WO2017022601A1

WO2017022601A1 - Charging device

Info

Publication number: WO2017022601A1
Application number: PCT/JP2016/072096
Authority: WO
Inventors: 永呉岸本; 庄司　浩幸; 尊衛嶋田; 高橋　直也; 史宏佐藤; 門田　圭司
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2015-08-06
Filing date: 2016-07-28
Publication date: 2017-02-09
Also published as: JPWO2017022601A1

Abstract

The objective of the present invention is to improve the reliability of a charging device while maintaining a high battery charging efficiency. When a battery voltage Vbatt is less than VbattL, a situation in which surplus power Pdump is generated, a voltage command value sent to a first converter 107 is controlled in such a way that a power output P1out output from the first converter 107 changes from the state indicated by the dotted line to the state indicated by the solid line. By this means, the power output P1out output by the first converter 107 tracks a power output P2out output by a second converter 108. As a result, a rise in a link voltage Vlink can be suppressed in such a way that the link voltage Vlink changes from the state indicated by the dotted line to the state indicated by the solid line.

Description

Charger

The present invention relates to a charging device.

In recent years, electric vehicles and plug-in hybrid vehicles have become widespread. These vehicles are equipped with a battery for supplying electric power to the motor when the vehicle is running. When charging this battery from a commercial AC power source, a charging device having a high conversion efficiency and a function of insulating the AC power source and the battery is required to safely charge with less power. Patent Document 1 discloses a charging device that includes an AC-DC converter and a resonant DC-DC converter, and aims to improve conversion efficiency by increasing the input voltage of the resonant DC-DC converter as the battery voltage increases. Has been.

JP 2012-85378 A

When the battery voltage is low, the output power difference between the first converter that converts the input power to a DC voltage and outputs it, and the second converter that steps down the DC voltage on the output side of the first converter and supplies it to the battery As a result, the voltage between the first converter and the second converter increases, and the reliability of the first converter and the second converter may decrease.

The charging device according to the present invention includes a first converter that converts input power into a DC voltage and outputs the output, and a control unit that outputs a command value to the first converter and controls the power on the output side of the first converter. A second converter that steps down the DC voltage on the output side of the first converter and supplies the DC voltage to the battery, and the control unit outputs a command value so that the voltage on the output side of the first converter drops to a predetermined voltage. Then, the first converter is controlled.

According to the present invention, it is possible to improve the reliability of the charging device while maintaining the charging of the battery with high efficiency.

It is a system block diagram which applied the charging device to the electric vehicle. (A) (b) is a graph which shows the factor by which a link voltage rises. It is a graph which shows suppression of a raise of a link voltage. It is a graph which shows suppression of a raise of a link voltage. It is a figure which shows control of a charge control apparatus. It is a system configuration figure in a 2nd embodiment.

(First embodiment)
FIG. 1 is a system configuration diagram in which the charging device 104 according to the first embodiment is applied to an electric vehicle 101.
The charging device 104 is supplied with AC power from the AC power source 100. The AC power supply 100 is a power supply provided at a charging stand or at home. Charging device 104 uses AC power supply 100 as a power source, converts AC power into DC power, and charges battery 102.

The electric vehicle 101 is a vehicle using the battery 102 as a power source. Although not shown, the electric power of the battery 102 is supplied to the inverter device, and the inverter device converts the electric power of the battery 102 from direct current to alternating current and supplies it to the motor. The electric vehicle 101 travels using this motor as a power source.

Vehicle ECU 103 is a device that is mounted in electric vehicle 101 and controls the operation of the electric vehicle. The vehicle ECU 103 sends operation command values such as a charging power command value Pchg *, a charging current limit value Ichglim *, and a charging voltage command value Vchg * to the charging control device 105 in the charging device 104.

The charging control device 105 is a device that controls the charging device 104, and based on a command value received from the vehicle ECU 103, the AC-DC converter 106, the first converter 107, and the second converter 108 that constitute the charging device 104. Take control.

The AC-DC converter 106 is a power converter that converts AC power into DC power. The AC voltage supplied from the AC power supply 100 is full-wave rectified by diodes D11 to D14 connected in a bridge. In the present embodiment, the diodes D11 and D12 and the diodes D13 and D14 are connected in series, and the diodes connected in series are connected in parallel to form a bridge connection. A connection point between the diodes D11 and D12 connected in series and a connection point between the diodes D13 and D14 connected in series is an AC terminal. The AC power supply 100 is connected to this AC terminal. The connection points at both ends of the diodes D11 and D12 connected in series and the diodes D13 and D14 connected in series are DC terminals. The full-wave rectified voltage is input to a booster circuit including a reactor L1 connected to a DC terminal, a switching element Q10, a diode D10, and a capacitor C1. With this booster circuit, the switching element Q10 is switched on and off, and the full-wave rectified voltage is boosted and output as a smoothed DC voltage. Note that the switching operation signal of the switching element Q10 is output from the charge control device 105.

The first converter 107 is a power converter that converts a DC voltage obtained by boosting and smoothing a full-wave rectified voltage into an insulated DC voltage. The first converter 107 includes switching elements Q1 to Q4 that are bridge-connected. The switching elements Q1 to Q4 are bridge-connected by connecting in parallel a first arm in which switching elements Q1 and Q2 are connected in series and a second arm in which switching elements Q3 and Q4 are connected in series. The both ends of the first arm are between the DC voltage terminals, and the series connection point of the switching elements Q1 and Q2 and the series connection point of the switching elements Q3 and Q4 are between the AC voltage terminals. Note that anti-parallel diodes D1 to D4 are connected to the switching elements Q1 to Q4, respectively.

Furthermore, the first converter 107 has a primary side winding in which a resonance capacitor Cr1 and a resonance reactor Lr1 are connected in series at a connection point between the switching element Q1 and the switching element Q2, and this primary side winding is magnetically coupled. A transformer T1 including a secondary winding is provided. The secondary winding of the transformer T1 is provided with bridge-connected diodes D21 to D24. Between the series connection point of the diodes D21 and D22 and the series connection point of the diodes D23 and D24 is connected between the AC terminals and connected to the secondary winding.

In the rectifier circuit composed of diodes D21 to D24, a first diode leg in which diodes D21 and D22 are connected in series and a second diode leg in which diodes D23 and D24 are connected in series are connected in parallel. A voltage detector VT1 and a link capacitor Clink are connected in parallel between both terminals of the first and second diode legs connected in parallel. The voltage detector VT1 detects the output voltage of the rectifier circuit composed of the diodes D21 to D24 and outputs the detected voltage value to the charge control device 105.

The first converter 107 configured as described above receives the output voltage of the AC-DC converter 106, switches the switching elements Q1 to Q4 connected in a bridge with an ON / OFF ratio of about 50%, and the resonant reactor Lr1. A resonance current is passed through the primary side of the resonance capacitor Cr1 and the transformer T1. By flowing current to the primary side of the transformer T1, the current generated on the secondary side of the transformer T1 is full-wave rectified by the bridge-connected diodes D21 to D24, smoothed by the link capacitor Clink, and DC voltage Outputs Vlink. That is, the first converter 107 is an isolated resonance converter, and the first converter 107 fixes the duty ratio of the gate signal applied to the switching elements Q1 to Q4 to about 50% and changes the switching frequency to change the output voltage. Take control. Specifically, the charging control device 105 outputs power corresponding to the charging power command value Pchg1 * by controlling the switching elements Q1 to Q4 based on a charging power command value Pchg1 * described later. Note that a current detector CT1 for detecting a current that is full-wave rectified by the diodes D21 to D24 is provided. The current detector CT1 outputs the detected current value to the charge control device 105.

The second converter 108 is a power converter that steps down the DC voltage Vlink output from the first converter 107 and outputs a DC voltage. The DC voltage Vlink is applied to the switching elements Q5 and Q6 connected in series. Switching elements Q5 and Q6 are ON / OFF controlled by a control signal from charge control device 105. Note that anti-parallel diodes D4 and D5 are connected to the switching elements Q5 and Q6, respectively. A reactor L2 and a capacitor C2 are connected to a connection point between the switching elements Q5 and Q6, and together with the switching elements Q5 and Q6, a step-down circuit is configured. The battery 102 is charged by the output voltage of the step-down circuit. Voltage detector VT <b> 2 detects voltage Vbatt of battery 102 and outputs the detected voltage value to charge control device 105. In addition, a current detector CT2 that detects the current of the battery 102 is provided. The current detector CT <b> 2 outputs the detected current value to the charging control device 105.

The second converter 108 configured in this way performs switching operation by controlling the switching elements Q5 and Q6 to turn on and off, and makes the output voltage of the first converter 107 rectangular. The rectangular wave voltage is smoothed by the reactor L2 and the capacitor C2, and a DC voltage is output. In addition, the input voltage of the second converter 108 and the output voltage of the second converter 108 can be made substantially equal by fixing the switching element Q5 to ON and fixing the switching element Q6 to OFF.

The charging control device 105 receives the charging power command value Pchg *, the charging current limit value Ichglim *, and the charging voltage command value Vchg * from the vehicle ECU 103, and operates the first converter 107 and the second converter 108. Here, the charging power command value Pchg * and the charging voltage command value Vchg * are target values for causing the charging device 104 to follow these values, and the charging current limit value Ichglim * is a battery 102, a relay, or the like. It means the maximum current value that can be passed from the viewpoint of protection.

As described above, the charging device 104 converts AC power input from the AC power supply 100 into DC power by the AC-DC converter 106, and outputs the AC-DC converter 106 to DC power by the first converter 107. Convert to The output of the first converter 107 is converted to DC power by the second converter 108 and the battery 102 is charged. The first converter 107 performs constant power control of charging power and constant voltage control of the battery voltage Vbatt, and the second converter 108 performs constant current control of charging current and constant voltage control of the link voltage Vlink.

Fig. 2 (a) and (b) are graphs showing factors that increase the link voltage. In FIG. 2A, the horizontal axis represents the battery voltage Vbatt, and the vertical axis represents power. 2A, the solid line indicates the power P1out output from the first converter 107, and the broken line indicates the power P2out output from the second converter.

The electric power P1out output from the first converter 107 is constant so as to follow the charging power command value Pchg *, whereas the electric power P2out output from the second converter 108 includes the battery voltage Vbatt and the charging current limit value Ichglim. Determined by the product of *. In other words, the power P2out output from the second converter 108 is determined by the charging current that can flow to the maximum with respect to the current battery voltage Vbatt.

As shown in FIG. 2A, when the battery voltage Vbatt is lower than VbattL, the power P2out output by the second converter 108, which is a broken line, is also low, and the power P1out output by the first converter 107, which is a solid line, A power difference ΔP occurs during Here, the maximum battery voltage VbattL at which the power difference ΔP occurs is a value obtained by dividing the charging power command value Pchg * by the charging current limit value Ichglim *. This power difference ΔP becomes surplus power Pdump of the output of the first converter 107 with respect to the output of the second converter 108, and increases the link voltage Vlink of the output of the first converter 107.

FIG. 2B shows the battery voltage Vbatt on the horizontal axis and the link voltage Vlink on the vertical axis. The rising voltage Vraise of the link voltage Vlink due to the surplus power Pdump is expressed by the following equation (1).

In this equation, Clink represents the capacitance of the link capacitor Clink, and t represents time.

As can be seen from the equation (1), when the surplus power Pdump is generated, the link voltage Vlink increases in proportion to the square root of the product of the time t and the surplus power Pdump, and thus becomes an overvoltage, and the output side of the first converter 107, There is a problem of causing a failure of a component connected to the input side of the second converter 108.

Note that the above-described problem does not occur if the first converter 107 performs constant voltage control of the link voltage Vlink and the second converter 108 performs constant power control of the charging power. However, in this embodiment, in order to increase efficiency, the switching elements Q5 and Q6 of the second converter 108 are switched in a range where the battery voltage is low, and the link voltage Vlink which is the output of the first converter 107 is stepped down to reduce the battery 102. Charge the battery. In the range where the battery voltage is high, the switching element Q5 of the second converter 108 is fixed on, the switching element Q6 is fixed off, and the output of the first converter 107 is passed through to charge the battery 102. Since there is an operation in a range where the battery voltage is high, the first converter 107 needs to perform constant power control of the charging power.

3 (a) and 3 (b) are graphs showing that an increase in link voltage is suppressed. FIG. 3A shows the battery voltage Vbatt on the horizontal axis and the power on the vertical axis. In FIG. 3 (a), the solid line indicates the power P1out output from the first converter 107, and the broken line indicates the power P2out output from the second converter 108. FIG. 3B shows the battery voltage Vbatt on the horizontal axis and the link voltage Vlink on the vertical axis.

As shown in FIG. 3A, when the battery voltage Vbatt is equal to or lower than VbattL, the power P1out of the first converter is represented by a dotted line in FIG. 2 (indicated by a dotted line) so that the power difference ΔP (surplus power Pdump) does not occur. The value is reduced as indicated by the solid line from the value of a), and the power P2out of the second converter indicated by the broken line is followed. By suppressing the surplus power Pdump in this way, as shown in FIG. 3B, the rise of the link voltage Vlink is suppressed, and the link voltage Vlink is changed from the original state of FIG. 2B shown by the dotted line to the solid line. As shown, it can be reduced to follow the link voltage Vlink *. Thereby, the charging apparatus 104 can be continuously operated safely.

Thus, it is necessary to reduce the surplus power Pdump in order to prevent the link voltage Vlink from rising. In order to reduce the surplus power Pdump, it is necessary to reduce the power P1out output from the first converter 107 to a predetermined power or increase the power P2out output from the second converter 108 to a predetermined power. In order to increase the electric power P2out output from the second converter 108, it is necessary to increase the battery voltage Vbatt and the charging current limit value Ichglim *. However, it is impossible to increase the battery voltage Vbatt suddenly during charging. The charging current limit value Ichglim * cannot be increased from the viewpoint of protection. Therefore, in this embodiment, the surplus power Pdump is reduced by reducing the power P1out output from the first converter 107.

In the present embodiment, as shown in FIG. 3A, when the battery voltage Vbatt is less than VbattL that generates surplus power Pdump, the power P1out output from the first converter 107 is changed from a state indicated by a dotted line to a state indicated by a solid line. Thus, the charge control device 105 controls the power command value to the first converter 107. Thereby, the electric power P1out output from the first converter 107 follows the electric power P2out output from the second converter 108. As a result, as shown in FIG. 3B, the rise of the link voltage Vlink can be suppressed so as to change from the state indicated by the dotted line to the state indicated by the solid line.

Next, a specific method of link voltage suppression control for causing the link voltage Vlink to follow a predetermined link voltage Vlink * will be described with reference to FIG.
FIG. 4 is a diagram illustrating control of the charging control device 105 by functional blocks.

The link voltage suppression control unit 301 includes an FF control unit 302 and an FB control unit 303. The FF control unit 302 calculates the power that can be output from the second converter 108 that is equivalent to the power that can be output from the first converter 107. The electric power that can be output from the second converter 108 is obtained by integrating the battery voltage Vbatt detected by the voltage detector VT2 (see FIG. 1) and the charging current limit value Ichglim * by the integrator 304 and calculating the value Pchglink__ff.

The FB control unit 303 obtains the power of the first converter 107 to be reduced with respect to the increase of the link voltage Vlink. An adder / subtractor 306 obtains a deviation between the link voltage command value Vlink * and the link voltage Vlink detected by the voltage detector VT1 (see FIG. 1). This deviation is calculated by the PI controller 307, converted into the amount of power to be reduced, and the power Plink_fb to be reduced is obtained.

The link voltage suppression control amount Pchglink is obtained by subtracting the power Plink_fb to be reduced obtained by the FB control unit 302 by the adder / subtractor 305 from the outputtable power Pchglink_ff obtained by the FF control unit 302.

The electric power correction control unit 311 calculates electric power to compensate for the shortage of the charging power Pchg output from the charging device 104 with respect to the charging power command value Pchg * given from the vehicle ECU 103. Charging power Pchg output from charging device 104 is obtained from the product of battery voltage Vbatt detected by voltage detector VT2 (see FIG. 1) and charging current Ichg detected by current detector CT2 (see FIG. 1). .

Next, the charging power Pchg is subtracted from the charging power command value Pchg * given from the vehicle ECU 103 by the adder / subtractor 313 to obtain a deviation. The obtained deviation is converted into electric power by the PI controller 314, and the upper / lower limiter 315 performs the upper limit with the maximum power loss of the second converter 108 and the lower limit with 0 to obtain the power correction amount Pcomp. The charge power command value Pchg2 * is obtained by adding the power correction amount Pcomp to the charge power command value Pchg * using the adder / subtractor 316. Then, the upper and lower limiter 308 limits the charging power command value Pchg2 * to the upper limit based on the link voltage suppression control amount Pchglink determined by the link voltage suppression control unit 301, and determines the final charging power command value Pchg1 *.

The charge power command value Pchg1 * subjected to link voltage suppression is when the link voltage suppression control does not work, that is, when the battery voltage Vbatt and the charge current limit value Ichglim * are equal to or greater than the charge power command value Pchg * provided from the vehicle ECU 103. The charging power command value Pchg * given from the vehicle ECU 103 is obtained. On the other hand, when the battery voltage Vbatt and the charging current limit value Ichglim * are less than the charging power command value Pchg * given from the vehicle ECU 103, the charging power command value Pchg1 * subjected to link voltage suppression is received by the link voltage suppression control unit 301. The obtained value Pchg1 * is obtained.

The charging control device 105 controls the switching elements Q1 to Q4 of the first converter 107 based on the charging power command value Pchg1 *. Thereby, the first converter 107 outputs power corresponding to the charging power command value Pchg1 *. As a result, as shown in FIG. 3A, when the battery voltage Vbatt is less than VbattL that generates surplus power Pdump, the power P1out output from the first converter 107 changes from the state indicated by the dotted line to the state indicated by the solid line. The power command value to the first converter 107 is controlled. And as shown in FIG.3 (b), a raise can be suppressed so that link voltage Vlink may be in the state shown with a continuous line from the state shown with a dotted line.

(Second Embodiment)
FIG. 5 is a system configuration diagram in the second embodiment. A first converter 107a is shown instead of the first converter 107 shown in FIG. 1, and the other configurations are the same as those in FIG.

Hereinafter, the first converter 107a will be described with reference to FIG. The first converter 107a converts the DC voltage into an insulated DC voltage by controlling the phase of the first arm Leg1 composed of the switching elements Q1a and Q2a and the second arm Leg2 composed of the switching elements Q3a and Q4a. To do. The ON / OFF ratio of the switching elements Q1a to Q4a is about 50%, and the ON / OFF states of the switches of the switching elements Q1a and Q2a and Q3a and Q4a are in a complementary relationship. The output of the first converter 107a is increased by increasing the time during which the switching elements Q1a and Q4a and the switching elements Q2a and Q3a are simultaneously turned ON, and the output of the first converter 107a is decreased by decreasing the ON time. .

That is, the first converter 107a switches the switching elements Q1a to Q4a with respect to the input voltage Vin, thereby causing a current to flow on the primary side of the transformer T1a and generating a current on the secondary side of T1a. The current generated on the secondary side of the transformer T1a is full-wave rectified by the bridge-connected diodes D21a to D24a, and smoothed by the reactor L1a and the capacitor Clinka to generate the output voltage Vout.

The first converter 107 in the first embodiment shown in FIG. 1 may have poor control characteristics because the relationship between the switching frequency and the input / output ratio of the first converter 107 is non-linear. For example, this is the case when the output voltage is lowered at light load. On the other hand, the first converter 107a in the second embodiment shown in FIG. 5 fixes the switching frequency of the gate signal applied to the switching elements Q1a to Q4a to an arbitrary frequency, and sets the duty ratio of the switching period of the switching element. The output is controlled by changing it. In this duty control, since the relationship between the duty ratio and the input / output ratio of the first converter 107a is linear, the control characteristics are good.

In addition, the switching frequency of the gate signal applied to the switching elements Q1a to Q4a is fixed to an arbitrary frequency, the duty ratio is also fixed to 50%, and the output is controlled by changing the phase difference between Leg1 and Leg2 that perform complementary switching. You can also. In the phase difference control, since the relationship between the phase difference and the input / output ratio is linear, the control characteristics are good.

According to the embodiment described above, the following operational effects can be obtained.
(1) The charging device 104 converts the input power into a DC voltage and outputs it, and outputs a command value to the first converter 107 to control the power on the output side of the first converter 107. And a second converter 108 that steps down a DC voltage on the output side of the first converter 107 and supplies the DC voltage to the battery 102. The charge control device 105 includes a voltage on the output side of the first converter 107. The first converter 107 is controlled by outputting a command value so that the voltage drops to a predetermined voltage. Thereby, the charging device which charges with high efficiency can be provided.

(2) The charging control device 105 controls the first converter 107 by outputting a command value so that the power output from the first converter 107 follows the power output from the second converter 108. Thereby, the rise in the voltage output from the first converter 107 can be suppressed.

(3) When the current output from the second converter is a predetermined charging current limit value and the voltage output from the second converter 108 is equal to or lower than the predetermined output voltage, the charging control device 105 A command value is output to control the first converter 107 so that the voltage on the output side of the converter 107 drops to a predetermined voltage. As a result, it is possible to suppress an increase in voltage output from the first converter 107 when the battery voltage is low.

(4) Based on the command value, the first converter 107a changes the duty ratio of the switching period of the switching elements constituting the first converter 107a to lower the output voltage to a predetermined voltage. Thereby, the voltage output from the first converter 107a can be controlled.

(5) The first converter 107a is composed of a first arm Leg1 and a second arm Leg2 made of bridge-connected switching elements, and changes the phase difference between the first arm Leg1 and the second arm Leg2 based on the command value. Then, the output side voltage is lowered to a predetermined voltage. Thereby, the voltage output from the first converter 107a can be controlled.

The present invention is not limited to the above-described embodiment, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention as long as the characteristics of the present invention are not impaired. .

100 AC power source 101 Electric vehicle 102 Battery 103 Vehicle ECU
104 Charging Device 105 Charging Control Device 106 AC-DC Converter 107 First Converter 108 Second Converter

Claims

A first converter that converts the input power into a DC voltage and outputs the DC voltage;
A control unit that outputs a command value to the first converter and controls electric power on an output side of the first converter;
A second converter for stepping down the DC voltage on the output side of the first converter and supplying it to the battery,
The control unit is a charging device that outputs the command value and controls the first converter so that a voltage on an output side of the first converter is lowered to a predetermined voltage.
The charging device according to claim 1,
The control unit outputs the command value to control the first converter so that the power output from the first converter follows the power output from the second converter.
The charging device according to claim 1 or 2,
When the current output from the second converter is a predetermined charging current limit value and the voltage output from the second converter is equal to or lower than a predetermined output voltage, the control unit A charging device that controls the first converter by outputting the command value so that a voltage on an output side drops to the predetermined voltage.
The charging device according to claim 3,
The first converter is a charging device that changes a duty ratio of a switching period of a switching element that constitutes the first converter based on the command value to lower an output-side voltage to the predetermined voltage.
The charging device according to claim 3,
The first converter is composed of a first arm and a second arm made of bridge-connected switching elements, and changes the phase difference between the first arm and the second arm based on the command value to output the first converter A charging device that reduces the voltage of the battery to the predetermined voltage.