(a), the difference from charger Ch1 shown in Figure 1 is that a filter FLT is connected between relays Re11 and Re12 and the first power conversion circuit CNV1. For example, the filter FLT is composed of capacitor Cx as an X capacitor and capacitors Cy1 and Cy2 as Y capacitors, as shown in Figure 8(c). Note that the circuit configuration of the filter FLT is not limited to the circuit example shown in Figure 8(c), as long as it is possible to reduce the noise generated from relays Re11 and Re12.

[0085] Furthermore, in charger Ch4' shown in Figure 8(b), the difference from charger Ch1 shown in Figure 1 is that a filter FLT is connected between the power system P and relays Re11 and Re12. In addition, in charger Ch4' shown in Figure 8(b), a filter FLT may be further connected between relays Re11 and Re12 and the first power conversion circuit CNV1.

[0086] The circuit configurations of relays Re11 and Re12 shown in Figures 8(a) and 8(b) are the same as the circuit example of relay Re11 shown in Figure 3. Similarly, the circuit configuration of the first power conversion circuit CNV1 shown in Figures 8(a) and 8(b) is the same as the circuit example of the first power conversion circuit CNV1 shown in Figure 3. Furthermore, relays Re11 and Re12 shown in Figures 8(a) and 8(b) may be configured as electromagnetic relays with c-contacts, similar to relays Re11 and Re12 shown in Figure 4, and outlets CN may be connected to terminals Tc1 and Tc2 of relays Re11 and Re12. In this case, when a power supply instruction to an unshown load connected to outlet CN is input, the control circuit CNT controls the operation of the first power conversion circuit CNV1 so that the DC power supplied from battery B is converted to AC power and supplied to the unshown load via relays Re11, Re12 and outlet CN. Furthermore, the control circuit CNT may control the operation of the first power conversion circuit CNV1 so that when a power supply instruction to grid P is input, the DC power supplied from battery B is converted to AC power and supplied to grid P via relays Re11 and Re12.

[0087] In charger Ch4 shown in Figure 8(a) and charger Ch4' shown in Figure 8(b), the frequencies of the drive signals S11 and S12 for driving relays Re11 and Re12, respectively, are set to be different from those of charger Ch1 shown in Figure 1.

[0088] Thus, in the fourth embodiment, the frequencies of the drive signals S11 and S12 are made different in charger Ch4 or charger Ch4', which suppresses the intensity of noise generated in charger Ch4 or charger Ch4', and suppresses noise flowing from relays Re11 and Re12 to the grid P and the first power conversion circuit CNV1.

[0089] Furthermore, in the charger Ch4 of the fourth embodiment, a filter FLT is connected between relays Re11 and Re12 and the first power conversion circuit CNV1, which further suppresses noise flowing from relays Re11 and Re12 to the first power conversion circuit CNV1.

[0090] Furthermore, in the charger Ch4' of the fourth embodiment, a filter FLT is connected between the grid P and relays Re11 and Re12, which further suppresses noise flowing from relays Re11 and Re12 to the grid P.

[0091] <Fifth Embodiment> Figure 9 shows an example of a charger in the fifth embodiment. In Figure 9, the same reference numerals are used for the same components as in Figure 5, and their descriptions are omitted.

[0092] The charger Ch5 shown in Figure 9 differs from the charger Ch2 shown in Figure 5 in that it includes a second power conversion circuit CNV2' which is connected in parallel to the first power conversion circuit CNV1' and converts AC power supplied from the grid P' into DC power for supply to the battery B; relays Re21 to Re24 connected between the second power conversion circuit CNV2' and the grid P'; filter FLT1 (first filter) connected between relays Re11 to Re14 and the first power conversion circuit CNV1'; filter FLT2 (second filter) connected between the grid P' and relays Re11 to Re14; and filter FLT3 (third filter) connected between relays Re21 to Re24 and the second power conversion circuit CNV2'. Note that relays Re21 to Re24 are referred to as relay Re2 when not distinguished.

[0093] The circuit configurations of relays Re11-Re14 and Re21-Re24 shown in Figure 9 are the same as the circuit example of relay Re11 shown in Figure 3. Furthermore, the circuit configurations of the first power conversion circuit CNV1' and the second power conversion circuit CNV2' shown in Figure 9 are the same as the circuit example of the first power conversion circuit CNV1' shown in Figure 6. Additionally, relays Re11 and Re14 shown in Figure 9 may be configured as electromagnetic relays with c-contacts, similar to relays Re11 and Re12 shown in Figure 4, and outlets CN may be connected to terminals Tc1 and Tc2 of relays Re11 and Re14. In this case, when a power supply instruction to an unshown load connected to outlet CN is input, the control circuit CNT controls the operation of the first power conversion circuit CNV1' so that the DC power supplied from battery B is converted to AC power and supplied to the unshown load via relays Re11, Re14 and outlet CN. Furthermore, the control circuit CNT may control the operation of the first power conversion circuit CNV1' so that when a power supply instruction to grid P' is input, the DC power supplied from battery B is converted to AC power and supplied to grid P' via relays Re11~Re14.

[0094] In charger Ch5 shown in Figure 9, similar to charger Ch2 shown in Figure 5, the frequencies of the drive signals S11 to S14 for driving relays Re11 to Re14 and the frequencies of the drive signals S21 to S24 for driving relays Re21 to Re24 are made different from each other. For example, the frequency of drive signal S11 is set to 20kHz, the frequency of drive signal S12 to 21kHz, the frequency of drive signal S13 to 22kHz, the frequency of drive signal S14 to 23kHz, the frequency of drive signal S21 to 24kHz, the frequency of drive signal S22 to 25kHz, the frequency of drive signal S23 to 26kHz, and the frequency of drive signal S24 to 27kHz. That is, one of the relays Re11 to Re14 is designated as the first relay, one of the remaining three relays Re1 is designated as the second relay, one of the remaining two relays Re1 is designated as the third relay, and the remaining relay Re1 is designated as the fourth relay. Furthermore, one of the relays Re21 to Re24 is designated as the 5th relay, one of the remaining three Re2 relays is designated as the 6th relay, one of the remaining two Re2 relays is designated as the 7th relay, and the remaining Re2 relay is designated as the 8th relay. The frequencies of the drive signals for each of the 1st to 8th relays are made to be different from each other.

[0095] Alternatively, the frequencies of drive signals S11 and S21 may be set to 20kHz, drive signals S12 and S22 to 21kHz, drive signals S13 and S23 to 22kHz, and drive signals S14 and S24 to 23kHz. That is, one of relays Re11 to Re14 may be designated as the first relay, one of the remaining three relays Re1 may be designated as the second relay, one of the remaining two relays Re1 may be designated as the third relay, and the remaining one relay Re1 may be designated as the fourth relay. Furthermore, one of relays Re21 to Re24 may be designated as the fifth relay, one of the remaining three relays Re2 may be designated as the sixth relay, one of the remaining two relays Re2 may be designated as the seventh relay, and the remaining one relay Re2 may be designated as the eighth relay. The frequencies of the drive signals for driving the first to fourth relays may be made different from each other, and the frequencies of the drive signals for driving the fifth to eighth relays may also be made different from each other.

[0096] Alternatively, one of relays Re11 to Re14 may be designated as the first relay, one of the remaining three relays Re1 as the second relay, and the remaining two Re1 relays as the third relay. Also, one of relays Re21 to Re24 may be designated as the fifth relay, one of the remaining three Re2 relays as the sixth relay, and the remaining two Re2 relays as the seventh relay. Furthermore, the frequencies of the drive signals for driving the first and second relays may be made different from each other, the frequency of the drive signal for driving the third relay may be made the same as the frequency of the drive signal for driving the first relay, the frequencies of the drive signals for driving the fifth and sixth relays may be made different from each other, and the frequency of the drive signal for driving the seventh relay may be made the same as the frequency of the drive signal for driving the fifth relay.

[0097] Alternatively, one of relays Re11 to Re14 can be designated as the 1st relay, one of the remaining three Re1 relays as the 2nd relay, one of the remaining two Re1 relays as the 3rd relay, and the remaining one Re1 relay as the 4th relay. Furthermore, one of relays Re21 to Re24 can be designated as the 5th relay, one of the remaining three Re2 relays as the 6th relay, one of the remaining two Re2 relays as the 7th relay, and the remaining one Re2 relay as the 8th relay. Furthermore, the frequencies of the drive signals for driving the first and second relays may be made different from each other, the frequency of the drive signal for driving the third relay may be made the same as the frequency of the drive signal for driving the first relay, the frequency of the drive signal for driving the fourth relay may be made the same as the frequency of the drive signal for driving the second relay, the frequencies of the drive signals for driving the fifth and sixth relays may be made different from each other, the frequency of the drive signal for driving the seventh relay may be made the same as the frequency of the drive signal for driving the fifth relay, and the frequency of the drive signal for driving the eighth relay may be made the same as the frequency of the drive signal for driving the sixth relay.

[0098] Thus, in the charger Ch5 of the fifth embodiment, at least one of the frequencies of the drive signals S11 to S14 and the frequencies of the drive signals S21 to S24 is made different from the other frequencies, so that noise generated in the charger Ch5 can be suppressed.

[0099] Furthermore, in the charger Ch5 of the fifth embodiment, since filter FLT1 is connected between relays Re11~Re14 and the first power conversion circuit CNV1', noise flowing from relays Re11~Re14 to the first power conversion circuit CNV1' can be further suppressed. Also, since filter FLT2 is connected between system P' and relays Re11~Re14, noise flowing from relays Re11~Re14 to system P' can be further suppressed. Also, since filter FLT3 is connected between relays Re21~Re24 and the second power conversion circuit CNV2', noise flowing from relays Re21~Re24 to the second power conversion circuit CNV2' can be further suppressed.

[0100] Furthermore, in the fifth embodiment, charger Ch5 is configured to include a second power conversion circuit CNV2' in addition to the first power conversion circuit CNV1', which allows for a relatively large amount of power to be supplied to battery B, enabling rapid charging of battery B. Also, if the capacity of the charging station is small, the first power conversion circuit CNV1' may be operated and the second power conversion circuit CNV2' may be stopped. In this case, the filter FLT3 can be disconnected by putting relays Re21~Re24 into a disconnected state. Since filters FLT1 and FLT2 are designed for the operation of the first power conversion circuit CNV1', there is a risk that the noise will worsen if filter FLT3 is involved. However, by putting relays Re21~24 into a disconnected state, the deterioration of noise due to the influence of filter FLT3 while the first power conversion circuit CNV1' is operating can be suppressed.

[0101] It should be noted that the present invention is not limited to the embodiments described above, and various improvements and modifications are possible without departing from the spirit of the invention.

[0102] For example, filter FLT1 shown in Figure 9 may be connected between relays Re11 and Re12 shown in Figure 7 and the first power conversion circuit CNV1; filter FLT2 shown in Figure 9 may be connected between system P shown in Figure 7 and relays Re11 and Re12; and filter FLT3 shown in Figure 9 may be connected between relays Re21 and Re22 shown in Figure 7 and the second power conversion circuit CNV2.

[0103] As a result, when the capacity of system P is relatively small and the first power conversion circuit CNV1 is operated while the second power conversion circuit CNV2 is stopped, the filter FLT3 can be disconnected from the first power conversion circuit CNV1 by switching off relays Re21 and Re22. If filters FLT1 and FLT2 are designed for the operation of the first power conversion circuit CNV1, the noise may worsen if filter FLT3 is involved. However, by switching off relays Re21 and Re22, the deterioration of noise due to the influence of filter FLT3 during the operation of the first power conversion circuit CNV1 can be suppressed. [Explanation of Symbols]

[0104] Ch1~Ch5 Charger Re11~Re14 Relay Re21~Re26 Relay CNV1, CNV1' First Power Conversion Circuit CNV2, CNV2' Second Power Conversion Circuit CNT control circuit P, P´ lineage B Battery CT contact part CL Coil D Regenerative diode SW Switch L, L1~L3 Inductors Q11-Q14, Q21-Q26 Switching elements C Capacitor FLT, FLT1~FLT3 filters

Claims

1. A first power conversion circuit that converts AC power supplied from the grid into DC power and supplies it to the battery, First and second relays connected between the aforementioned system and the first power conversion circuit, A control circuit that drives the first and second relays by PWM control, Equipped with, The frequencies of the drive signals for driving the first and second relays, respectively, are different from each other. charger.

2. A charger according to claim 1, The system includes third and fourth relays connected between the system and the first power conversion circuit, The frequencies of the drive signals for driving the first to fourth relays are different from each other. charger.

3. A charger according to claim 1, The system includes filters connected between the first and second relays and the first power conversion circuit, and at least one of the filters connected between the system and the first and second relays. charger.

4. A charger according to claim 1, A second power conversion circuit that converts AC power supplied from the aforementioned system into DC power and supplies it to the battery, Fifth and sixth relays connected between the aforementioned system and the second power conversion circuit, Equipped with, The control circuit drives the fifth and sixth relays by PWM control, The frequencies of the drive signals for driving the fifth and sixth relays, respectively, are different from each other. charger.

5. A charger according to claim 4, The system includes seventh and eighth relays connected between the aforementioned system and the second power conversion circuit, The frequencies of the drive signals for driving the fifth to eighth relays are different from each other. charger.

6. A charger according to claim 4, Third and fourth relays connected between the aforementioned system and the first power conversion circuit, Seventh and eighth relays connected between the aforementioned system and the second power conversion circuit, Equipped with, The aforementioned system is a three-phase four-wire AC power supply. The frequencies of the drive signals for driving the first to eighth relays are different from each other. charger.

7. A charger according to claim 4, A first filter connected between the first and second relays and the first power conversion circuit, A second filter connected between the aforementioned system and the first and second relays, A third filter connected between the fifth and sixth relays and the second power conversion circuit, A charger equipped with the following features.

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