Drive power supply for mechanical switch and power supply device

Abstract

A mechanical switch according to the present invention includes a mechanical contact and coils (42, 44) that are supplied a drive current to open and close the mechanical contact. A drive power supply according to the present invention comprises capacitors (C1, C2) and switches (SW1, SW2) that are connected between the capacitors (C1, C2) and the coils (42, 44). To turn the mechanical switch on or off, the switches (SW1, SW2) are temporarily turned on to supply the drive current from the capacitors (C1, C2) to the coils (42, 44). The drive power supply also comprises a charging circuit (36) that charges the capacitors (C1, C2) to a reference voltage when the switches (SW1, SW2) are off and a control device (23) that controls the switches (SW1, SW2) and the charging circuit (36). To keep a peak value for the drive current within a normal range, the control device (23) calculates an appropriate voltage range for the capacitors on the basis of a circuit parameter for a resonance circuit through which the drive current flows. The control device (23) generates the reference voltage on the basis of the appropriate voltage range calculated for the capacitors.

Description

Drive Power Supply for Mechanical Switch and Power Supply Device

[0001] The present disclosure relates to a drive power supply for a mechanical switch and a power supply device.

[0002] Japanese Unexamined Patent Application Publication No. 2008-92746 (Patent Document 1) discloses a capacitor charging device. This capacitor charging device includes a rapid charging circuit of a DC chopper type or an LC resonance type, and a fine adjustment charging circuit that charges a capacitor to a charging voltage command value by constant current charging after rapid charging. The voltage control circuit of the rapid charging circuit is configured to correct changes in the rapid charging voltage due to capacitance variations of the capacitor or reactor value variations of the reactor included in the rapid charging circuit.

[0003] Japanese Unexamined Patent Application Publication No. 2008-92746

[0004] The drive power supply that supplies a drive current to the mechanical switch is equipped with a capacitor that stores DC power, and is configured to turn on or off the mechanical switch using the power stored in the capacitor. Specifically, the mechanical switch includes a mechanical contact and a coil that receives the supply of the drive current and opens and closes the mechanical contact. The drive power supply is configured to supply a drive current from the capacitor to the coil by temporarily turning on a switch connected between the capacitor and the coil.

[0005] Note that after turning on or off the mechanical switch, the drive power supply supplies a charging current from a charging circuit to the capacitor to charge the capacitor so that the capacitor stores power for driving the mechanical switch next time.

[0006] To ensure the proper operation of such mechanical switches, a normal range is defined for the peak value of the drive current supplied to the coil. However, the circuit through which the drive current flows from the capacitor to the coil includes the capacitance and parasitic resistance of the coil and capacitor, as well as the resistance and inductance of the wiring. Therefore, differences in these circuit parameters can cause differences in the peak value of the drive current. Furthermore, the capacitance and parasitic resistance of the capacitor can change depending on the state of the capacitor. Consequently, if the charging voltage of the capacitor is controlled to a constant value by the charging circuit, the drive current may deviate from the normal range when the mechanical switch is driven, potentially causing the mechanical switch to fail to switch. Moreover, a drive current exceeding the normal range may damage the mechanical switch.

[0007] This disclosure has been made in view of the above-mentioned problems, and the purpose of this disclosure is to provide a drive power supply that can stably and normally operate a mechanical switch.

[0008] A drive power supply according to one aspect of the present disclosure supplies a drive current to a mechanical switch. The mechanical switch includes a mechanical contact and a coil that receives the drive current to open and close the mechanical contact. The drive power supply comprises a capacitor and a switch connected between the capacitor and the coil. The switch is configured to supply a drive current from the capacitor to the coil by being temporarily turned on to turn the mechanical switch on or off. The drive power supply comprises a charging circuit that charges the capacitor to a reference voltage during the off period of the switch, and a control device that controls the switch and the charging circuit. The control device calculates an appropriate voltage range for the capacitor to keep the peak value of the drive current within a predetermined normal range, based on the circuit parameters of the resonant circuit through which the drive current flows. The control device generates a reference voltage based on the calculated appropriate voltage range for the capacitor.

[0009] According to this disclosure, the peak value of the drive current flowing through the coil of the mechanical switch can always be kept within the normal range. As a result, the mechanical switch can be operated stably and normally.

[0010] This figure shows the configuration of a power supply device to which the drive power supply for the mechanical switch according to this embodiment is applied. This figure shows an example of the hardware configuration of the control device. This figure shows an example of the configuration of the drive power supply. This is a circuit diagram showing an example of the circuit configuration of the drive power supply. This is a diagram for explaining the operation of the drive power supply. This figure shows a circuit through which the drive current flows. This is a block diagram showing the configuration of the reference voltage generation unit. This is a block diagram showing the configuration of the calculation unit. This is a diagram for explaining an example of the measurement process of the capacitance of a capacitor in the measurement unit. This is a block diagram showing the configuration of the calculation unit.

[0011] Embodiments of this disclosure will be described in detail below with reference to the drawings. In the following, the same or corresponding parts in the drawings will be denoted by the same reference numerals, and their descriptions will not be repeated in principle.

[0012] <Power Supply Configuration> Figure 1 shows the configuration of a power supply to which the drive power supply for the mechanical switch according to this embodiment is applied. In Figure 1, a voltage sag compensation device is described as an example of a power supply.

[0013] As shown in Figure 1, the voltage drop compensation device comprises an input terminal T1, an output terminal T2, a DC terminal T3, VCBs (Vacuum Circuit Breakers) 1, 5, 6, 21, a high-speed switch 2, a power converter 7, a transformer 20, an operating unit 22, a control device 23, and a drive power supply 30.

[0014] The input terminal T1 receives a commercial frequency AC voltage VI supplied from the commercial AC power supply 110. The instantaneous value of the AC voltage VI is detected by the control device 23. The control device 23 determines that an instantaneous voltage drop (instantaneous slack) has occurred when the AC voltage VI falls below a lower limit.

[0015] The output terminal T2 is connected to the load 112. The load 112 is driven by the AC voltage VO supplied from the output terminal T2. The instantaneous value of the AC voltage VO is detected by the control device 23.

[0016] The DC terminal T3 is connected to the power storage device 113. The power storage device 113 stores DC power. The power storage device 113 may be a battery or a capacitor. The DC voltage VDC at the DC terminal T3 is detected by the control device 23.

[0017] VCB1, high-speed switch2, and VCB5 are connected in series between input terminal T1 and output terminal T2. VCB1 and VCB5 are turned on during normal operation of the voltage sag compensation device and turned off, for example, during maintenance of high-speed switch2 or when bypass power is supplied.

[0018] The high-speed switch 2 includes a semiconductor switch 3 and a mechanical switch 4 connected in series. The semiconductor switch 3 is controlled by the control device 23 and is turned on when the AC voltage VI is normal and turned off when the AC voltage VI is abnormal (during a momentary dip).

[0019] The mechanical switch 4 is driven by the drive power supply 30. The drive power supply 30 is controlled by the control device 23, which drives the mechanical switch 4 to the ON state when the AC voltage VI is normal, and drives the mechanical switch 4 to the OFF state when the AC voltage VI is abnormal (during a momentary dip).

[0020] The semiconductor switch 3 has the characteristics of faster operating speed and lower voltage resistance compared to the mechanical switch 4. The mechanical switch 4 has the characteristics of slower operating speed and higher voltage resistance compared to the semiconductor switch 3. By connecting the semiconductor switch 3 and the mechanical switch 4 in series, a high-speed switch 2 is constructed that turns on instantaneously when a voltage sag occurs and has high voltage resistance.

[0021] VCB6 is connected between input terminal T1 and output terminal T2. VCB6 is turned off during normal operation of the voltage sag compensation device and turned on, for example, during bypass power supply. When VCB6 is turned on, an AC voltage VI is supplied from the commercial AC power supply 110 to the load 112 via VCB6, and the load 112 is driven.

[0022] The power converter 7 includes a bidirectional converter 8, a fuse 9, a current detector 10, a reactor 11, and a capacitor 12. The DC terminal 8a of the bidirectional converter 8 is connected to the DC terminal T3, and its AC terminal 8b is connected to the primary winding 20a of the transformer 20 via the fuse 9 and the reactor 11. The secondary winding 20b of the transformer 20 is connected to node N1 between the high-speed switch 2 and the VCB 5 via the VCB 21. The instantaneous value of the AC voltage VAC appearing on the primary winding 20a of the transformer 20 is detected by the control device 23.

[0023] The bidirectional converter 8 is a well-known type comprising multiple semiconductor switching elements and multiple diodes, and is controlled by the control device 23, for example, using PWM (Pulse Width Modulation). By turning each semiconductor switching element in the bidirectional converter 8 on and off at a predetermined frequency, it is possible to convert AC power to DC power, or conversely, DC power to AC power.

[0024] If the AC voltage VI supplied from the commercial AC power supply 110 is normal, the bidirectional converter 8 converts the AC power supplied from the commercial AC power supply 110 via the VCB1, high-speed switch 2, VCB21, transformer 20, reactor 11, and fuse 9 into DC power and stores it in the power storage device 113.

[0025] Furthermore, if the AC voltage VI is not normal, the bidirectional converter 8 converts the DC power of the power storage device 113 into AC power and outputs it to the AC terminal 8b. This AC power is supplied to the load 112 via the fuse 9, reactor 11, transformer 20, and VCBs 21 and 5.

[0026] The fuse 9 protects the bidirectional converter 8 from overcurrent. The current detector 10 detects the current IL flowing through the reactor 11 and provides the control device 23 with a signal ILf indicating the detected value.

[0027] The reactor 11 and capacitor 12 constitute an AC filter. The AC filter is a low-pass filter that allows commercial frequency current to pass through while blocking the switching frequency current generated by the bidirectional converter 8. In other words, the AC filter converts the output power of the bidirectional converter 8 into a sinusoidal AC voltage VAC.

[0028] The transformer 20 exchanges AC power between node N1 and the power converter 7. The VCB 21 is turned on during normal operation of the voltage sag compensation device and turned off, for example, during maintenance of the high-speed switch 2 or the power converter 7.

[0029] The control unit 22 includes multiple buttons, multiple switches, and a display. By operating the control unit 22, the user of the voltage sag compensation device can instruct the device to start, stop, operate automatically and manually, and set various conditions. The control unit 22 provides signals to the control device 23 indicating the user's instructions.

[0030] The control device 23 controls the entire voltage sag compensation system based on signals from the operation unit 22, AC voltages VI, VO, VAC, DC voltage VDC, output signal ILf from the current detector 10, etc.

[0031] If the AC voltage VI supplied from the commercial AC power supply 110 is normal, the control device 23 turns on the high-speed switch 2 and controls the bidirectional converter 8 based on the AC voltage VAC, the DC voltage VDC, and the output signal ILf from the current detector 10 so that the DC voltage VDC at the DC terminal T3 becomes a predetermined reference DC voltage VDCr.

[0032] If the AC voltage VI supplied from the commercial AC power supply 110 is not normal (during a momentary dip), the control device 23 turns off the high-speed switch 2 and controls the bidirectional converter 8 so that the AC voltage VO at the output terminal T2 becomes a predetermined reference AC voltage VOr.

[0033] Figure 2 shows an example of the hardware configuration of the control device 23. Typically, the control device 23 can be configured with a microcomputer that has a predetermined program pre-stored in it. For example, as shown in Figure 2, the control device 23 is configured to include a CPU (Central Processing Unit) 230, a memory 232, and an input / output (I / O) circuit 234. The CPU 230, memory 232, and I / O circuit 234 can exchange data with each other via a bus 236. A program is pre-stored in a part of the memory 232, and various functions can be realized by the CPU 230 executing this program.

[0034] Alternatively, unlike the example in Figure 2, at least a portion of the control device 23 can be configured using circuits such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). Furthermore, at least a portion of the control device 23 can also be configured using analog circuits.

[0035] Returning to Figure 1, the drive power supply 30 is controlled by the control device 23 and drives the mechanical switch 4. The drive power supply 30 is equipped with a capacitor that stores DC power, and uses the power stored in the capacitor to turn on the mechanical switch 4 when the AC voltage VI is normal, and to turn off the mechanical switch 4 when the AC voltage VI is abnormal (during a momentary dip).

[0036] <Configuration of the drive power supply> Figure 3 is a diagram showing an example of the configuration of the drive power supply 30 according to this embodiment. As shown in Figure 3, the drive power supply 30 is configured to supply drive current to the mechanical switch 4.

[0037] The mechanical switch 4 includes a mechanical contact 40 and coils 42 and 44 that open and close the mechanical contact 40. The mechanical contact 40 is formed using an elastic material such as a spring.

[0038] The coil 42 receives a drive current Ion from the drive power supply 30 and closes the mechanical contact 40 by converting electrical energy into mechanical energy. When the mechanical contact 40 is closed, the mechanical switch 4 is turned on, and the mechanical switch 4 is energized (turned on). In the following description, the coil 42 will also be referred to as the "turn-on coil" for turning on the mechanical switch 4.

[0039] The coil 44 receives a drive current Ioff from the drive power supply 30 and converts electrical energy into mechanical energy, thereby opening the mechanical contact 40. When the mechanical contact 40 is opened, the mechanical switch 4 is turned off, and the current to the mechanical switch 4 is stopped (opened). In the following explanation, the coil 44 will also be referred to as the "opening coil" for turning off the mechanical switch 4.

[0040] The power supply 30 includes drive circuits 32 and 34 and a charging circuit 36. The drive circuits 32 and 34 and the charging circuit 36 ​​are controlled by the control device 23.

[0041] The drive circuit 32 is a circuit for supplying a drive current Ion to the closing coil 42. The drive circuit 34 is a circuit for supplying a drive current Ioff to the open coil 44. Each of the drive circuits 32 and 34 includes a capacitor that stores DC power, and is configured to supply a drive current to the corresponding coil using the DC power of the capacitor.

[0042] The charging circuit 36 ​​is a circuit for charging the capacitors included in each of the drive circuits 32 and 34. Each of the drive circuits 32 and 34 supplies a drive current to its corresponding coil, which reduces the amount of charge stored in the capacitor and lowers the voltage across the capacitor terminals (hereinafter simply referred to as "capacitor voltage"). The charging circuit 36 ​​charges the capacitor by supplying a charging current Ichg to the capacitor whose voltage has dropped.

[0043] FIG. 4 is a circuit diagram showing a circuit configuration example of the drive power supply 30 shown in FIG. 3. As shown in FIG. 4, the drive circuit 32 includes a positive input terminal 32a, a negative input terminal 32b, a positive output terminal 32c, a negative output terminal 32d, a capacitor C1, a diode D1, a switch SW1, a voltage detector 320, a current detector 322, and a temperature detector 324.

[0044] The positive input terminal 32a is connected to the DC positive bus bar PL1, and the negative input terminal 32b is connected to the DC negative bus bar NL1. An input coil 42 is connected between the positive output terminal 32c and the negative output terminal 32d. The input coil 42 can be represented by a series circuit of an inductance Lcoil_on and a DC resistance Rcoil_on of the coil.

[0045] The capacitor C1 is connected between the DC positive bus bar PL1 and the DC negative bus bar NL1. The capacitor C1 is configured, for example, by connecting a plurality of electrolytic capacitor elements in series and / or in parallel. The capacitor C1 can be represented by a series circuit of a capacitance C_on and an ESR (Equivalent Series Resistance) ESR_on which is a resistance component. Note that an electrolytic capacitor has a characteristic that its capacitance decreases as deterioration progresses. Also, an electrolytic capacitor has a characteristic that its ESR decreases as the ambient temperature rises.

[0046] The voltage detector 320 detects the voltage Von of the capacitor C1 and gives a signal Vonf indicating the detected value to the control device 23. The temperature detector 324 detects the ambient temperature Ton of the capacitor C1 and gives a signal Tonf indicating the detected value to the control device 23.

[0047] The diode D1 is connected between the positive input terminal 32a and the positive terminal of the capacitor C1. The diode D1 is a diode for preventing reverse current.

[0048] Switch SW1 is a switch for controlling the supply and stop of the drive current Ion. The on and off states of switch SW1 are controlled by the control device 23. When switch SW1 is turned on, the drive current Ion is supplied from capacitor C1 to the input coil 42. Switch SW1 corresponds to an embodiment of the "first switch". The current detector 322 detects the drive current Ion and gives a signal Ionf indicating the detected value to the control device 23. The path through which the drive current Ion flows includes the wiring resistance Ro_on and the wiring inductance Lo_on as parasitic components.

[0049] The drive circuit 34 has the same configuration as the drive circuit 32. Specifically, the drive circuit 34 includes a positive input terminal 34a, a negative input terminal 34b, a positive output terminal 34c, a negative output terminal 34d, a capacitor C2, a diode D2, a switch SW2, a voltage detector 340, a current detector 342, and a temperature detector 344.

[0050] The positive input terminal 34a is connected to the DC positive bus PL2, and the negative input terminal 34b is connected to the DC negative bus NL2. The DC positive bus PL2 is electrically connected to the DC positive bus PL1. The DC negative bus NL2 is electrically connected to the DC negative bus NL1.

[0051] An open coil 44 is connected between the positive output terminal 34c and the negative output terminal 34d. The open coil 44 can be represented by a series circuit of an inductance Lcoil_off and a DC resistance Rcoil_off of the coil.

[0052] The capacitor C2 is connected between the DC positive bus PL2 and the DC negative bus NL2. The capacitor C2 is formed, for example, by connecting a plurality of electrolytic capacitor elements in series and / or in parallel. The capacitor C2 can be represented by a series circuit of a capacitance C_off and an ESR_off.

[0053] The voltage detector 340 detects the voltage Voff of the capacitor C2 and gives a signal Vofff indicating the detected value to the control device 23. The temperature detector 344 detects the ambient temperature Toff of the capacitor C2 and gives a signal Tofff indicating the detected value to the control device 23.

[0054] Diode D2 is connected between the positive input terminal 34a and the positive terminal of capacitor C2. Diode D2 is a diode for preventing reverse current.

[0055] Switch SW2 is a switch for controlling the supply and cessation of the drive current Ioff. The on and off of switch SW2 is controlled by the control device 23. When switch SW2 is turned on, the drive current Ioff is supplied from capacitor C2 to the open coil 44. Switch SW2 corresponds to one embodiment of the "second switch". The current detector 342 detects the drive current Ioff and provides the control device 23 with a signal Ioff indicating the detected value. The path through which the drive current Ioff flows includes, as parasitic components, wiring resistance Ro_off and wiring inductance Ro_off.

[0056] The charging circuit 36 ​​includes a battery 36a and a DC / DC converter 36b. The DC / DC converter 36b is controlled by the control device 23 and generates a charging current Ichg based on the DC power of the battery 36a. The DC / DC converter 36b outputs an output voltage that matches the lower of the two voltages, Von and Voff. Since the drive circuits 32 and 34 are each provided with diodes D1 and D2 for preventing reverse current, the charging current Ichg is supplied only to the capacitor with the lower voltage. When the voltages Von and Voff are equal, the charging current Ichg is supplied to capacitors C1 and C2. In this case, the charging current supplied to each capacitor is approximately half the charging current supplied to a single capacitor.

[0057] When the voltages Von and Voff rise and reach the target value, the reference voltage Vref, the control device 23 stops supplying the charging current Ichg by stopping the operation of the DC / DC converter 36b.

[0058] The drive power supply 30 further includes a current detector 38. The current detector 38 detects the charging current Ichg and provides the control device 23 with a signal Ichgf indicating the detected value.

[0059] The control device 23 includes a command generation unit 50, an on-off control unit 52, an off-off control unit 54, a charge control unit 56, and a reference voltage generation unit 58. These functional blocks are typically realized by the CPU 230 shown in Figure 2 executing a program pre-stored in the memory 232.

[0060] The command generation unit 50 generates an on command to turn on the mechanical switch 4 and an open command to turn off the mechanical switch 4 based on the AC voltage VI at the input terminal T1. Specifically, the command generation unit 50 activates the on command to the H (logical high) level when the AC voltage VI supplied from the commercial AC power supply 110 is normal. When the AC voltage VI supplied from the commercial AC power supply 110 falls below the lower limit and a momentary dip occurs, the command generation unit 50 activates the open command to the H level.

[0061] Each of the closing command and the opening command is a signal that is activated to the H level for a predetermined period. The H level period for the closing command can be set based on the electrical energy required by the closing coil 42 to close the mechanical contact 40. The H level period for the opening command can be set based on the electrical energy required by the opening coil 44 to open the mechanical contact 40.

[0062] The command generation unit 50 further generates charge commands for charging capacitors C1 and C2. Specifically, the command generation unit 50 activates the charge command to the H level when the ON command is deactivated from the H level to the L level, or when the OFF command is deactivated from the H level to the L level. Then, the command generation unit 50 deactivates the charge command to the L level when the voltages V1 and V2 reach the reference voltage Vref due to the charging of capacitors C1 and / or capacitor C2.

[0063] The closing control unit 52 controls the on and off of switch SW1 in the drive circuit 32 according to the closing command provided by the command generation unit 50. Specifically, the closing control unit 52 turns on switch SW1 during the period when the closing command is at the H level. During the ON period of switch SW1, a drive current Ion is supplied from the drive circuit 32 to the closing coil 42. The closing coil 42 closes the mechanical contact 40 by converting the electrical energy based on the drive current Ion into mechanical energy. The closing of the mechanical contact 40 turns on the mechanical switch 4. When the closing command is deactivated from the H level to the L level, the closing control unit 52 stops supplying the drive current Ion from the drive circuit 32 to the closing coil 42 by turning off switch SW1.

[0064] The open control unit 54 controls the on and off of switch SW2 in the drive circuit 34 according to the open command provided by the command generation unit 50. Specifically, the open control unit 54 turns on switch SW2 during the period when the open command is at the H level. During the ON period of switch SW2, a drive current Ioff is supplied from the drive circuit 34 to the open coil 44. The open coil 44 opens the mechanical contact 40 by converting the electrical energy based on the drive current Ioff into mechanical energy. The mechanical switch 4 is turned off when the mechanical contact 40 is opened. When the open command is deactivated from the H level to the L level, the open control unit 54 stops supplying the drive current Ioff from the drive circuit 34 to the open coil 44 by turning off switch SW2.

[0065] The charge control unit 56 controls the DC / DC converter 36b in the charge circuit 36 ​​according to the charge command provided by the command generation unit 50. Specifically, when the charge command is activated to the H level, the charge control unit 56 starts the DC / DC converter 36b and begins charging capacitors C1 and C2. The DC / DC converter 36b supplies a charging current Ichg to capacitors C1 and C2. As charge accumulates in capacitors C1 and C2, the voltages Von and Voff gradually increase. When the voltages Von and Voff reach the reference voltage Vref, the charge control unit 56 stops the operation of the DC / DC converter 36b and stops supplying the charging current Ichg.

[0066] The reference voltage generation unit 58 generates a reference voltage Vref, which is the target value for the voltages of capacitors C1 and C2. Specifically, the reference voltage generation unit 58 generates the reference voltage Vref based on signals from a plurality of detectors provided in the drive power supply 30, such that the drive current Ion supplied to coil 42 and the drive current Ioff supplied to coil 44 fall within a predetermined normal range. The method for generating the reference voltage Vref will be explained in detail later.

[0067] <Operation of the drive power supply> Figure 5 is a diagram illustrating the operation of the drive power supply 30. Figure 5 shows waveforms representing the time changes of switches SW1 and SW2, drive currents Ion and Ioff, capacitor voltages Von and Voff across C1 and C2, and charging current Ichg.

[0068] As shown in Figure 5, if a momentary dip in the commercial AC power supply 110 occurs at time t1, the open control unit 54 temporarily turns on switch SW2 in accordance with the open command from the command generation unit 50. In Figure 5, switch SW2 is in the ON state for the period from time t1 to t2.

[0069] During the ON period of switch SW2, a drive current Ioff is supplied from the drive circuit 34 to the open coil 44. The drive current Ioff rises from 0 after time t1. The open coil 44 converts the electrical energy based on the drive current Ioff into mechanical energy, thereby opening the mechanical contact 40. This turns off the mechanical switch 4.

[0070] Before time t1, the voltage Voff across capacitor C2 is maintained at the reference voltage Vref. The voltage Voff across capacitor C2 is proportional to the amount of charge stored in capacitor C2. During the period from time t1 to t2, the amount of charge stored in capacitor C2 decreases due to the supply of the drive current Ioff, so the voltage Voff across capacitor C2 decreases. In response to the switch SW2 being turned off at time t2, the charge control unit 56 controls the DC / DC converter 36b to charge capacitor C2 according to the charge command from the command generation unit 50.

[0071] The DC / DC converter 36b outputs a voltage matching the lower of the two voltages, Von and Voff, thereby supplying a charging current Ichg to the capacitor C2. As a result, charge accumulates in the capacitor C2 from time t2 onward, and the voltage Voff gradually increases. Since the charging current Ichg is a constant current (current value I1), the voltage Voff increases linearly.

[0072] If the commercial AC power supply 110 is restored at time t3, the power-on control unit 52 temporarily turns on switch SW1 in accordance with the power-on command from the command generation unit 50. In Figure 5, switch SW1 is in the ON state for the period from time t3 to t4.

[0073] During the ON period of switch SW1, a drive current Ion is supplied from the drive circuit 32 to the closing coil 42. The drive current Ion rises from 0 after time t3. The closing coil 42 closes the mechanical contact 40 by converting the electrical energy based on the drive current Ion into mechanical energy. This turns on the mechanical switch 4.

[0074] Before time t3, the voltage Von across capacitor C1 is maintained at the reference voltage Vref. The voltage Von across capacitor C1 is proportional to the amount of charge stored in capacitor C1. During the period from time t3 to t4, the amount of charge stored in capacitor C1 decreases due to the supply of the drive current Ion, so the voltage Von across capacitor C1 decreases. In response to the switch SW1 being turned off at time t4, the charge control unit 56 controls the DC / DC converter 36b to charge capacitor C1.

[0075] In the example shown in Figure 5, at time t4, since neither voltage Von nor Voff has reached the reference voltage Vref, the charge control unit 56 controls the DC / DC converter 36b to charge capacitors C1 and C2. Specifically, the DC / DC converter 36b outputs an output voltage that matches the lower of the two voltages, Von and Voff. Since voltage Von is lower than voltage Voff, from time t4 onward, the charging current Ichg is supplied only to capacitor C1. As a result, charge accumulates in capacitor C1, and voltage Von increases linearly. On the other hand, from time t4 onward, the supply of charging current Ichg to capacitor C2 is stopped, so voltage Voff maintains its value at time t4.

[0076] When the voltage Von increases and becomes equal to the voltage Voff (time t5), the DC / DC converter 36b supplies a charging current Ichg to capacitors C1 and C2. From time t5 onward, the voltages Von and Voff gradually increase as charge accumulates in capacitors C1 and C2. When the voltages Von and Voff reach the reference voltage Vref, the charging control unit 56 stops supplying the charging current Ichg by stopping the operation of the DC / DC converter 36b.

[0077] As explained above, the drive power supply 30 turns the mechanical switch 4 on or off by supplying drive currents Ion and Ioff from capacitors C1 and C2 to coils 42 and 44, respectively, to open and close the mechanical contact 40. After turning the mechanical switch 4 on or off, the drive power supply 30 charges capacitors C1 and C2 by supplying a charging current Ichg from the charging circuit 36 ​​to capacitors C1 and C2 so that they store power to drive the mechanical switch 4 the next time.

[0078] Here, we will explain the peak values ​​of the drive currents Ion and Ioff shown in Figure 5. Since the basic concepts of the peak value of the drive current Ion, Ion_peak, and the peak value of the drive current Ioff, Ioff_peak, are the same, we will explain Ion_peak as a representative example.

[0079] The circuit through which the drive current Ion flows from the drive circuit 32 to the closing coil 42 is a resonant circuit including the capacitance C of capacitor C1, resistance R, and inductance L, as shown in Figure 6. In this resonant circuit, capacitance C is the capacitance C_on of capacitor C1. Resistance R is the sum of the ESR_on of capacitor C1, the wiring resistance Ro_on, and the DC resistance Rcoil_on of the closing coil 42. Inductance L is the sum of the wiring inductance Lo_on and the inductance Lcoil_on of the closing coil 42.

[0080] The driving current Ion flowing through this resonant circuit is given by the following equation (1).

[0081]

[0082] However, V is the voltage across capacitor C1. α and γ are expressed by equations (2) and (3), respectively.

[0083]

[0084]

[0085] The timing t (peak) at which the drive current Ion reaches its peak value can be obtained from the first derivative of equation (1) as shown in equation (4).

[0086]

[0087] The peak value of the drive current Ion, Ion_peak, is given by equation (5) from equations (1) and (4).

[0088]

[0089] Thus, the peak value of the drive current Ion, Ion_peak, corresponds to the peak value of the current flowing through the resonant circuit, which includes the capacitance C, resistance R, and inductance L of capacitor C1. As shown in equation (5), the peak value Ion_peak is a function of the capacitance C, inductance L, and resistance R included in the resonant circuit and the voltage V across capacitor C1. Of these, capacitance C, inductance L, and resistance R have individual differences due to component variations, etc. Therefore, even if the voltage V across capacitor C1 is the same value, differences in the circuit parameters of the resonant circuit may result in differences in the peak value Ion_peak.

[0090] Furthermore, capacitance C decreases as capacitor C1 deteriorates. In addition, the ESR_on of capacitor C1 included in resistor R may change depending on the ambient temperature. Therefore, when the voltage V across capacitor C1 is constant, the peak value Ion_peak may change according to the deterioration state of capacitor C1 and the ambient temperature of capacitor C1.

[0091] Similarly, the peak value of the drive current Ioff, Ioff_peak, depends on the circuit parameters of the resonant circuit, including the capacitance C, resistance R, and inductance L of capacitor C2. Furthermore, when the voltage across capacitor C2 is constant, the peak value Ioff_peak may change depending on the degradation state of capacitor C2 and the ambient temperature of capacitor C2.

[0092] On the other hand, in order for the mechanical switch 4 to operate correctly, the peak values ​​of the drive currents Ion and Ioff are each defined as normal ranges. If the peak values ​​of the drive currents Ion and Ioff fall below the normal range, the mechanical contacts 40 cannot be opened or closed, and as a result, the switching operation of the mechanical switch 4 may fail. In addition, if the drive currents Ion and Ioff flow above the normal range, the mechanical contacts 40, coils 42 and 44, etc. may be damaged.

[0093] To address these concerns, in this embodiment, the reference voltage Vref, which is the target value of the voltage across capacitors C1 and C2, is generated based on the circuit parameters of the resonant circuit so that the peak values ​​of the drive currents Ion and Ioff always remain within the normal range. Furthermore, the capacitance and ESR of capacitors C1 and C2, which are among the circuit parameters, are set to variable values ​​according to the degradation state of capacitors C1 and C2 and the ambient temperature. The generation process of the reference voltage Vref in the reference voltage generation unit 58 will be described in detail below.

[0094] <Configuration of the Reference Voltage Generation Unit> Figure 7 is a block diagram showing the configuration of the reference voltage generation unit 58 shown in Figure 4. As shown in Figure 7, the reference voltage generation unit 58 is composed of calculation circuits 60, 80, calculation unit 98, abnormality detection units 70, 90, and voltage / current detection units 100, 102.

[0095] The arithmetic circuit 60 is a circuit for calculating the appropriate voltage range of capacitor C1. The appropriate voltage range of capacitor C1 is defined by an upper limit value Von_max and a lower limit value Von_min. The arithmetic circuit 60 includes arithmetic units 61, 68, 72, 74, and 76, an adder 62, and a multiplier 64.

[0096] In this specification, the coefficient K1 is a coefficient (first coefficient) for converting the peak value Ion_peak of the drive current Ion into the voltage across capacitor C1. As shown in equation (6) below, the voltage V across capacitor C1 is expressed as the product of the peak value Ion_peak of the drive current Ion and the coefficient K1.

[0097]

[0098] Here, the peak value Ipeak in equation (5) can be transformed into a function of the voltage V across capacitor C1, as shown in equation (7).

[0099]

[0100] From equation (7), the coefficient K1 is given by the following equation (8).

[0101]

[0102] The calculation unit 61 calculates the coefficient K1 based on the output signal Tonf of the temperature detector 324, the output signal Vonf of the voltage detector 320, the output signal Ichgf of the current detector 38, and the circuit parameters of the circuit (resonant circuit) through which the drive current Ion flows. The coefficient Kin1 output from the calculation unit 61 corresponds to the calculated value of the coefficient K1.

[0103] The circuit parameters of the resonant circuit include the wiring resistance Ro_on and wiring inductance Lo_on of the drive circuit 32, the inductance Lcoil_on and DC resistance Rcoil_on of the switching coil 42, and the capacitance C_on of the capacitor C1. These circuit parameters can be used as initial values ​​based on the values ​​listed in the characteristic tables or circuit design documents for each component.

[0104] Figure 8 is a block diagram showing the configuration of the arithmetic unit 61 shown in Figure 7. As shown in Figure 8, the arithmetic unit 61 includes arithmetic units 602, 614, and 616, adders 604, 606, 608, and 610, and a measurement unit 612.

[0105] The calculation unit 602 calculates the ESR of capacitor C1 based on the ambient temperature Ton of capacitor C1 detected by the temperature sensor 324. Specifically, the calculation unit 602 pre-stores the temperature-dependent characteristics of the ESR of capacitor C1 as characteristic data. By referring to this characteristic data, the calculation unit 602 calculates the ESR of capacitor C1 based on the ambient temperature Ton.

[0106] The adder 606 adds the wiring resistance Ro_on of the drive circuit 32 and the DC resistance Rcoil_on of the closing coil 42. The adder 604 adds the sum of the resistors R1total included in the circuit through which the drive current Ion flows (resonant circuit) by adding the sum of the adder 606 and the ESR of capacitor C1 calculated by the calculation unit 602.

[0107] The adder 608 calculates the total inductance L1total included in the circuit through which the drive current Ion flows (resonant circuit) by adding the wiring inductance Lo_on of the drive circuit 32 and the inductance Lcoil_on of the closing coil 42.

[0108] The adder 610 corrects the capacitance C_on of capacitor C1 to C1 by adding a correction value ΔC1 to it. In the calculation unit 61, the initial value of capacitance C_on, which is listed in the characteristic table of capacitor C1, is used. As a result, a discrepancy occurs between the capacitance C_on and the actual value depending on the usage time of capacitor C1. The correction value ΔC1 is used to compensate for such a discrepancy and is generated using the measured capacitance of capacitor C1.

[0109] Specifically, the measurement unit 612 measures the capacitance of capacitor C1 while it is being charged, based on the voltage Von of capacitor C1 detected by the voltage detector 320 and the charging current Ichg detected by the current detector 38.

[0110] Figure 9 is a diagram illustrating an example of the capacitance measurement process of capacitor C1 in the measurement unit 612. Figure 9 shows extracted portions of the waveforms of the voltage Von and charging current Ichg of capacitor C1 shown in Figure 5. The capacitance measurement process will be explained using Figure 9.

[0111] As shown in Figure 9, before time t4, the voltage Von across capacitor C1 decreases with the supply of the drive current Ion. At time t4, the charging circuit 36 ​​starts supplying a charging current Ichg to capacitor C1. From time t4 onward, the charging circuit 36 ​​is controlled by the charging control unit 56 and supplies a charging current Ichg with a constant value I1 to capacitor C1.

[0112] The voltage Von across capacitor C1 rises by ΔV2 at time t4 when the supply of the charging current Ichg begins. This change in ΔV2 is caused by a change in the current flowing through ESR_on in capacitor C1.

[0113] During the period from time t4 to t5, the voltage Von increases linearly. The measurement unit 612 detects the value VA of the voltage Von at time ta, which is after time t4, based on the output signal Vonf of the voltage detector 320. Time ta corresponds to the start of measurement. VA corresponds to the voltage Von of capacitor C1 at the start of measurement (hereinafter also referred to as the "measurement start voltage"). The time difference between time t2 and time ta is several milliseconds, and is set so as not to include fluctuations in the voltage Von caused by ESR_on in the measurement results.

[0114] The measurement unit 612 adds a predetermined amount ΔV1 to VA and sets the sum VB as the voltage Von of capacitor C1 at the end of the measurement (hereinafter also referred to as the "end measurement voltage") (VB = VA + ΔV1). The predetermined amount ΔV1 is set to, for example, a magnitude of about 1 / 2 to 1 / 3 of the rated voltage of capacitor C1. This is to avoid including the voltage Von fluctuations caused by ESR_on when the supply of charging current Ichg is stopped in the measurement results.

[0115] The measurement unit 612 detects the time tb at which the voltage Von reaches the measurement termination voltage VB, based on the output signal Vonf of the voltage detector 320. This time tb corresponds to the end of the measurement.

[0116] Next, the measurement unit 612 detects the charging current Ichg during the measurement period from the start time ta to the end time tb, based on the output signal Ichgf of the current detector 38. Then, the measurement unit 612 calculates the amount of charge Q accumulated in the capacitor C1 during the measurement period by integrating the charging current Ichg during the measurement period. In the example in Figure 9, since the charging current Ichg is a constant value I1, the amount of charge Q is Q = I1 × (tb - ta). The amount of charge Q corresponds to the area of ​​the waveform of the charging current Ichg enclosed by time ta and time tb.

[0117] The measurement unit 612 determines the capacitance C of capacitor C1 by dividing the calculated charge amount Q by the change in voltage Von during the measurement period (a predetermined amount ΔV1) (C = Q / ΔV1).

[0118] Returning to Figure 8, the calculation unit 614 calculates the deviation Cerr between the capacitance C (measured value) provided by the measurement unit 612 and the capacitance C1 output from the adder 610 (Cerr = C1 - C). Then, the calculation unit 616 calculates a correction value ΔC1 by performing a control calculation to reduce the deviation Cerr. For example, the calculation unit 614 calculates a proportional control amount Kp1・Cerr based on the deviation Cerr. Kp1 is the proportional gain. The correction value ΔC1 is added to the capacitance C_on in the adder 610.

[0119] The calculation unit 618 calculates the coefficient K1 using R1total, L1total, C1, and equations (2), (3), and (8). The calculation unit 618 outputs the coefficient Kin1, which is the calculated value of coefficient K1.

[0120] The calculation unit 72 calculates the actual value of coefficient K1 based on the output signal Vonf from the voltage detector 320 and the peak value Ion_peak of the drive current Ion, which is obtained from the output signal Ionf from the current detector 322. Specifically, the calculation unit 72 calculates the coefficient K1 by substituting the detected voltage Von and peak value Ion_peak from the voltage detector 320 into equation (6). The calculation unit 72 outputs the coefficient Kout1, which is the actual value of coefficient K1.

[0121] The calculation unit 74 calculates the deviation Kerr between the coefficient Kin1 (calculated value) given by the calculation unit 61 and the coefficient Kout1 (actual value) given by the calculation unit 72 (Kerr = Kin1 - Kout1). Then, the calculation unit 74 calculates a correction amount ΔK1 by performing a control calculation to reduce the deviation Kerr. For example, the calculation unit 74 calculates a proportional control amount Kp2・Kerr based on the deviation Kerr. Kp2 is the proportional gain.

[0122] The adder 62 corrects the coefficient Kin1 (calculated value) provided by the arithmetic unit 61 to the coefficient K1 by adding a correction amount ΔK1. By correcting the coefficient Kin1 in this way to reduce the deviation Kerr between the coefficient Kout1 (actual value) and the coefficient Kin1 (calculated value), the coefficient K1 can be determined, thereby reducing the deviation of the coefficient K1 due to individual differences in circuit parameters, etc.

[0123] Returning to Figure 7, the multiplier 64 calculates the appropriate voltage range for capacitor C1 based on the coefficient K1 provided by the adder 62 and the normal range of the drive current Ion. Specifically, the normal range of the drive current Ion is defined by an upper limit Ion_max and a lower limit Ion_min. The multiplier 64 calculates the upper limit Von_max of the appropriate voltage range by substituting the coefficient K1 and the upper limit Ion_max into equation (6). The multiplier 64 also calculates the lower limit Von_min of the appropriate voltage range by substituting the coefficient K1 and the lower limit Ion_min into equation (6).

[0124] The arithmetic circuit 80 is a circuit for calculating the appropriate voltage range of capacitor C2. The appropriate voltage range of capacitor C2 is defined by an upper limit value Voff_max and a lower limit value Voff_min. The arithmetic circuit 80 has the same circuit configuration as the arithmetic circuit 60. Specifically, the arithmetic circuit 80 includes arithmetic units 81, 88, 92, 94, and 96, an adder 82, and a multiplier 84.

[0125] In this specification, coefficient K2 is a coefficient (second coefficient) for converting the peak value Ioff_peak of the drive current Ioff into the voltage across capacitor C2. As shown in equation (9) below, the voltage V across capacitor C2 is expressed as the product of the peak value Ioff_peak of the drive current Ioff and coefficient K1.

[0126]

[0127] Similar to coefficient K1, coefficient K2 is given by the following equation (10).

[0128]

[0129] The calculation unit 81 calculates the coefficient K2 based on the output signal Toff of the temperature detector 344, the output signal Voff of the voltage detector 340, the output signal Ichgf of the current detector 38, and the circuit parameters of the circuit (resonant circuit) through which the drive current Ioff flows. The coefficient Kin2 output from the calculation unit 81 corresponds to the calculated value of the coefficient K2.

[0130] The circuit parameters of the resonant circuit include the wiring resistance Ro_off and wiring inductance Lo_off of the drive circuit 34, the inductance Lcoil_off and DC resistance Rcoil_off of the open coil 44, and the capacitance C_off of the capacitor C2. These circuit parameters can be used as initial values ​​based on the values ​​listed in the characteristic tables or circuit design documents for each component.

[0131] Figure 10 is a block diagram showing the configuration of the arithmetic unit 81 shown in Figure 7. As shown in Figure 10, the arithmetic unit 81 includes arithmetic units 802, 814, and 816, adders 804, 806, 808, and 810, and a measurement unit 812.

[0132] The calculation unit 802 calculates the ESR of capacitor C2 based on the ambient temperature Toff detected by the temperature sensor 344. Specifically, the calculation unit 802 pre-stores the temperature-dependent characteristics of the ESR of capacitor C2 as characteristic data. By referring to this characteristic data, the calculation unit 802 calculates the ESR of capacitor C2 based on the ambient temperature Toff.

[0133] The adder 806 adds the wiring resistance Ro_off of the drive circuit 34 and the DC resistance Rcoil_off of the open coil 44. The adder 804 adds the sum of the additions from the adder 806 and the ESR of the capacitor C2 calculated by the calculation unit 802 to calculate the total value of the resistances R2total included in the circuit through which the drive current Ioff flows (resonant circuit).

[0134] The adder 808 calculates the total inductance L2total included in the circuit through which the drive current Ion flows (resonant circuit) by adding the wiring inductance Lo_off of the drive circuit 34 and the inductance Lcoil_on of the open coil 442.

[0135] The adder 810 corrects the capacitance C_off of capacitor C2 to C2 by adding a correction value ΔC2 to it. In the calculation unit 81, the initial value of capacitance C_off, which is listed in the characteristic table of capacitor C2, is used. As a result, a discrepancy occurs between capacitance C_off and the actual value depending on the usage time of capacitor C2. The correction value ΔC2 is used to compensate for such a discrepancy and is generated using the measured capacitance of capacitor C2.

[0136] The measurement unit 812 measures the capacitance of capacitor C2 based on the voltage Voff of capacitor C2 detected by the voltage detector 340 and the charging current Ichg detected by the current detector 38 while capacitor C2 is being charged. The measurement process for the capacitance of capacitor C2 in the measurement unit 812 is the same as the measurement process for the capacitance of capacitor C1 in the measurement unit 612 described in Figure 9.

[0137] The calculation unit 814 calculates the deviation Cerr between the capacitance C (measured value) provided by the measurement unit 812 and the capacitance C2 output from the adder 810 (Cerr = C2 - C). Then, the calculation unit 816 calculates a correction value ΔC2 by performing a control calculation to reduce the deviation Cerr. For example, the calculation unit 814 calculates a proportional control amount Kp1・Cerr based on the deviation Cerr. Kp1 is the proportional gain. The correction value ΔC2 is added to the capacitance C_off in the adder 810.

[0138] The calculation unit 818 calculates the coefficient K2 using R2total, L2total, C2, and equations (2), (3), and (10). The calculation unit 818 outputs the coefficient Kin2, which is the calculated value of coefficient K2.

[0139] The calculation unit 92 calculates the actual value of the coefficient K2 based on the output signal Voff from the voltage detector 340 and the peak value Ioff_peak of the drive current Ioff, which is obtained from the output signal Ioff from the current detector 342. Specifically, the calculation unit 92 calculates the coefficient K2 by substituting the detected value of the voltage Voff and the detected value of the peak value Ioff_peak from the voltage detector 340 into equation (9). The calculation unit 92 outputs the coefficient Kout2, which is the actual value of the coefficient K2.

[0140] The calculation unit 94 calculates the deviation Kerr between the coefficient Kin2 (calculated value) given by the calculation unit 81 and the coefficient Kout2 (actual value) given by the calculation unit 92 (Kerr = Kin2 - Kout2). Then, the calculation unit 94 calculates a correction amount ΔK2 by performing a control calculation to reduce the deviation Kerr. For example, the calculation unit 94 calculates a proportional control amount Kp2・Kerr based on the deviation Kerr, where Kp2 is the proportional gain.

[0141] The adder 82 corrects the coefficient Kin2 (calculated value) provided by the arithmetic unit 81 to the coefficient K2 by adding a correction amount ΔK2. By correcting the coefficient Kin2 in this way to reduce the deviation Kerr between the coefficient Kout2 (actual value) and the coefficient Kin2 (calculated value), the coefficient K2 can be determined, thereby reducing the deviation of the coefficient K2 due to individual differences in circuit parameters, etc.

[0142] Returning to Figure 7, the multiplier 84 calculates the appropriate voltage range for capacitor C2 based on the coefficient K2 provided by the adder 82 and the normal range of the drive current Ioff. Specifically, the normal range of the drive current Ioff is defined by an upper limit Ioff_max and a lower limit Ioff_min. The multiplier 84 calculates the upper limit Voff_max of the appropriate voltage range by substituting the coefficient K2 and the upper limit Ioff_max into equation (9). The multiplier 84 also calculates the lower limit Voff_min of the appropriate voltage range by substituting the coefficient K2 and the lower limit Ioff_min into equation (9).

[0143] The calculation unit 98 calculates a reference voltage Vref based on the appropriate voltage range of capacitor C1 calculated by the calculation unit 68 and the appropriate voltage range of capacitor C2 calculated by the calculation unit 88. Specifically, the calculation unit 98 identifies the range in which the appropriate voltage ranges of capacitor C1 and capacitor C2 overlap. Then, the calculation unit 98 determines the reference voltage Vref within the identified range. For example, the calculation unit 98 obtains the reference voltage Vref by averaging the upper and lower limits of the identified range. The calculation unit 98 outputs the generated reference voltage Vref to the charge control unit 56.

[0144] The voltage / current detection unit 100 acquires the output signal Ichgf from the current detector 38 and the output signals Vonf and Vofff from the voltage detectors 320 and 340 while capacitors C1 and C2 are charging, and provides the acquired signals to the calculation units 61 and 81. The calculation units 61 and 81 each use the acquired signals to calculate the capacitance of capacitors C1 and C2, as described above.

[0145] The voltage / current detection unit 102 acquires the output signals Ionf and Ioff from the current detectors 322 and 342, and the output signals Vonf and Voff from the voltage detectors 320 and 340, while capacitors C1 and C2 are discharging, and provides the acquired signals to the calculation units 72 and 92. The calculation units 72 and 92 use the acquired signals as described above to calculate the coefficients Kout1 and Kout2, which are the actual values ​​of the coefficients K1 and K2, respectively.

[0146] The abnormality detection unit 70 detects an abnormality in capacitor C1 based on the output signal Vonf of the voltage detector 320 and the appropriate voltage range of capacitor C1 calculated by the calculation unit 68. Specifically, the abnormality detection unit 70 detects an abnormality in capacitor C1 and outputs an abnormality detection signal AL1 when the voltage Von of capacitor C1 detected by the voltage detector 320 deviates from the appropriate voltage range of capacitor C1.

[0147] The abnormality detection unit 90 detects an abnormality in capacitor C2 based on the output signal Voff of the voltage detector 340 and the appropriate voltage range of capacitor C2 calculated by the calculation unit 88. Specifically, the abnormality detection unit 90 detects an abnormality in capacitor C2 and outputs an abnormality detection signal AL2 when the voltage Voff of capacitor C2 detected by the voltage detector 340 deviates from the appropriate voltage range of capacitor C2.

[0148] <Effects> As described above, according to this embodiment, the optimal voltage range of the capacitor is calculated to keep the peak value of the drive current within a normal range, based on the circuit parameters of the resonant circuit through which the drive current supplied from the capacitor to the coil flows. Then, based on this calculated optimal voltage range, a reference voltage Vref, which is the target value of the capacitor voltage, is generated. The circuit parameters of the resonant circuit include the wiring resistance and wiring inductance of the resonant circuit, the inductance and DC resistance of the coil, and the ESR and capacitance of the capacitor. With this, the peak value of the drive current can be kept within a normal range regardless of differences in circuit parameters.

[0149] Furthermore, among the circuit parameters mentioned above, the ESR of the capacitor is calculated from the ambient temperature of the capacitor. The capacitance of the capacitor is measured and calculated from the charging current and voltage of the capacitor. As a result, the reference voltage Vref also changes according to the degradation state of the capacitor and the ambient temperature, so it is possible to suppress changes in the peak value of the drive current due to the state of the capacitor. Therefore, the drive current can always be kept within the normal range regardless of the state of the capacitor.

[0150] Furthermore, in this embodiment, the coefficients K1 and K2 for converting the peak value of the drive current to the capacitor voltage are calculated using the values ​​listed in the characteristic tables or circuit design documents of each component constituting the resonant circuit as initial values ​​for the circuit parameters. Then, the coefficients K1 and K2 are corrected based on the actual peak value of the drive current and the actual value of the capacitor voltage obtained during the operation of the drive power supply. In this way, individual differences due to component variations in the resonant circuit and the degradation state of the components are reflected in the reference voltage Vref. Therefore, changes in the peak value of the drive current due to these factors can be suppressed. Thus, the peak value of the drive current can be stably kept within the normal range.

[0151] As described above, according to this embodiment, the peak value of the drive current can always be kept within the normal range, so that the mechanical switch can be operated normally and stably. Therefore, the reliability of the power supply unit including the mechanical switch can be improved.

[0152] Furthermore, according to this embodiment, since the reference voltage Vref is automatically adjusted in response to changes in circuit parameters, periodic maintenance work to check the status of the mechanical switch is unnecessary. In addition, by comparing the appropriate voltage range of the capacitor calculated from the circuit parameters with the actual voltage value of the capacitor, it is possible to detect abnormalities in the capacitor.

[0153] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims and not by the foregoing description, and all modifications within the meaning and scope of the claims are intended to be included.

[0154] 1, 5, 6, 21 VCB, 2 High-speed switch, 3 Semiconductor switch, 4 Mechanical switch, 7 Power converter, 8 Bidirectional converter, 9 Fuse, 10, 38, 322, 342 Current detector, 11 Reactor, 12, C1, C2 Capacitor, 20 Transformer, 22 Operating unit, 23 Control device, 30 Drive power supply, 32, 34 Drive circuit, 36 Charging circuit, 36a Battery, 36b DC / DC converter, 40 Mechanical contact, 42, 44 Coil, 50 Command generation unit, 52 On-off control unit, 54 On-off control unit, 56 Charging control unit, 58 Reference voltage generation unit, 60, 80 Arithmetic circuit, 61, 68, 72, 74, 76, 98 Arithmetic unit, 62 Adder, 64 Multiplier, 70, 90 Anomaly detection unit, 100, 102 Current detection unit, 110 Commercial AC power supply, 112 Load, 113 Power storage device, 230 CPU, 232 Memory, 234 I / O circuit, 236 Bus, 320, 340 Voltage detector, 324, 344 Temperature detector, D1, D2 Diodes, SW1, SW2 Switches.

Claims

1. A drive power supply for supplying a drive current to a mechanical switch, wherein the mechanical switch includes a mechanical contact and a coil that receives the drive current to open and close the mechanical contact, the drive power supply further comprises a capacitor and a switch connected between the capacitor and the coil, the switch is configured to supply the drive current from the capacitor to the coil by being temporarily turned on to turn the mechanical switch on or off, a charging circuit that charges the capacitor to a reference voltage during the off period of the switch, and a control device that controls the switch and the charging circuit, the control device calculates an appropriate voltage range for the capacitor to keep the peak value of the drive current within a predetermined normal range based on the circuit parameters of a resonant circuit through which the drive current flows, and generates the reference voltage based on the calculated appropriate voltage range of the capacitor.

2. The power supply for a mechanical switch according to claim 1, wherein the circuit parameters include the capacitance and equivalent series resistance of the capacitor, and further comprises a temperature detector for detecting the ambient temperature of the capacitor, a first current detector for detecting the charging current of the capacitor, and a voltage detector for detecting the voltage of the capacitor, and the control device measures the capacitance of the capacitor based on the detected values ​​of the first current detector and the voltage detector during the charging of the capacitor, and calculates the equivalent series resistance of the capacitor based on the detected value of the temperature detector.

3. The power supply for a mechanical switch according to claim 2, wherein the circuit parameters further include the resistance and inductance of the resonant circuit, and further comprises a second current detector for detecting the drive current, the control device calculates a coefficient for converting the peak value of the drive current to the voltage of the capacitor based on the circuit parameters, corrects the calculated coefficient based on the peak value of the drive current obtained from the detection value of the second current detector and the detection value of the voltage detector, and calculates the appropriate voltage range using the corrected coefficient.

4. The coil includes a first coil for closing the mechanical contact and a second coil for opening the mechanical contact; the capacitor includes a first capacitor and a second capacitor connected in parallel to each other to the charging circuit; the switch includes a first switch connected between the first capacitor and the first coil, which is temporarily turned on to turn on the mechanical switch to supply a first drive current from the first capacitor to the first coil; and a second switch connected between the second capacitor and the second coil, which is temporarily turned on to turn off the mechanical switch to supply a second drive current from the second capacitor to the second coil; the control device calculates a first appropriate voltage range of the first capacitor to keep the first drive current within a first normal range based on a first circuit parameter of the resonant circuit of the first drive current. A drive power supply for a mechanical switch according to any one of claims 1 to 3, comprising: calculating a second appropriate voltage range for the second capacitor to keep the second drive current within a second normal range based on a second circuit parameter of the second drive current resonant circuit; and generating the reference voltage within the range where the first appropriate voltage range and the second appropriate voltage range overlap.

5. The power supply for a mechanical switch according to claim 4, wherein the first circuit parameter includes the capacitance and equivalent series resistance of the first capacitor, the second circuit parameter includes the capacitance and equivalent series resistance of the second capacitor, the control device measures the capacitance of the first capacitor based on detected values ​​of the charging current and voltage of the first capacitor while the first capacitor is being charged, measures the capacitance of the second capacitor based on detected values ​​of the charging current and voltage of the second capacitor while the second capacitor is being charged, calculates the equivalent series resistance of the first capacitor based on a detected value of the temperature of the first capacitor, and calculates the equivalent series resistance of the second capacitor based on a detected value of the temperature of the second capacitor.

6. The control device calculates a first coefficient for converting the peak value of the first drive current to the voltage of the first capacitor based on the first circuit parameters; corrects the calculated first coefficient based on the peak value of the first drive current obtained from the detected value of the first drive current and the detected value of the voltage of the first capacitor; calculates a first appropriate voltage range using the corrected first coefficient; calculates a second coefficient for converting the peak value of the second drive current to the voltage of the second capacitor based on the second circuit parameters; corrects the calculated second coefficient based on the peak value of the second drive current obtained from the detected value of the second drive current and the detected value of the voltage of the second capacitor; and calculates a second appropriate voltage range using the corrected second coefficient, the drive power supply for a mechanical switch according to claim 5.

7. The power supply for a mechanical switch according to claim 5, wherein the control device detects an abnormality in the first capacitor when the detected voltage of the first capacitor deviates from the first appropriate voltage range, and detects an abnormality in the second capacitor when the detected voltage of the second capacitor deviates from the second appropriate voltage range.

8. A mechanical switch having a first terminal that receives an AC voltage supplied from an AC power source and a second terminal connected to a load; a power converter connected between the second terminal of the mechanical switch and a power storage device; a control device configured to turn on the mechanical switch when the AC power source is normal and to turn off the mechanical switch when the AC power source is abnormal; and a drive power supply that receives instructions from the control device and supplies a drive current to the mechanical switch, wherein the mechanical switch includes a mechanical contact and a coil that opens and closes the mechanical contact in response to the supply of the drive current; the drive power supply includes a capacitor and a switch connected between the capacitor and the coil, wherein the switch is configured to be temporarily turned on to turn the mechanical switch on or off in order to supply the drive current from the capacitor to the coil; the drive power supply further includes a charging circuit that charges the capacitor to a reference voltage during the off period of the switch; and the control device calculates an appropriate voltage range for the capacitor to keep the peak value of the drive current within a predetermined normal range based on the circuit parameters of the circuit through which the drive current flows. A power supply device that generates the reference voltage based on the calculated appropriate voltage range of the capacitor.

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