Power circuit

Abstract

To provide a power supply circuit that can detect abnormalities in multiple DC-DC converters without increasing the overall circuit size, including the abnormality detection function. [Solution] The power supply circuit according to the embodiment comprises a plurality of DC-DC converters, a plurality of detection circuits, and a determination circuit. The plurality of DC-DC converters are connected in parallel to the load. The plurality of detection circuits are provided for each of the plurality of DC-DC converters and detect the output current of each of the plurality of DC-DC converters. The determination circuit is provided for any of the plurality of DC-DC converters and compares the output currents detected by the plurality of detection circuits and determines an abnormality in the plurality of DC-DC converters based on the comparison result.

Description

Technical Field

[0001] The present invention relates to a power supply circuit.

Background Art

[0002] Conventionally, in a power supply circuit that controls power supply to a load, in order to cope with the output of a large current, a multi-phase control in which a plurality of DCDC converters are connected in parallel and controlled is known (for example, see Patent Document 1). Further, Patent Document 1 discloses a technique in which a detection circuit for detecting an overcurrent is provided in each DCDC converter, the output of each detection circuit is input to an abnormality detection device, and the abnormality of each DCDC converter is detected by the abnormality detection device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the prior art, since it is necessary to separately provide a dedicated abnormality detection device, there is a risk that the circuit size of the power supply circuit will become large.

[0005] The present invention has been made in view of the above, and an object thereof is to provide a power supply circuit that can detect abnormalities in a plurality of DCDC converters without increasing the circuit size as a whole including an abnormality detection function.

Means for Solving the Problems

[0006] To solve the above-mentioned problems and achieve the objective, the power supply circuit according to the present invention comprises a plurality of DC-DC converters, a plurality of detection circuits, and a determination circuit. The plurality of DC-DC converters are connected in parallel to the load. The plurality of detection circuits are provided for each of the plurality of DC-DC converters and detect the output current of each of the plurality of DC-DC converters. The determination circuit is provided for any of the plurality of DC-DC converters and compares the output currents detected by the plurality of detection circuits and determines an abnormality in the plurality of DC-DC converters based on the comparison result. [Effects of the Invention]

[0007] According to the present invention, a determination circuit is provided in one of the multiple DC-DC converters, and the determination circuit detects abnormalities in the multiple DC-DC converters. In other words, in the present invention, by equipping the abnormality detection function in one of the DC-DC converters, a dedicated abnormality detection device is not required, and abnormalities in multiple DC-DC converters can be detected without increasing the overall circuit size, including the abnormality detection function. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows an example of the configuration of a power supply circuit according to an embodiment. [Figure 2] Figure 2 shows the circuit configuration of the first switch section. [Modes for carrying out the invention]

[0009] The power supply circuit according to the embodiment will be described in detail below with reference to the attached drawings. However, the present invention is not limited to the embodiments shown below.

[0010] First, the configuration and operation of the power supply circuit according to the embodiment will be described using Figure 1. Figure 1 is a diagram showing an example of the configuration of the power supply circuit according to the embodiment. The power supply circuit 1 shown in Figure 1 is a power supply circuit that performs multiphase control. In this disclosure, an example of performing multiphase control with two DC-DC converters is shown, but it may also be possible to perform multiphase control with three or more DC-DC converters.

[0011] Specifically, the power supply circuit 1 consists of a first DC-DC converter 10 and a second DC-DC converter 20 connected in parallel to a load (not shown). The load is connected to the output voltage Vout shown in Figure 1.

[0012] The first DC-DC converter 10 comprises a first switch unit 11, a coil 12, a detection resistor 13, and a capacitor 14. The first switch unit 11, the coil 12, the detection resistor 13, and the capacitor 14 are connected in series toward the load (output voltage Vout) in that order. The first switch unit 11 is also connected across the detection resistor 13.

[0013] The first switch unit 11 includes a switching element (not shown) and controls the switching element using PWM (Pulse Width Modulation) to convert the input voltage input to the first switch unit 11 into a signal corresponding to the duty cycle of the PWM control and output it to the coil 12. The first switch unit 11 also includes a determination circuit 110 that determines whether or not there is a malfunction in the first DC-DC converter 10 and the second DC-DC converter 20. Details of the determination circuit 110 will be described later.

[0014] The coil 12 and capacitor 14 form a smoothing circuit that smooths the signal output from the first switch unit 11. The smoothed signal is output to the load as the output voltage Vout.

[0015] The detection resistor 13 is a detection resistor that detects the output current output from the first DC-DC converter 10 to the load. The first switch unit 11 (determination circuit 110, described later) detects the voltage across the detection resistor 13 to detect the voltage drop across the detection resistor 13 and estimates the output current of the first DC-DC converter 10 from the voltage drop. The first switch unit 11 (determination circuit 110, described later) also detects the voltage across the detection resistor 23 of the second DC-DC converter 20 to detect the voltage drop across the detection resistor 23 and estimates the output current of the second DC-DC converter 20 from the voltage drop.

[0016] The second DC-DC converter 20 comprises a second switch unit 21, a coil 22, a detection resistor 23, and a capacitor 24. The second switch unit 21, the coil 22, the detection resistor 23, and the capacitor 24 are connected in series in that order toward the load (output voltage Vout). The second switch unit 21 is also connected across the detection resistor 23.

[0017] The second switch unit 21 includes a switching element (not shown), and by controlling the switching element with PWM, it converts the input voltage input to the second switch unit 21 into a signal corresponding to the duty cycle of the PWM control and outputs it to the coil 22.

[0018] The coil 22 and capacitor 24 form a smoothing circuit that smooths the signal output from the second switch unit 21. The smoothed signal is output to the load as the output voltage Vout.

[0019] The detection resistor 23 is a detection resistor that detects the output current output from the second DC-DC converter 20 to the load. The second switch unit 21 detects the voltage across the detection resistor 23, thereby detecting the voltage drop across the detection resistor 23, and estimates the output current of the second DC-DC converter 20 from the voltage drop.

[0020] In the present disclosure, among the first DC-DC converter 10 and the second DC-DC converter 20, the determination circuit 110 is provided only in the first DC-DC converter 10. The determination circuit 110 detects an abnormality in the first DC-DC converter 10 and the second DC-DC converter 20 by detecting the output currents of the first DC-DC converter 10 and the second DC-DC converter 20 using the detection resistors 13 and 23.

[0021] As described above, according to the present disclosure, the determination circuit 110 is provided in any one of the plurality of DC-DC converters 10 and 20, and the determination circuit 110 detects an abnormality in the plurality of DC-DC converters 10 and 20. That is, in the present disclosure, by mounting the abnormality detection function in the first DC-DC converter 10, a dedicated abnormality detection device is not required, and thus an abnormality in the DC-DC converters 10 and 20 can be detected without increasing the circuit size.

[0022] Next, the circuit configuration of the first switch unit 11 will be described using FIG. 2. FIG. 2 is a diagram showing the circuit configuration of the first switch unit 11. Although FIG. 2 shows the configuration of the first switch unit 11, the second switch unit 21 has the same configuration as the first switch unit 11 except that the determination circuit 110 is not provided.

[0023] As shown in FIG. 2, the first switch unit 11 includes a determination circuit 110, a driver 116, a first switching element 117, and a second switching element 118.

[0024] The driver 116 performs switching control on the first switching element 117 and the second switching element 118 by PWM control. Specifically, the driver 116 generates a gate voltage to be applied to the gates of the first switching element 117 and the second switching element 118, respectively.

[0025] The first switching element 117 is an N-channel type MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). The first switching element 117 is a switching element located on the high-side, with its drain connected to a voltage source that supplies the input voltage Vin, and its source connected to the drain of the second switching element 118.

[0026] The second switching element 118 is an N-channel MOSFET. The second switching element 118 is a switching element located on the low-side, with its drain connected to the source of the first switching element 117 and its source connected to ground.

[0027] The determination circuit 110 includes a first differential amplifier circuit 111, a second differential amplifier circuit 112, a third differential amplifier circuit 113, a first comparator 114, and a second comparator 115.

[0028] The input terminal of the first differential amplifier circuit 111 is connected to the detection resistor 13. Specifically, the input side of the detection resistor 13 is connected to the positive terminal of the first differential amplifier circuit 111, and the output side of the detection resistor 13 is connected to the negative terminal. In addition, the output terminal of the first differential amplifier circuit 111 is connected to the input terminal of the third differential amplifier circuit 113 and the input terminal of the first comparator 114.

[0029] The first differential amplifier circuit 111 outputs a first differential signal from its output terminal, which is an amplified version of the voltage difference (i.e., voltage drop) between the input and output sides of the detection resistor 13.

[0030] The input terminal of the second differential amplifier circuit 112 is connected to the detection resistor 23. Specifically, the input side of the detection resistor 23 is connected to the positive terminal of the second differential amplifier circuit 112, and the output side of the detection resistor 23 is connected to the negative terminal. In addition, the output terminal of the second differential amplifier circuit 112 is connected to the input terminal of the third differential amplifier circuit 113.

[0031] The second differential amplifier circuit 112 outputs a second difference signal from its output terminal, which is an amplified version of the voltage difference (i.e., voltage drop) between the input and output sides of the detection resistor 23.

[0032] The output terminal of the first differential amplifier circuit 111 is connected to the positive terminal of the third differential amplifier circuit 113, and the output terminal of the second differential amplifier circuit 112 is connected to the negative terminal. In addition, the output terminal of the third differential amplifier circuit 113 is connected to the input terminal of the second comparator 115.

[0033] The third differential amplifier circuit 113 outputs a third differential signal, which is an amplified version of the voltage difference between the first differential signal and the second differential signal, from its output terminal.

[0034] The first comparator 114 receives a reference voltage (hereinafter referred to as the first reference voltage) at its positive terminal and a first difference signal at its negative terminal. The output terminal of the first comparator 114 is connected to the driver 116. The first comparator 114 outputs a Low signal (no abnormality) if the voltage of the first difference signal is higher than the first reference voltage, and outputs a High signal (abnormality detected) if the voltage of the first difference signal is lower than the first reference voltage. The first reference voltage is set to a value slightly higher than 0V (approximately a few volts).

[0035] The second comparator 115 receives a reference voltage (hereinafter referred to as the second reference voltage) at its positive terminal and a third difference signal at its negative terminal. The output terminals of the second comparator 115 are connected to the driver 116 and the second switch unit 21. The second comparator 115 outputs a High signal (abnormality detected) if the voltage of the third difference signal is higher than the second reference voltage, and outputs a Low signal (no abnormality detected) if the voltage of the third difference signal is lower than the second reference voltage. The second reference voltage is set to a value slightly higher than 0V (approximately a few volts).

[0036] In the circuit configuration shown in Figure 2, the following three patterns will be explained. Note that if both the first DC-DC converter 10 and the second DC-DC converter 20 are malfunctioning, no output current will be supplied to the load, and the malfunction will be detected by the shutdown of the load without the need for the determination circuit 110 to perform malfunction detection. (1) Both the first DC-DC converter 10 and the second DC-DC converter 20 are functioning normally. (2) Only the first DC-DC converter 10 is malfunctioning. (3) Only the second DC-DC converter 20 is malfunctioning.

[0037] (1) Both the first DC-DC converter 10 and the second DC-DC converter 20 are functioning normally. When both the first DC-DC converter 10 and the second DC-DC converter 20 are functioning correctly, a voltage drop occurs across the detection resistors 13 and 23, corresponding to the amount of current flowing through them. In other words, the first difference signal from the first differential amplifier circuit 111 and the second difference signal from the second differential amplifier circuit 112 will both have approximately the same voltage value, corresponding to the voltage drop (because the multi-phase design ensures that the output current is evenly distributed).

[0038] As a result, the first comparator 114 receives a first difference signal with a voltage value above a certain level, which is higher than the first reference voltage (approximately a few volts), causing the first comparator 114 to output a Low signal. In other words, the first comparator 114 determines that there is no abnormality in the first DC-DC converter 10.

[0039] Furthermore, since the third differential amplifier circuit 113 receives the first and second difference signals, which have approximately the same voltage value, the third differential amplifier circuit 113 outputs a third difference signal that is nearly 0V.

[0040] As a result, the second comparator 115 receives a third difference signal that is almost 0V, which is lower than the second reference voltage (a few volts), and the second comparator 115 outputs a Low signal. In other words, the second comparator 115 determines that there is no abnormality in either the first DC-DC converter 10 or the second DC-DC converter 20.

[0041] (2) Only the first DC-DC converter 10 is malfunctioning. Next, if only the first DC-DC converter 10 is malfunctioning, no current flows through the detection resistor 13, resulting in a voltage drop of 0V. In other words, the first differential amplifier circuit 111 outputs a first difference signal that is nearly 0V. On the other hand, a voltage drop occurs across the detection resistor 23, corresponding to the amount of current flowing through it. In other words, the second differential amplifier circuit 112 outputs a second difference signal with a voltage value corresponding to the amount of voltage drop.

[0042] As a result, the first comparator 114 receives a first difference signal with a voltage value of approximately 0V, which is lower than the first reference voltage (approximately a few volts), causing the first comparator 114 to output a High signal. In other words, the first comparator 114 determines that there is an abnormality in the first DC-DC converter 10. Specifically, the determination circuit 110 identifies an abnormality in the first DC-DC converter 10 when the first difference signal, which is the output of the first differential amplifier circuit 111, is 0V.

[0043] Furthermore, the third differential amplifier circuit 113 receives a first difference signal that is nearly 0V and a second difference signal with a voltage value corresponding to the voltage drop. Therefore, the third differential amplifier circuit 113 outputs a third difference signal with a voltage value corresponding to the voltage drop.

[0044] As a result, the second comparator 115 receives a third difference signal of voltage value corresponding to the voltage drop, which becomes higher than the second reference voltage (approximately a few volts), causing the second comparator 115 to output a High signal. In other words, the second comparator 115 determines that there is an abnormality in at least one of the first DC-DC converter 10 and the second DC-DC converter 20.

[0045] Furthermore, since the driver 116 receives a High signal from the first comparator 114, it can identify that an abnormality has occurred in the first DC-DC converter 10. In addition, the second switch unit 21 stops the operation of the second DC-DC converter 20 by receiving a High signal from the second comparator 115. In other words, the second DC-DC converter 20 can avoid performing the unreasonable operation required to supply the output current of the first DC-DC converter 10 due to the abnormality in the first DC-DC converter 10.

[0046] (3) Only the second DC-DC converter 20 is malfunctioning. Next, if only the second DC-DC converter 20 is malfunctioning, no current flows through the detection resistor 23, resulting in a voltage drop of 0V. In other words, the second differential amplifier circuit 112 outputs a second difference signal that is nearly 0V. On the other hand, a voltage drop occurs across the detection resistor 13, corresponding to the amount of current flowing through it. In other words, the first differential amplifier circuit 111 outputs a first difference signal with a voltage value corresponding to the amount of voltage drop.

[0047] As a result, the first comparator 114 receives a first difference signal of voltage value corresponding to the voltage drop, which becomes higher than the first reference voltage (approximately a few volts), and the first comparator 114 outputs a Low signal. In other words, the first comparator 114 determines that there is no abnormality in the first DC-DC converter 10.

[0048] Furthermore, the third differential amplifier circuit 113 receives a first difference signal with a voltage value corresponding to the voltage drop and a second difference signal that is nearly 0V. Therefore, the third differential amplifier circuit 113 outputs a third difference signal with a voltage value corresponding to the voltage drop.

[0049] As a result, the second comparator 115 receives a third difference signal with a voltage value corresponding to the voltage drop, which becomes higher than the second reference voltage (approximately a few volts), causing the second comparator 115 to output a High signal. In other words, the second comparator 115 determines that there is an abnormality in at least one of the first DC-DC converter 10 and the second DC-DC converter 20. Specifically, the determination circuit 110 identifies an abnormality in the second DC-DC converter 20 when the second difference signal, which is the output of the second differential amplifier circuit 112, is 0V.

[0050] Furthermore, since the driver 116 receives a Low signal from the first comparator 114, it can identify that an abnormality has occurred in the second DC-DC converter 20 by receiving a High signal from the second comparator 115. The driver 116 then stops the switching control. The second switch unit 21 also stops the operation of the second DC-DC converter 20 by receiving a High signal from the second comparator 115. In other words, the first DC-DC converter 10 can avoid performing unreasonable operations to supply the output current of the second DC-DC converter 20 due to the abnormality of the second DC-DC converter 20.

[0051] As described above, the power supply circuit 1 according to the embodiment comprises a plurality of DC-DC converters, a plurality of detection circuits (detection resistors 13, 23), and a determination circuit 110. The plurality of DC-DC converters are connected in parallel to the load. The plurality of detection circuits are provided for each of the plurality of DC-DC converters and detect the output current of each of the plurality of DC-DC converters. The determination circuit 110 is provided for any of the plurality of DC-DC converters and compares the output currents detected by the plurality of detection circuits and determines an abnormality in the plurality of DC-DC converters based on the comparison result.

[0052] According to this disclosure, a determination circuit 110 is provided in one of the multiple DC-DC converters, and the determination circuit 110 detects abnormalities in the multiple DC-DC converters. In other words, in this disclosure, by equipping the abnormality detection function in one of the DC-DC converters, a dedicated abnormality detection device is not required, and abnormalities in multiple DC-DC converters can be detected without increasing the circuit size.

[0053] Further effects and modifications can be readily derived by those skilled in the art. Therefore, broader aspects of the present invention are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents. [Explanation of Symbols]

[0054] 1 Power circuit 10. First DC-DC Converter 11. First switch section 12, 22 coils 13, 23 detection resistors 14, 24 Capacitors 20. Second DC-DC converter 21 Second Switch Section 110 Judgment circuit 111 First Differential Amplifier Circuit 112 Second Differential Amplifier Circuit 113 Third Differential Amplifier Circuit 114 First Comparator 115 Second Comparator 116 Drivers 117 First Switching Elements 118 Second switching element

Claims

1. Multiple DC-DC converters connected in parallel to the load, Each of the aforementioned plurality of DC-DC converters is provided with a plurality of detection circuits that detect the output current of each of the plurality of DC-DC converters, A determination circuit provided in one of the plurality of DC-DC converters compares the output currents detected by the plurality of detection circuits and determines an abnormality in the plurality of DC-DC converters based on the comparison result, A power supply circuit equipped with the following features.

2. The aforementioned determination circuit is It has a comparison circuit for comparing the output currents, Based on the comparison results of the comparison circuit, the DC-DC converter in which an abnormality is occurring is identified among the multiple DC-DC converters, and the control of the identified DC-DC converter is stopped. The power supply circuit according to claim 1.

3. The aforementioned comparison circuit is It is a differential amplifier circuit, The aforementioned determination circuit is By comparing the output of the differential amplifier circuit with a threshold value, the DC-DC converter experiencing an abnormality can be identified. The power supply circuit according to claim 2.

4. The detection circuit is A circuit for detecting the voltage drop across a resistor provided in the DC-DC converter as the output current, The differential amplifier circuit is The difference in the voltage drop amounts of each of the aforementioned multiple DC-DC converters is output. The aforementioned determination circuit is By comparing the difference in the voltage drop amount with a threshold, the DC-DC converter experiencing the malfunction can be identified. The power supply circuit according to claim 3.

5. The aforementioned determination circuit is If the difference in the voltage drop amount, which is the output of the differential amplifier circuit, is zero, it is identified as the DC-DC converter where the malfunction is occurring. The power supply circuit according to claim 4.

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