JP7167843B2 - car charger - Google Patents

Description

The present invention relates to an in-vehicle charger.

An in-vehicle charger that charges an in-vehicle battery from an AC power supply uses a configuration in which charging is performed from an AC power supply via a power factor correction (PFC) circuit (hereinafter referred to as a PFC circuit) and a converter circuit. .

A temperature sensor is provided in each of the converter circuit and the PFC circuit to detect the temperature of the circuit during the charging operation. The temperature sensor is configured to detect temperature by providing a resistance element having a temperature coefficient, such as a thermistor, and to stop the charging operation when a temperature abnormality is detected.

In this case, it is known that the temperature sensors of the PFC circuit and the converter circuit have a certain degree of correlation in how the temperature changes during the charging operation. By using this, the magnitude relationship between the temperatures detected by both temperature sensors and the correlation between temperature changes are stored in advance. It is determined to be faulty.

However, in the configuration described above, although it is possible to determine that the temperature sensor is malfunctioning due to an abnormality, it does not change whether the malfunctioning temperature sensor is in the PFC circuit or in the converter circuit.・Short-circuit/disconnection mode anomalies are judged, but other anomalies caused by changes in characteristics due to aged deterioration of materials, for example, are not individually judged. Therefore, when an abnormality other than the permanent/short-circuit/disconnection mode has occurred, it has been impossible to identify the temperature sensor that has failed.

Therefore, in an on-vehicle charger that is configured to charge the on-vehicle battery not only from an AC power supply but also from a DC power supply from the input section of the converter circuit, when adopting the above configuration, the temperature If the faulty part of the sensor could not be identified, either charging would be unusable.

Japanese Patent No. 5569969

The present invention has been made in consideration of the above circumstances, and its object is to provide a configuration in which a plurality of temperature sensors are provided, and when an abnormality is detected in a temperature sensor, it is possible to reliably determine whether the temperature sensor is on the PFC side or the converter side. To provide an in-vehicle charger capable of determining.

The vehicle-mounted charger according to claim 1 charges the vehicle-mounted battery with the AC input voltage from the AC input section through the power factor improvement section (20) and the converter section (40), and the DC input voltage of the converter section. A vehicle-mounted charger for charging the vehicle-mounted battery from a DC input section, wherein the power factor correction section includes a full-wave rectifier circuit (21) for converting the AC input voltage into a DC output, and a DC output of the full-wave rectifier circuit. a power factor correction circuit (22) for improving the power factor of the output by a coil (26) and a switching element (27) and charging a smoothing capacitor (25); an inverter circuit (41) for converting into an AC voltage; and an output circuit (42) for rectifying and smoothing the AC voltage of the inverter circuit and supplying it to the onboard battery. A first temperature sensor (28) and a second temperature sensor (43) provided to detect temperature detect a zero-cross period in which the AC input voltage is near zero-cross, and turn on/off the switching element during the zero-cross period. A detection circuit (31) for driving and detecting the switching time at that time detects the temperature from the detection signals of the first and second temperature sensors, and when the correlation between the detection signals deviates from a predetermined range. and a control circuit (29) for detecting a failure state of one of the first and second temperature sensors and estimating the temperature of the switching element from the switching time from the detection circuit. The control circuit determines which of the first and second temperature sensors is in the failure state based on the temperature of the switching element estimated from the switching time of the switching element in the zero-cross period.

By adopting the above configuration, the detection circuit detects a zero-cross period in which the AC input voltage is close to zero-cross, drives the switching element on and off during the detected zero-cross period, and detects the switching time at that time. The control circuit detects temperature from detection signals of the first and second temperature sensors, and detects a failure state of either the first or second temperature sensor when the correlation between the detection signals deviates from a predetermined range. do. Since the control circuit estimates the temperature of the switching element based on the switching time from the detection circuit, it can be determined which of the first and second temperature sensors has failed.

As a result, when it can be determined that the first temperature sensor is out of order, the charging operation can be performed during charging by DC input in which the charging operation is performed without using the first temperature sensor. Even in such a case, charging can be performed.

Electrical configuration diagram showing one embodiment Electrical configuration diagram of detection circuit Diagram showing the flow of temperature detection processing Timing chart 1 Timing chart 2 Timing chart 3 Electrical configuration diagram for explaining the principle of operation Action diagram

An embodiment will be described below with reference to FIGS. 1 to 8. FIG.
In FIG. 1, an onboard charger 10 for charging an onboard battery 100 includes an AC input plug 200 from a commercial power source and a DC input plug 300 for rapid charging from a DC power source. In-vehicle charger 10 includes PFC section 20 and converter section 40 .

The PFC section 20 includes a full-wave rectifier circuit 21 , a power factor correction circuit 22 and a control section 23 . The full-wave rectifier circuit 21 is configured by a diode bridge circuit, and outputs a DC output Vdc obtained by full-wave rectifying the AC voltage Vac input from the AC input plug 200 to the power factor correction circuit 22 .

The power factor correction circuit 22 improves the power factor of the DC output Vdc of the full-wave rectifier circuit 21 and charges the smoothing capacitor 25 through the diode 24 . The power factor is improved by driving and controlling the primary coil of the transformer 26 and the MOS transistor 27 as a switching element to boost the voltage. A first temperature sensor 28 consisting of a thermistor is arranged near the MOS transistor 27 to detect the temperature of the PFC section 20 .

The control unit 23 includes a microcomputer 29 as a control circuit, a drive circuit 30, a detection circuit 31, and the like. The drive circuit 30 applies a drive voltage Vdrv to the gate of the MOS transistor 27 through the resistor 32 to turn it on and off. A current flowing through the primary coil of the transformer 26 is detected by a resistor 33 connected across the secondary coil. A voltage drop occurs across the resistor 33 due to the current flowing through the secondary coil of the transformer 26, and the microcomputer 29 detects this voltage drop as a voltage Vsense.

The detection circuit 31 takes in the gate voltage Vgs of the MOS transistor 27 and the drive voltage Vdrv and voltage Vsense of the drive circuit 30, detects the zero-cross period and the switching time of the MOS transistor 27, and outputs detection signals Szc and Ssw to the microcomputer 29. . The microcomputer 29 receives the detection signal of the first temperature sensor 28 as well as the detection signal of the second temperature sensor 43, which will be described later. A display unit 34 is connected to the microcomputer 29, and a display signal is output to the display unit 34 to turn on a lamp or output a display to a display element, thereby enabling AC charging or DC charging to the user. let you know what

The converter section 40 includes an inverter circuit 41 and an output circuit 42 . The inverter circuit 41 is formed by connecting four MOS transistors 41 a to 41 d as switching elements in a bridge connection, and converts the DC voltage output from the PFC unit 20 into a predetermined AC voltage and outputs the AC voltage to the output circuit 42 . The inverter circuit 41 is also connected to a DC input plug 300 for rapid charging, and receives a DC voltage. A second temperature sensor 43 made up of a thermistor is arranged near the MOS transistor 41b so as to detect the temperature of the converter section 40 .

The output circuit 42 includes an insulating transformer 44 , a full-wave rectifier circuit 45 , a coil 46 and a capacitor 47 . The AC output of the inverter circuit 41 is input to the full-wave rectifier circuit 45 via the transformer 44 . A full-wave rectifier circuit 45 smoothes the full-wave rectified DC output with a coil 46 and a capacitor 47 . The in-vehicle battery 100 charges from both terminals of the capacitor 47 .

As shown in FIG. 2, the detection circuit 31 includes a comparator 31a, a flip-flop 31b, an inverter 31c, a comparator 31d, an AND circuit 31e, and a counter 31f. The comparator 31a has an inverting input terminal to which the voltage Vsense is input, and a non-inverting input terminal to which the reference voltage Vref is input. The reference voltage Vref is for determining the zero-cross period, and is set to a voltage slightly higher than 0V.

The output terminal of the comparator 31a is connected to the set terminal S of the flip-flop 31b. A drive voltage Vdrv is input to the reset terminal R of the flip-flop 31b. The output terminal Q of the flip-flop 31b outputs the output signal inverted through the inverter 31c as the zero-cross signal Szc.

The comparator 31d has an inverting input terminal to which the comparison voltage Vcomp is input, and a non-inverting input terminal to which the gate voltage Vgs is input. The comparison voltage Vcomp is a voltage set for detecting the switching time Tsw until the gate voltage Vgs attenuates to approximately 0V. The output terminal of the comparator 32d is connected to one input terminal of the AND circuit 31e. An inverted signal of the drive voltage Vdrv is input to the other input terminal of the AND circuit 31e.

The output terminal of the AND circuit 31e is connected to the input terminal EN of the counter 31f. A clock signal CLK is input to the clock terminal CLK of the counter 31f. The counter 31f counts up the clock signal CLK and outputs it from the output terminal as the count signal Stc while the input signal of the input terminal EN is at high level.

Next, the operation of the above configuration will be described with reference to FIGS. 3 to 8 as well.
In the vehicle charger 10 , when the vehicle battery 100 is charged from a commercial AC power source, the AC voltage Vac is input from the AC input plug 200 to the full-wave rectifier circuit 21 of the PFC section 20 . The AC voltage Vac is full-wave rectified by the full-wave rectifier circuit 21 and input to the power factor correction circuit 22 as a pulsating DC voltage Vdc. At this time, the microcomputer 29 supplies a drive signal to the drive circuit 30 to drive the MOS transistor 27 of the power factor improvement circuit 22 with the ON/OFF drive voltage Vdrv, and charges the smoothing capacitor 25 while improving the power factor.

The converter unit 40 takes in the DC voltage of the smoothing capacitor 25 of the PFC unit 20, adjusts it so as to correspond to the voltage of the vehicle battery 100, and outputs it. First, the MOS transistors 41 a to 41 d of the inverter circuit 41 are driven and controlled to convert to a predetermined AC voltage, which is then DC-converted by the full-wave rectifier circuit through the transformer 44 and output to the capacitor 47 through the coil 46 . As a result, the charging operation is performed in a state in which the voltage is converted to a DC voltage corresponding to the on-vehicle battery 100 .

While executing the above operation, microcomputer 29 receives temperature detection signals from first temperature sensor 28 and second temperature sensor 43 and monitors the temperatures of PFC section 20 and converter section 40 . By continuing the charging operation, the temperatures of PFC unit 20 and converter unit 40 gradually rise. At this time, since the PFC section 20 and the converter section 40 are operating in the same manner, the tendencies of the temperature rise are correlated with each other. Using this, the process of estimating the temperatures of the first temperature sensor 28 and the second temperature sensor 43 is executed.

Also, in case one of the first temperature sensor 28 and the second temperature sensor 43 fails, the microcomputer 29 detects the temperature of the MOS transistor 27, which is a switching element, based on a different detection principle. . This detection principle and actual operation will be described below.

First, the detection of the switching time when the MOS transistor 27 is on or off will be described. FIG. 7 shows a model corresponding to the MOS transistor 27 portion of this embodiment. A coil L corresponding to the primary coil of the transformer 26 and a MOS transistor Tr corresponding to the MOS transistor 27 are connected in series between the power supply voltage VDD and the ground.

Next, in FIG. 8, when the switching operation is performed with the voltage VDS applied between the drain and source of the MOS transistor Tr, a mirror period occurs in the waveform of the gate voltage Vgs. The length of this mirror period changes depending on the magnitude of the voltage VDS and the drain current ID. This is because the MOS transistor Tr has parasitic capacitances Cgs, Cgd, and Cds between terminals.

Since the parasitic capacitance Cgs between the gate and the source is dominant among them, the operation of turning off the gate is the operation of drawing out electric charges from the parasitic capacitance Cgs. In this electric charge extraction operation, when the gate voltage Vgs decreases, the drain-source voltage VDS begins to rise (t1), causing a displacement current iG=Cgd·(dVDS/dt) to flow from the drain to the gate. Become.

Therefore, the extraction of charges from the parasitic capacitance Cgs is hindered, and a mirror period occurs during which the gate voltage Vgs does not decrease. This mirror period continues until VDS reaches the power supply voltage VDD (t2). In addition, the length of the mirror period depends on dV/dt, which in turn depends on VDD, and also on the current value ID, so that the switching speed of the gate changes greatly during the operation of the PFC.

On the other hand, when the voltage VDS is not applied between the drain and source of the MOS transistor Tr, as shown in FIG. The switching time can be detected by measuring the time until the voltage drops to Vth.

Further, since it is known that the parasitic capacitance Cgs between the gate and the source has temperature dependence, it is possible to refer to preset correlation data by measuring the rise time or fall time of the gate voltage Vgs. , the temperature of the MOS transistor 27 can be estimated.

Therefore, in the present embodiment, the detection circuit 31 detects a period in which no voltage is applied between the drain and source of the MOS transistor 27 as the zero-cross period, and the microcomputer 29 determines the switching time Tsw of the MOS transistor 27 during the zero-cross period. It is configured to measure and estimate the temperature.

Specifically, as shown in FIG. 4, when the sinusoidal AC input Vac is full-wave rectified by the full-wave rectifier circuit 29, a voltage drop in the forward voltage Vf of the diode causes a zero-cross period Tzc. . Specifically, for example, at AC 200 V at 60 Hz, a zero-cross period Tzc of about 20 us during which the DC voltage Vdc becomes 0 V occurs before and after the zero-cross tz. Since this period Tzc is a period in which the voltage VDS is not applied between the drain and source of the MOS transistor 27, it can be used to detect the switching time.

As shown in FIG. 4, during the zero-cross period Tzc between times tza and tzb, no current flows through the MOS transistor 27, so Vsense is also zero. Since the driving voltage Vdrv is applied from the driving circuit 30 to the gate of the MOS transistor 27 during the zero-cross period Tzc as well, the time from the time t0 when the MOS transistor 27 is turned off until the gate voltage Vgs of the MOS transistor 27 becomes equal to or lower than the predetermined level Vcomp is Measure.

Next, operation of the detection circuit 31 will be described. As shown in FIG. 5, the comparator 31a outputs a high-level signal S1 when Vsense, which is the signal of the current ID of the MOS transistor 27, is equal to or lower than the reference voltage Vref at which it is almost zero. When the signal S1 is at high level, the flip-flop 31b and the inverter 31c detect the timing at which the drive voltage Vdrv turns on, that is, the period during which no current flows due to the drive voltage Vdrv, as the zero-cross signal Szc. The period from time t1 to t2 in which the zero-cross signal Szc is high level is the zero-cross period Tzc.

In addition, the detection circuit 31 measures the switching time at the timing when the drive voltage Vdrv is turned off while the zero-cross signal Szc shown in FIG. 5 is at the high level. As shown in FIG. 6, when the drive voltage Vdrv becomes low level at time t0, the gate voltage Vgs of the MOS transistor 27 gradually decreases because the parasitic capacitance Cgs is discharged through the resistor 32. FIG.

The output signal S2 of the comparator 31d is at high level when the gate voltage Vgs is equal to or higher than Vcomp for determining zero level. In the AND circuit 31e, the output signal S3 is at high level during the period from time t0 to t1 when the drive voltage Vdrv is at low level and the output signal S2 at high level is input from the comparator 31d. The period during which the output signal S3 is high level corresponds to the switching time during which the MOS transistor 27 is turned off.

The counter circuit 31f outputs a count signal Ssw obtained by counting up the high level period of the signal S3 from the AND circuit 31e based on the clock signal CLK. The count value of the count signal Ssw, that is, the peak value corresponds to the switching time Tsw. As a result, the microcomputer 29 receives the zero-cross signal Szc and the count signal Ssw from the detection circuit 31 .

The microcomputer 29 performs temperature detection processing by the first temperature sensor 28 and the second temperature sensor 43 according to the flow shown in FIG. determine the fault. Further, when one of the first and second temperature sensors 28 and 43 fails, the microcomputer 29 detects the pre-stored switching time Tsw and The temperature is estimated from the element temperature correlation data. Furthermore, if there is a discrepancy between the estimated temperature and the temperature measured by the first temperature sensor 28, it is determined that the first temperature sensor 28 has failed.

The microcomputer 29 repeatedly executes the temperature detection process shown in FIG. 3 at appropriate timings. In FIG. 3, the microcomputer 29 first performs temperature detection by the first temperature sensor 28 and the second temperature sensor 43 in step S101. In this process, the microcomputer 29 detects the temperature based on the detection signals detected by the first temperature sensor 28 and the second temperature sensor 43 and based on pre-stored correlation data between the temperature and the detection signals.

Next, in step S102, the microcomputer 29 determines whether the temperature difference ΔT detected by the first temperature sensor 28 and the second temperature sensor 43 is within a predetermined range. In a state in which vehicle battery 100 is being charged by an AC input, both PFC unit 20 and converter unit 40 operate, and a current flows between the first temperature sensor 28 and second temperature sensor 43 . have a certain correlation. As for the correlation between the temperature sensors, the temperature rise manner and the temperature difference data between the two are stored in advance.

If the temperature difference ΔT detected by the first temperature sensor 28 and the second temperature sensor 43 is within a predetermined range, the microcomputer 29 determines YES, indicating that the temperature is being detected normally and that an abnormal temperature is detected. The temperature detection process is terminated assuming that the temperature has not been detected.

On the other hand, if the temperature difference ΔT detected by the first temperature sensor 28 and the second temperature sensor 43 is out of the predetermined range, the microcomputer 29 determines NO, and then proceeds to step S103. In this case, the fact that the detected temperature difference ΔT is out of the predetermined range means that either one of the first temperature sensor 28 and the second temperature sensor 43 is out of order because it is rare for the first temperature sensor 28 and the second temperature sensor 43 to fail at the same time. can be estimated.

In step S103, the microcomputer 29 performs processing for estimating the temperature of the MOS transistor 27, that is, the temperature of the PFC section 20, from the data of the switching time Tsw. Since the temperature to be estimated at this time is obtained independently of the temperature detected by the first temperature sensor 28, there is a correlation with the estimated temperature when the first temperature sensor 28 normally detects the temperature. should be.

Next, in step S104, the microcomputer 29 determines whether or not there is a correlation between the temperature of the PFC section 20 estimated from the switching time Tsw and the temperature detected by the first temperature sensor . Here, if NO, that is, if there is no correlation, the microcomputer 29 proceeds to step S105 and determines that the first temperature sensor 28 is abnormal.

In this case, since the temperature of the PFC unit 20 cannot be detected by the first temperature sensor 28, the microcomputer 29 prohibits AC input charging using the PFC unit 20 in step S106. causes the user to display that charging by AC input is prohibited, and terminates the temperature detection process.

Since it is determined that the first temperature sensor 28 has failed, the second temperature sensor 43 is still usable. It is also possible to display on the display section 34 that rapid charging by DC voltage is possible.

On the other hand, if YES in step S104, that is, if there is a correlation, the microcomputer 29 proceeds to step S107 and determines that the second temperature sensor 43 is abnormal.

In this case, since the second temperature sensor 43 cannot detect the temperature of the converter unit 40, the microcomputer 29 prohibits both AC input and DC input charging using the converter unit 40 in step S106. Further, the display unit 34 displays to the user that charging by AC input and charging by DC input are prohibited, and the temperature detection process is terminated.

In this embodiment, in addition to the temperature detection by the first temperature sensor 28 and the second temperature sensor 43, the temperature of the PFC unit 20 is separately detected by the switching time of the MOS transistor 27 of the control circuit PFC unit 20. , the first temperature sensor 28 and the second temperature sensor 43 can be identified.

As a result, when the first temperature sensor 28 fails, charging by AC input is disabled, but since the second temperature sensor 43 is normal, it is possible to charge the on-vehicle battery by DC input. It becomes possible to notify the user of something.

(Other embodiments)
The present invention is not limited to the above-described embodiments, and can be applied to various embodiments without departing from the scope of the invention. For example, the following modifications or extensions can be made.

In the above-described embodiment, when it is identified that the first temperature sensor 28 is out of order, the PFC unit 20 is disabled from temperature detection by the first temperature sensor 28, thereby prohibiting the charging operation by the AC input. However, when the second temperature sensor 43 is normal and the temperature detection operation of the PFC unit 20 can be continued by detecting the switching time Tsw of the MOS transistor 27, charging by AC input is permitted. is also possible.

Although the present disclosure has been described with reference to examples, it is understood that the present disclosure is not limited to such examples or structures. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and configurations, as well as other combinations and configurations, including single elements, more, or less, are within the scope and spirit of this disclosure.

In the drawings, 10 is an onboard charger, 20 is a PFC section, 21 is a full wave rectifier circuit, 22 is a power factor correction circuit, 23 is a control section, 25 is a smoothing capacitor, 26 is a transformer (coil), and 27 is a MOS transistor ( 28 is a first temperature sensor; 29 is a microcomputer (control circuit); 30 is a drive circuit; 31 is a detection circuit; is a second temperature sensor, 100 is a vehicle-mounted battery, 200 is an AC input plug, and 300 is a DC input plug.

Claims (5)

An in-vehicle vehicle that charges an onboard battery with an AC input voltage from an AC input unit via a power factor correction unit (20) and a converter unit (40), and charges the onboard battery with a DC input voltage from a DC input unit of the converter unit. a charger,
The power factor improvement unit
a full-wave rectifier circuit (21) for converting the AC input voltage into a DC output;
a power factor correction circuit (22) for improving the power factor of the DC output of the full-wave rectification circuit by means of a coil (26) and a switching element (27) and charging a smoothing capacitor (25);
The converter section
an inverter circuit (41) for converting the DC voltage of the smoothing capacitor into an AC voltage;
an output circuit (42) for rectifying and smoothing the AC voltage of the inverter circuit and supplying it to the vehicle battery;
a first temperature sensor (28) and a second temperature sensor (43) arranged to detect respective temperatures of the power factor correction section and the converter section;
a detection circuit (31) for detecting a zero-cross period in which the AC input voltage is in the vicinity of zero-cross, driving the switching element on and off during the zero-cross period, and detecting a switching time at that time;
temperature detection from the detection signals of the first and second temperature sensors, and detecting a failure state of either the first or second temperature sensors when the correlation between the detection signals deviates from a predetermined range; a control circuit (29) for estimating the temperature of the switching element from the switching time from the detection circuit ;
The control circuit determines, based on the temperature of the switching element estimated from the switching time of the switching element in the zero-cross period, which of the first and second temperature sensors is in the failure state. charger. As a result of determining which one of the first and second temperature sensors is in the failure state, the control circuit outputs the DC input voltage to the converter section if the first temperature sensor is in failure. 2. The on-vehicle charger of claim 1, wherein the on-vehicle battery is charged from the DC input of the . The vehicle-mounted charger according to claim 1 or 2, wherein the detection circuit detects a period during which the AC input voltage is equal to or lower than a forward voltage of a diode constituting the full-wave rectifier circuit as a zero-cross period . The control circuit drives and controls the switching element by PWM control,
The vehicle-mounted charger according to any one of claims 1 to 3, wherein the detection circuit monitors the current of the switching element and detects a cycle in which no current flows as a zero-cross period . The vehicle-mounted charger according to any one of claims 1 to 4, wherein the control circuit stores therein correlation data between the temperature of the switching element and the switching time .

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