WO2015087488A1

WO2015087488A1 - Power supply

Info

Publication number: WO2015087488A1
Application number: PCT/JP2014/005767
Authority: WO
Inventors: 公彦古川
Original assignee: 三洋電機株式会社
Priority date: 2013-12-11
Filing date: 2014-11-18
Publication date: 2015-06-18
Also published as: JP6456843B2; JPWO2015087488A1

Abstract

This power supply economically suppresses the effects of ripple when charging a secondary battery in a vehicle from a commercial power supply. In this power supply (10) for mounting in a vehicle (100), a secondary battery (E1) supplies power to a traction motor (40). A current detection element detects the current in the secondary battery (E1). A current detection circuit (12) acquires the signal voltage of the current detection element via a low pass filter, and, from the acquired voltage value, estimates the current value of the current in the secondary battery (E1). The low pass filter is configured to allow selection of at least a first blocking frequency and a second blocking frequency lower than the first blocking frequency, and when charging the secondary battery (E1) from a power supply outside of the vehicle, the second blocking frequency is selected.

Description

Power supply

The present invention relates to a power supply device to be mounted on a vehicle.

In recent years, plug-in hybrid vehicles (PHV) and electric vehicles (EV) have become widespread. In PHV and EV, it is necessary to charge a battery in the vehicle from outside the vehicle with a dedicated charging cable. There are two types of chargers: ordinary chargers and quick chargers. Ordinary chargers require more time to charge than quick chargers, but they can be fully charged and equipment installation costs can be kept low. It is assumed to be installed in a place where parking is done for a long time, such as a house, office, or rental parking lot. On the other hand, the quick charger can be charged 80% in a short time, but the equipment introduction cost becomes high. Installation in places where the staying time is short, such as shopping centers, gas stations, and highways SA, is assumed.

In Japan, a single-phase AC 200V or 100V commonly used at home is used as a power source for an ordinary charger. Three-phase AC 200V is used for the power supply of the quick charger. Since a normal charger uses a single-phase power supply, a large amount of power ripple occurs at a low cost. On the other hand, the quick charger uses three-phase alternating current, and therefore has high power transportation efficiency and small power ripple. However, when used in a general household, it is necessary to lay a dedicated line.

JP 2013-90473 A

When charging from commercial power, ripple occurs in the charging current. In particular, when single-phase alternating current is used, the ripple is larger than when three-phase alternating current is used. When the influence of ripple becomes large, it becomes impossible to detect an accurate current on the secondary battery side. If a large-scale smoothing filter is provided on the output side of the charger, the ripple can be reduced but the cost is increased.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for suppressing the influence of ripples at low cost when charging a secondary battery in a vehicle from a commercial power source.

In order to solve the above-described problems, a power supply device according to an aspect of the present invention is a power supply device to be mounted in a vehicle, the secondary battery for supplying power to a traveling motor, and the secondary battery A current detection element for detecting a current flowing through the low-pass filter, a low-pass filter having a predetermined cutoff frequency characteristic and passing a signal equal to or lower than the cutoff frequency, and obtaining the signal voltage of the current detection element via the low-pass filter And a current detection circuit that estimates a current value of a current flowing through the secondary battery from the acquired voltage value. The low-pass filter is configured to be able to select at least a first cutoff frequency characteristic and a second cutoff frequency characteristic lower than the first cutoff frequency characteristic, and the secondary battery is charged from a power source outside the vehicle. When done, the second cutoff frequency is selected.

According to the present invention, when charging a secondary battery in a vehicle from a commercial power source, the influence of ripple can be suppressed at low cost.

It is a figure which shows the structure of the vehicle carrying the power supply device which concerns on embodiment of this invention. It is a block diagram which shows the structural example of a vehicle-mounted charger. It is a figure which shows transition of a voltage (AC), an electric current (AC), electric power, and a charging current at the time of charging with single phase alternating current 100V from a normal charger. It is a figure which shows the electric current which flows into a secondary battery, and a sampling period. It is a figure which shows the 1st structural example of the current detection circuit which concerns on embodiment. It is a figure which shows the 2nd structural example of the current detection circuit which concerns on embodiment.

FIG. 1 is a diagram showing a configuration of a vehicle 100 equipped with a power supply device 10 according to an embodiment of the present invention. In the present embodiment, a plug-in hybrid vehicle (PHV) or an electric vehicle (EV) that can be charged from a commercial power source (system power source) is assumed as the vehicle 100.

The vehicle 100 includes a power supply device 10, an in-vehicle charger 20, an inverter 30, and a traveling motor 40. The power supply device 10 includes a secondary battery E1, a shunt resistor Rs, a voltage detection circuit 11, a current detection circuit 12, and a control circuit 13. The secondary battery E <b> 1 is a secondary battery for storing energy for supplying electric power to the traveling motor 40. For the secondary battery E1, for example, a nickel metal hydride battery or a lithium ion battery can be used. The secondary battery E1 is configured by connecting a plurality of battery cells in series or in series and parallel.

The secondary battery E1 is charged from a power source installed outside the vehicle 100. As described above, the charging equipment is roughly classified into a normal charger and a quick charger. In vehicle 100, a normal charging path for charging secondary battery E1 from the normal charger and a quick charging path for charging secondary battery E1 from the quick charger are separately provided.

On the normal charging path, an in-vehicle charger 20, a first normal charging switch S5, and a second normal charging switch S6 are provided. The in-vehicle charger 20 converts AC power input from an external ordinary charger connected by a charging cable into DC power and outputs the DC power to the secondary battery E1. The on-vehicle charger 20 notifies the control circuit 13 of the start and end of normal charging.

The first normal charging switch S5 is inserted into the wiring between the positive terminal of the in-vehicle charger 20 and the positive terminal of the secondary battery E1, and the second normal charging switch S6 is connected to the negative terminal of the in-vehicle charger 20 and the secondary terminal. It is inserted into the wiring between the negative terminals of the battery E1. A relay can be used for the first normal charging switch S5 and the second normal charging switch S6. The control circuit 13 controls the first normal charging switch S5 and the second normal charging switch S6 to the on state during normal charging, and the off state at other times.

A first rapid charge switch S3 and a second rapid charge switch S4 are provided on the rapid charge path. The first quick charge switch S3 is inserted into the wiring between the positive terminal of the quick charge plug and the positive terminal of the secondary battery E1, and the second quick charge switch S4 is the negative terminal of the quick charge plug. And inserted into the wiring between the negative terminals of the secondary battery E1. A relay can also be used for the first quick charge switch S3 and the second quick charge switch S4. The control circuit 13 controls the first quick charge switch S3 and the second quick charge switch S4 to be in an on state at the time of quick charge, and is controlled to be in an off state at other times.

FIG. 2 is a block diagram illustrating a configuration example of the in-vehicle charger 20. The in-vehicle charger 20 includes an input filter 21, a full-wave rectifier circuit 22, a PFC (Power Factor Correction) circuit 23, and an insulated DC-DC converter 24.

The input filter 21 passes only the commercial power frequency component from the commercial power AC power supplied from the ordinary charger and outputs it to the full-wave rectifier circuit 22. The full-wave rectification circuit 22 performs full-wave rectification on the AC power input from the input filter 21 and outputs it to the PFC circuit 23. The full-wave rectifier circuit 22 is configured by, for example, a diode bridge circuit in which four rectifier diodes are connected in a bridge configuration. The DC power that has been full-wave rectified by the full-wave rectifier circuit 22 includes ripples. The PFC circuit 23 improves the power factor of the DC power input from the full-wave rectifier circuit 22 and outputs the power factor to the isolated DC-DC converter 24.

The insulated DC-DC converter 24 converts the DC voltage input from the PFC circuit 23 into a set DC voltage and supplies it to the secondary battery E1. The insulation type DC-DC converter 24 monitors the output voltage and output current to the secondary battery E1, and performs constant current charging (CC charging) or constant voltage charging (CV charging). The isolated DC-DC converter 24 may be a flyback DC-DC converter, a forward DC-DC converter (push-pull DC-DC converter, half-bridge DC-DC converter, full-bridge DC-DC converter), or the like. .

Return to Figure 1. The inverter 30 converts the DC power supplied from the secondary battery E <b> 1 into AC power and supplies it to the traveling motor 40 during power running. During regeneration, the AC power supplied from the traveling motor 40 is converted to DC power and supplied to the secondary battery E1.

The traveling motor 40 may be a large motor capable of self-running, or a small motor that assists in engine traveling (mainly during starting and acceleration). In the EV and strong type PHV, the former large motor is used, and in the small PHV, the latter small motor is used. The traveling motor 40 rotates according to the DC power supplied from the inverter 30 during powering. At the time of regeneration, the rotational energy due to deceleration is converted to DC power and supplied to the inverter 30.

The first main switch S1 is inserted between the path connecting the plus terminal of the secondary battery E1 and the plus terminal of the inverter 30. Further, a series circuit of a precharge switch Sp and a precharge resistor Rp is connected in parallel with the first main switch S1. The second main switch S2 is inserted between the path connecting the negative terminal of the secondary battery E1 and the negative terminal of the inverter 30. Relays can be used for the first main switch S1, the second main switch S2, and the precharge switch Sp.

The control circuit 13 controls the first main switch S1 and the second main switch S2 to be in an on state during traveling, and electrically connects the power supply apparatus 10 and the power system. When not running, the control circuit 13 controls the first main switch S1 and the second main switch S2 to be in an off state as a rule, and electrically shuts off the power supply device 10 and the power system. When the traveling motor 40 is started, the control circuit 13 turns on the precharge switch Sp before turning on the first main switch S1 and the second main switch S2. As a result, a capacitor (not shown) connected in parallel to the inverter 30 can be precharged, and the inrush current when the first main switch S1 and the second main switch S2 are turned on can be suppressed.

The voltage detection circuit 11 detects the voltage of each battery cell constituting the secondary battery E1. The voltage detection circuit 11 outputs the detected voltage value of each battery cell to the control circuit 13. The voltage detection circuit 11 is configured by ASIC (Application Specific Integrated Circuit) which is a dedicated custom IC.

The shunt resistor Rs is connected in series to the negative terminal of the secondary battery E1. The shunt resistor Rs is a current detection element for detecting a current flowing through the secondary battery E1. As the current detection element, a Hall element may be used instead of the shunt resistor Rs. The insertion position of the shunt resistor Rs may be any position as long as it is on a path in which a plurality of battery cells are connected in series.

The current detection circuit 12 detects the value of the current flowing through the secondary battery E1 based on the voltage across the shunt resistor Rs. The current detection circuit 12 outputs the detected current value to the control circuit 13. The control circuit 13 is composed of a microcomputer and controls the entire power supply device 10. Details of the current detection circuit 12 and the control circuit 13 will be described later.

When charging from a commercial power source, if the charger does not have sufficient ripple removal capability, a ripple current may be generated according to the power ripple. In the case of quick charging, a high-performance quick charger is used, so that sufficient ripple removal capability can be secured. Specifically, a large smoothing capacitor can be installed on the secondary side of the insulated DC-DC converter to increase the ripple removal capability. In Japan, three-phase alternating current is used for the power supply of the quick charger, so that the generated ripple is reduced.

On the other hand, since a single-phase alternating current is used for the power supply of the normal charger, the ripple becomes large. Although it is conceivable to install a large smoothing capacitor on the secondary side of the insulated DC-DC converter 24 of the in-vehicle charger 20, the cost is increased and the circuit scale is increased. In-vehicle chargers require a small charger at the lowest possible cost. In consideration of cost reduction of the charger, it is desired that the battery can be charged while leaving some ripples.

FIG. 3 is a diagram showing the transition of voltage (AC), current (AC), power, and charging current when charging with a single-phase AC 100 V from a normal charger. The charging current (load current) is a fixed value. The frequency of the commercial power supply is 50/60 Hz, and 50 Hz is assumed in the following description. Since the voltage (AC) and current (AC) have the same frequency, the frequency of the generated power ripple is twice the commercial frequency. A ripple current having a frequency twice the commercial frequency is also generated in the charging current obtained by dividing the power by the battery voltage.

∙ The ripple current generated during charging changes regularly because it is determined by the frequency of the commercial power supply. On the other hand, the ripple current generated during traveling tends to vary irregularly because it depends on the load during traveling. Therefore, in a hybrid vehicle (HV) that is not charged from a commercial power source, the ripple current rarely adversely affects voltage detection, current detection, and the like.

The control cycle in the power supply device 10 including the sampling cycle of the voltage detection circuit 11 and the current detection circuit 12 is set to a relatively low speed. For example, it is set to 10 ms (= 100 Hz). 10 ms is sufficient as the control cycle of the secondary battery for in-vehicle use, and even if it is set to a control cycle higher than this, it becomes overspec.

When the secondary battery E1 is charged from a commercial power supply of 50 Hz and the voltage value and current value of the secondary battery E1 are sampled at 10 ms (= 100 Hz), the ripple frequency and the sampling frequency match. If the frequencies match, the ripple current will adversely affect current detection.

FIG. 4 is a diagram showing a current flowing through the secondary battery E1 and a sampling cycle. FIG. 4 shows an example in which current is sampled at a period of 10 ms. The average value is sampled (see the middle arrow), the worst maximum is sampled (see the upper arrow), and the worst minimum is sampled (lower). (See arrow in). If the average value of the charging current can be sampled, an error does not occur between the actual current value and the detected current value, but an error occurs in the case of sampling other than the average value. The larger the sampling point is, the larger the error. The detected current value is used even if it is integrated. For example, the SOC (State Of Charge) of the secondary battery E1 is calculated based on the integrated current value. Even if the error between the actual current value and the detected current value is small, the integrated value may cause a large error. When the sampling frequency is 100 Hz, a component having a Nyquist frequency of 50 Hz or more becomes a false signal, which is likely to cause a large error.

Generally, components above the Nyquist frequency are removed by a passive anti-aliasing filter composed only of passive elements such as capacitors, coils, and resistors. However, the anti-aliasing filter that sufficiently attenuates the high-frequency component has a large individual difference due to component variation.

When a battery is running, a large ripple current at a specific frequency is unlikely to occur as when charging from a commercial power source, and the current detection error due to this is small. For this reason, in a type of HV that is not charged from a commercial power source, it is common to set the cutoff frequency of the anti-aliasing filter to be slightly lower than the Nyquist frequency. The necessary band for current detection depends on the control frequency. For example, when sampling is performed at a cycle of 100 Hz, the filter is designed to attenuate from around 50 Hz or more. This is because the voltage detection and current detection are synchronized.

In contrast, PHV and EV that are charged from a commercial power source generate a large ripple current when charged from the commercial power source. In this case, if a filter having a cutoff frequency slightly lower than the Nyquist frequency is used, there is a high possibility that an accurate current value and current integrated value cannot be obtained.

This problem can be solved by setting the sampling frequency sufficiently higher than the ripple frequency (for example, 4 times or more), but a higher-speed microcomputer is required. A high-speed microcomputer increases the cost and power consumption.

So far, the current detection error due to the ripple current has been described. Regarding the voltage detection error, since the internal resistance of the battery is small, the rise of the ripple voltage is limited even if a large ripple current is generated. For this reason, the voltage detection error is not as big a problem as the current detection error. Hereinafter, a method for reducing the current detection error without using a large passive filter will be described.

FIG. 5 is a diagram illustrating a first configuration example of the current detection circuit 12 according to the embodiment. In the first configuration example, the current detection circuit 12 includes an amplifier circuit 121a and an A / D converter 123. The amplifier circuit 121a amplifies the voltage across the shunt resistor Rs with a predetermined gain and outputs the amplified voltage to the A / D converter 123. The A / D converter 123 converts the analog signal input from the amplifier circuit 121 a into a digital signal and outputs the digital signal to the control circuit 13.

The amplifier circuit 121a includes a first operational amplifier OP1, a first input resistor R1, a first feedback resistor R2, a first feedback capacitor C1, an additional capacitor Ca, and a mode changeover switch M1. These elements constitute a low-pass filter. The low-pass filter shown in FIG. 5 is a primary low-pass filter.

The non-inverting input terminal and the inverting input terminal of the first operational amplifier OP1 are respectively connected to both ends of the shunt resistor Rs. Specifically, the high potential side terminal of the shunt resistor Rs is connected to the non-inverting input terminal of the first operational amplifier OP1, and the low potential side terminal of the shunt resistor Rs is connected to the inverting input terminal of the first operational amplifier OP1.

The first input resistor R1 is connected between the inverting input terminal of the first operational amplifier OP1 and the low potential side terminal of the shunt resistor Rs. A first feedback resistor R2 is connected between the inverting input terminal of the first operational amplifier OP1 and the output terminal of the first operational amplifier OP1. A first feedback capacitor C1 is connected in parallel with the first feedback resistor R2 between the inverting input terminal of the first operational amplifier OP1 and the output terminal of the first operational amplifier OP1. Further, an additional capacitor Ca is connected in parallel with the first feedback resistor R2 and the first feedback capacitor C1 between the inverting input terminal of the first operational amplifier OP1 and the output terminal of the first operational amplifier OP1. A mode switch M1 is inserted between the inverting input terminal of the first operational amplifier OP1 and the additional capacitor Ca.

A MOSFET, a photo relay, a photo coupler, or the like can be used for the mode switch M1. The mode switch M1 is turned on / off in response to a control signal from the control circuit 13. In order to insulate the amplifier circuit 121a from the control circuit 13, it is desirable to use a photorelay or a photocoupler for the mode changeover switch M1.

Since it can be assumed that the inverting input terminal of the first operational amplifier OP1 is virtually grounded, the gain Av of the amplifier circuit 121a is equal to the resistance value of the first input resistor R1 and the first feedback resistor R2, as shown in the following equation (1). It is set based on the ratio of resistance values. Further, since the configuration of the amplifier circuit 121a shown in FIG. 5 is a configuration of a non-inverting amplifier, the sign of the gain A is positive. When the inverting amplifier configuration is adopted, the sign of gain A is negative.

Av = (R2 / R1) +1 Formula (1)
The control circuit 13 can change the transfer characteristic of the amplifier circuit 121a by switching on / off of the mode switch M1. During charging of the secondary battery E1 from the AC power supply outside the vehicle, the control circuit 13 controls the mode switch M1 to be in an ON state, thereby lowering the high-frequency cutoff frequency of the amplifier circuit 121a. More specifically, the control circuit 13 lowers the high-frequency cutoff frequency of the amplifier circuit 121a while the secondary battery E1 is charged with the DC power generated by full-wave rectification of the AC power of the commercial power supply. That is, the control circuit 13 controls the mode switch M1 to be in an on state during the charging mode, and controls the mode switch M1 to be in an off state during other modes.

The quick charge mode may be included or excluded from the charge mode. As described above, since the ripple current at the time of rapid charging using three-phase alternating current is relatively small, the current detection error can be suppressed to a low level without reducing the high-frequency cutoff frequency of the amplifier circuit 121a. Further, the regenerative charging mode may be included or excluded from the charging mode. Since the ripple of the electric power generated by the traveling motor 40 based on the deceleration energy changes irregularly and the high frequency component is relatively small, the current detection error can be achieved without lowering the high frequency cutoff frequency of the amplifier circuit 121a. Can be kept small. On the other hand, since the ripple current during normal charging is large, it is necessary to lower the high-frequency cutoff frequency of the amplifier circuit 121a to attenuate more high-frequency components.

The first high-frequency cutoff frequency fc1 and the second high-frequency cutoff frequency fc2 of the amplifier circuit 121a that functions as a primary low-pass filter are expressed by the following equations (2) and (3). Equation (2) represents the high-frequency cutoff frequency fc1 when the mode changeover switch M1 is in the off state, and Equation (3) represents the high-frequency cutoff frequency fc2 when the mode changeover switch M1 is in the on state. As described above, the low-pass filter has a configuration capable of selecting the first cutoff frequency fc and the second cutoff frequency f2 lower than the first cutoff frequency.

fc1 = 1 / (2π · R2 / C1) (2)
fc1 = 1 / (2π · R2 / (C1 + Ca) (3)
If gain Av = 50, high frequency cutoff frequency fc1 = 48 Hz during driving, and high frequency cutoff frequency fc2 = 10 Hz during charging, for example, circuit constants are R1 = 1 kΩ, R2 = 49 kΩ, C1 = 67 nF, Ca = What is necessary is just to set to 257 nF.

FIG. 6 is a diagram illustrating a second configuration example of the current detection circuit 12 according to the embodiment. In the second configuration example, the current detection circuit 12 includes a first amplifier circuit 121b, a second amplifier circuit 121c, a multiplexer 122, and an A / D converter 123. In the configuration example 2, two amplifier circuits having different transfer characteristics are provided.

The first amplifier circuit 121b amplifies the voltage across the shunt resistor Rs with a predetermined gain and outputs the amplified voltage to the multiplexer 122. The second amplifier circuit 121c is connected in parallel with the first amplifier circuit 121b, amplifies the voltage across the shunt resistor Rs with a predetermined gain, and outputs the amplified voltage to the multiplexer 122. The multiplexer 122 selects the output of the first amplifier circuit 121 b and the output of the second amplifier circuit 121 c and outputs them to the A / D converter 123. The A / D converter 123 converts the analog signal input from the multiplexer 122 into a digital signal and outputs the digital signal to the control circuit 13.

The first amplifier circuit 121b includes a first operational amplifier OP1, a first input resistor R1, a first feedback resistor R2, and a first feedback capacitor C1, and these elements constitute a low-pass filter. The non-inverting input terminal and the inverting input terminal of the first operational amplifier OP1 are respectively connected to both ends of the shunt resistor Rs. Specifically, the high potential side terminal of the shunt resistor Rs is connected to the non-inverting input terminal of the first operational amplifier OP1, and the low potential side terminal of the shunt resistor Rs is connected to the inverting input terminal of the first operational amplifier OP1.

The first input resistor R1 is connected between the inverting input terminal of the first operational amplifier OP1 and the low potential side terminal of the shunt resistor Rs. A first feedback resistor R2 is connected between the inverting input terminal of the first operational amplifier OP1 and the output terminal of the first operational amplifier OP1. Further, a first feedback capacitor C1 is connected in parallel with the first feedback resistor R2 between the inverting input terminal of the first operational amplifier OP1 and the output terminal of the first operational amplifier OP1.

The second amplifier circuit 121c includes a second operational amplifier OP2, a second input resistor R3, a second feedback resistor R4, and a second feedback capacitor C2, and these elements constitute a low-pass filter. The non-inverting input terminal and the inverting input terminal of the second operational amplifier OP2 are respectively connected to both ends of the shunt resistor Rs. Specifically, the high potential side terminal of the shunt resistor Rs is connected to the non-inverting input terminal of the second operational amplifier OP2, and the low potential side terminal of the shunt resistor Rs is connected to the inverting input terminal of the second operational amplifier OP2.

The second input resistor R3 is connected between the inverting input terminal of the second operational amplifier OP2 and the low potential side terminal of the shunt resistor Rs. A second feedback resistor R4 is connected between the inverting input terminal of the second operational amplifier OP2 and the output terminal of the second operational amplifier OP2. Further, a second feedback capacitor C2 is connected in parallel with the second feedback resistor R4 between the inverting input terminal of the second operational amplifier OP2 and the output terminal of the second operational amplifier OP2.

The first amplifier circuit 121b is designed to be equivalent to a circuit in which the mode switch M1 of the amplifier circuit 121a shown in FIG. The second amplifier circuit 121c is designed to be equivalent to a circuit in which the mode switch M1 of the amplifier circuit 121a shown in FIG. For this purpose, the capacitance value of the second feedback capacitor C2 is set larger than the capacitance value of the first feedback capacitor C1. Other circuit constants and operational amplifier specifications are set to be the same for the first amplifier circuit 121b and the second amplifier circuit 121c.

The control circuit 13 can change the transfer characteristic of the amplifier circuit by inputting a switching signal to the multiplexer 122. Specifically, during charging of the secondary battery E1 from the AC power supply outside the vehicle, the control circuit 13 inputs a switching signal for selecting the output of the second amplifier circuit 121c to the multiplexer 122, whereby the amplifier circuit Lower the high frequency cutoff frequency. That is, the control circuit 13 inputs a switching signal for selecting the output of the second amplifier circuit 121c in the charging mode to the multiplexer 122, and outputs a switching signal for selecting the output of the first amplifier circuit 121b in the other modes. Input to the multiplexer 122. Whether or not to include the quick charge mode and / or the regenerative charge mode in the charge mode is as described above.

As described above, according to the present embodiment, when the transfer characteristic of the amplifier circuit in the current detection circuit 12 is switched according to the mode, the secondary battery E1 in the vehicle is charged from the commercial power source. Reduces ripple effects at low cost. That is, since the current detection sampling frequency is close to the commercial power supply ripple frequency, current detection errors may accumulate. In contrast, in the present embodiment, when charging from a commercial power source, the current detection error can be reduced by lowering the high-frequency cutoff frequency of the amplifier circuit and cutting more high-frequency components. When the commercial power source is not charged, high-precision current detection can be realized by setting the high-frequency cutoff frequency of the amplifier circuit in the vicinity of the Nyquist frequency of the sampling frequency.

In addition, it is not necessary to enlarge the smoothing filter of the charger by applying a large low-pass filter in the amplification circuit in the current detection circuit 12 during charging. Therefore, the cost increase of the charger can be suppressed.

When the amplifier circuit in the current detection circuit 12 is configured as shown in FIG. 5, an increase in the number of parts can be minimized, and an increase in circuit area can be minimized. Depending on the price of the photorelay used for the mode changeover switch M1, there may be a case where it is cheaper to provide two amplifier circuits having the same circuit configuration and different filter characteristics as shown in FIG.

The present invention has been described based on the embodiments. Those skilled in the art will understand that these embodiments are exemplifications, and that various modifications can be made to the combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. By the way.

For example, in the configuration example 2 shown in FIG. 6, the multiplexer 122 is provided, and the output of the first amplifier circuit 121b and the output of the second amplifier circuit 121c are selected according to the mode. In the modification of the configuration example 2, the multiplexer 122 is not provided, and two A / D converters for the first amplifier circuit 121b and the second amplifier circuit 121c are provided. The control circuit 13 selects the output digital value of the first amplifying circuit 121b and the output digital value of the second amplifying circuit 121c respectively input from the two AD converters according to the mode.

In the above embodiment, the example in which the shunt resistor Rs is used as the current detection element has been described. However, a Hall element may be used instead of the shunt resistor Rs. In that case, since a voltage value corresponding to the current value is obtained directly from the Hall element, a passive filter composed only of passive elements can be used instead of an active filter having an amplification function using the above-described operational amplifier. In that case as well, the first cutoff frequency characteristic and the second cutoff frequency characteristic can be selected by varying the capacitance value of the capacitor.

100 vehicle, E1 secondary battery, Rs shunt resistor, S1 first main switch, S2 second main switch, Sp precharge switch, Rp precharge resistor, S3 first quick charge switch, S4 second quick charge switch, S5 first normal charge switch, S6 second normal charge switch, 10 power supply, 11 voltage detection circuit, 12 current detection circuit, 121a amplifier circuit, OP1 first operational amplifier, R1 first input resistance, R2 first feedback resistance , C1 first feedback capacitor, Ca additional capacitor, M1 mode changeover switch, OP2 second operational amplifier, R3 second input resistor, R4 second feedback resistor, C2 second feedback capacitor, 121b first amplifier circuit, 121c second amplifier circuit , 1 2 multiplexer, 123 A / D converter, 13 a control circuit, 20 on-board charger, 21 input filter, 22 a full-wave rectifier circuit, 23 PFC circuit, 24 isolated DC-DC converter, 30 inverter, 40 running motor.

Claims

A power supply device to be mounted in a vehicle,
A secondary battery for supplying electric power to the traveling motor;
A current detection element for detecting a current flowing in the secondary battery;
A low-pass filter having a predetermined cutoff frequency characteristic and passing a signal below the cutoff frequency;
A current detection circuit that acquires a signal voltage of the current detection element via the low-pass filter and estimates a current value of a current flowing through the secondary battery from the acquired voltage value; and
The low-pass filter is configured to be able to select at least a first cutoff frequency characteristic and a second cutoff frequency characteristic lower than the first cutoff frequency characteristic, and the secondary battery is charged from a power source outside the vehicle. And a second cutoff frequency is selected.
The low-pass filter is
An operational amplifier connected to both ends of the current detection element;
An input resistor connected between one end of the current detection element and one input terminal of the operational amplifier;
A feedback resistor connected between one input terminal of the operational amplifier and an output terminal of the operational amplifier;
A first feedback capacitor connected in parallel with the feedback resistor between one input terminal of the operational amplifier and an output terminal of the operational amplifier;
An additional capacitor connected in parallel with the feedback resistor and the first feedback capacitor between one input terminal of the operational amplifier and the output terminal of the operational amplifier;
A switch inserted between one input terminal of the operational amplifier and the additional capacitor,
The power supply device according to claim 1, wherein the switch is turned on in a charging mode and turned off in a non-charging mode.
The low-pass filter includes a first amplifier circuit and a second amplifier circuit,
The first amplifier circuit includes:
A first operational amplifier connected to both ends of the current detection element;
A first input resistor connected between one end of the current detection element and one input terminal of the first operational amplifier;
A first feedback resistor connected between one input terminal of the first operational amplifier and an output terminal of the first operational amplifier;
A first feedback capacitor connected in parallel with the first feedback resistor between one input terminal of the first operational amplifier and an output terminal of the first operational amplifier;
The second amplifier circuit includes:
A second operational amplifier connected to both ends of the current detection element;
A second input resistor connected between one end of the current detection element and one input terminal of the second operational amplifier;
A second feedback resistor connected between one input terminal of the second operational amplifier and an output terminal of the second operational amplifier;
A second feedback capacitor connected in parallel with the second feedback resistor between one input terminal of the second operational amplifier and an output terminal of the second operational amplifier;
A capacitance value of the second feedback capacitor is set larger than a capacitance value of the first feedback capacitor;
The current detection circuit includes:
A selection circuit for selecting an output of the first amplifier circuit and an output of the second amplifier circuit;
2. The power supply device according to claim 1, wherein the selection circuit selects an output of the second amplification circuit in a charging mode and selects an output of the first amplification circuit in a non-charging mode.
The low-pass filter is configured to pass a signal having a frequency equal to or lower than the second cutoff frequency while DC power generated by full-wave rectification of AC power of a commercial power supply is charged in the secondary battery. The power supply device according to any one of claims 1 to 3.