Rectifier circuit and power supply device
The rectifier circuit, featuring a high and low withstand voltage transistor along with a control transistor, addresses the issue of reverse recovery current losses, resulting in improved efficiency.
Patent Information
- Application Number
- JP2023185134
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-10-30
- Publication Date
- 2025-05-14
- Estimated Expiration
- 2043-10-30
AI Technical Summary
Existing rectifier circuits still experience significant losses due to reverse recovery current, despite efforts to reduce it.
A rectifier circuit comprising a high withstand voltage transistor, a low withstand voltage transistor, and a control transistor, with specific connections and configurations to minimize reverse recovery current.
The proposed rectifier circuit effectively reduces losses by minimizing reverse recovery current, achieving better performance than previous designs.
Smart Images
Figure 2025074382000001_ABST
Abstract
Description
[Technical field]
[0001] The following disclosure relates to a rectifier circuit and a power supply device. [Background technology]
[0002] In a rectifier circuit, switching loss occurs due to a reverse recovery current. For this reason, studies are being conducted to reduce the reverse recovery current. One example is disclosed in Patent Document 1. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] JP 2016-220468 A Summary of the Invention [Problem to be solved by the invention]
[0004] However, even with such a rectifier circuit, there is still room for improvement.
[0005] This specification discloses a rectifier circuit and a power supply device that can reduce losses compared to conventional devices. [Means for solving the problem]
[0006] In order to solve the above problems, a rectifier circuit according to one aspect of the present disclosure is a rectifier circuit including a high-voltage transistor, a low-voltage transistor, and a control transistor. The reference terminal of the high voltage transistor is connected to the high voltage terminal of the low voltage transistor. The control terminal of the high voltage transistor is connected to the reference terminal of the low voltage transistor via a capacitor. The control transistor has a high voltage terminal connected to the control terminal of the high voltage transistor, a reference terminal connected to the reference terminal of the low voltage transistor, and a control terminal connected to the high voltage terminal of the low voltage transistor.
[0007] In order to solve the above problems, a power supply device according to one aspect of the present disclosure is a power supply device including the above rectifier circuit. Effect of the Invention
[0008] According to the present disclosure, it is possible to reduce losses more than ever before. [Brief description of the drawings]
[0009] [Figure 1] FIG. 2 is a diagram showing the configuration of a rectifier circuit according to the present disclosure. [Diagram 2] FIG. 1 is a diagram showing a power supply circuit to which a rectifier circuit according to the present disclosure is applied. [Diagram 3] 6 is a diagram showing the effect of reducing reverse recovery current of the rectifier circuit of the present disclosure. [Figure 4] FIG. 1 is a diagram showing a power supply device including a rectifier circuit according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] [Embodiment 1] This specification discloses a rectifier circuit capable of reducing reverse recovery current. As an example of the symbols in the drawings, the rectifier circuit RC1 is also written simply as RC1. The abbreviations used are as follows: MOS stands for metal-oxide-semiconductor field-effect transistor.
[0011] (Main components of a rectifier circuit) FIG. 1 shows the configuration of a rectifier circuit RC1 that reduces the reverse recovery current. RC1 has a high-voltage transistor HVT1, a low-voltage transistor LVT1, and a control transistor CNT1. HVT1, LVT1, and CNT1 have a reference terminal, a control terminal, and a high-voltage terminal. The control terminal is a terminal that applies a voltage or current that controls the ON / OFF of the transistor. The reference terminal is a terminal that serves as the reference for the voltage and current applied to the control terminal. The high-voltage terminal is a terminal that can receive a high voltage when the transistor is turned OFF by the control terminal. For example, the drain terminal of a MOS transistor. RC1 includes a capacitor CAP1 and a resistor RES1. A voltage is supplied to CAP1 by connecting it to an auxiliary power supply (not shown).
[0012] The reference terminal of HVT1 is connected to the high voltage terminal of LVT1. The control terminal of HVT1 is connected to the reference terminal of LVT1 via a resistor RES1 and a capacitor CAP1 in that order. The reference terminal of CNT1 is connected to the reference terminal of LVT1, the control terminal is connected to the high voltage terminal of LVT1, and the high voltage terminal is connected to the control terminal of HVT1.
[0013] (Detailed configuration of the rectifier circuit) HVT1 is an N-channel MOS with a high-voltage terminal withstand voltage of 600V. LVT1 is an N-channel MOS with a high-voltage terminal withstand voltage of 30V. HVT1 is set to have a withstand voltage more than 10 times higher than LVT1. CNT1 is an N-channel MOS with a high-voltage terminal withstand voltage of 20V. The threshold voltage for turning on the transistors is 5V for HVT1, 3V for LVT1, and 1V for CNT1. The ON resistance of the transistors is 50 mΩ for HVT1, 3 mΩ for LVT1, and 1 Ω for CNT1. The resistance of RES1 is 62Ω and the voltage of CAP1 is 15V.
[0014] (Rectifier circuit operation and reverse recovery current) By applying a forward voltage to RC1, a rectified current can be made to flow from the reference terminal of LVT1 to the high voltage terminal of HVT1. In addition, by applying a reverse voltage to RC1, the rectified current can be stopped. At the start of the application of the reverse voltage, reverse recovery occurs in RC1, which generates a reverse recovery current in the opposite direction to the rectified current. After this reverse recovery is complete, all current in RC1 stops.
[0015] HVT1 and LVT1 are configured so that their conduction periods overlap. When rectified current is flowing, the parasitic diode of LVT1 conducts and the HVT1 channel automatically turns on, allowing current to flow to the channel side. The conduction on the channel side of HVT1 suppresses the conduction of the parasitic diode, and the reverse recovery current of the parasitic diode can be suppressed. When rectified current is flowing, synchronous rectification can also be implemented by turning LVT1 on with an external signal.
[0016] HVT1 and LVT1 are configured to overlap with each other in terms of non-conduction periods. The reverse voltage turns off the parasitic diode of LVT1, and the voltage of the high voltage terminal relative to the reference voltage terminal of LVT1 rises. As a result, the voltage of the control terminal relative to the reference voltage terminal of HVT1 falls below the threshold voltage, and the channel of HVT1 turns off. Thus, both HVT1 and LVT1 are non-conductive.
[0017] (Operation as a switch circuit) As described above, RC1 can be used as a rectifier circuit, but it can also operate as a switch circuit. RC1 can also perform switching operation by applying a voltage to the control terminal of LVT1 to turn it ON when a voltage is applied to the high voltage terminal of HVT1 with reference to the reference terminal of LVT1. This is because RC1 is configured to turn HVT1 ON in conjunction with LVT1 being turned ON.
[0018] (Transistor application example) In addition to SJ-MOS, the HVT1 can also be used with high-voltage transistors such as SiC-MOS, GaN-HEMT, and JFET. The LVT1 and CNT1 can be applied to low-voltage transistors such as GaN-HEMTs and bipolar transistors in addition to Si-MOS.
[0019] (Prevents capacitor over-discharge and turns off quickly) In this embodiment, RES1 is disposed between CAP1 and the high voltage terminal of CNT1. In addition, the high voltage terminal of CNT1 is connected to the control terminal of HVT1. This is for the purpose of achieving both prevention of excessive discharge of CAP1 when CNT1 is turned ON and high speed OFF of the control terminal of HVT1. If excessive discharge of CAP1 is not a problem, the arrangement of RES1 can be omitted.
[0020] (Overdrive voltage of high-voltage transistor and threshold voltage of control transistor) The threshold voltage of CNT1 is configured to be lower than the voltage of CAP1 minus the threshold voltage of HVT1. Specifically, the voltage (overdrive voltage) obtained by subtracting the HVT1 threshold value of 5V from the CAP1 voltage of 15V is configured to be 10V. While the voltage between the reference terminal and high voltage terminal of LVT1 rises to 10V, which is the overdrive voltage in this example, the voltage between the reference terminal and control terminal of HVT1 exceeds the threshold value, so HVT1 is in the ON state. During the reverse recovery period, HVT1 flows a reverse current without being turned OFF, so it is necessary to turn it OFF early. If the threshold voltage of CNT1 is smaller than 10V, HVT1 can be turned OFF first by CNT1. Since the threshold voltage of CNT1 is set to 1V, which is lower than 10V, HVT1 can be turned OFF early.
[0021] The threshold voltage of CNT1 is preferably equal to or less than half the value obtained by subtracting the threshold voltage of HVT1 from the voltage of CAP1. Considering malfunctions due to noise, the threshold voltage of CNT1 is preferably equal to or greater than 0.5V.
[0022] (Power supply circuit using the rectifier circuit of the present disclosure) The boost power supply circuit PS1 using RC1 is shown in Figure 2. PS1 includes RC1, a rectifier circuit RC2, a gate drive circuit GD1, a boost coil CO1, and a bus capacitor BC1. The rectifier circuit RC2 has the same configuration as RC1. RC1 functions as a rectifier circuit that passes rectified current. RC2 functions as a switch circuit that excites CO1. The PS1 outputs a voltage of 400V from an input voltage of 200V (not shown).
[0023] The high voltage terminal of HVT1 of RC1 is connected to the positive pole of BC1, 400 V. The reference terminal of LVT1 of RC1 is connected to the switch node, which is one end of CO1. The high voltage terminal of HVT1 of RC2 is connected to one end of CO1. The reference terminal of LVT1 of RC2 is connected to the negative pole 0V of BC1.
[0024] Since RC1 and RC2 are circuits with the same configuration, it is possible to switch between the rectification and switching functions. Therefore, PS1 can also operate as a step-down circuit that inputs 400V power and outputs 200V. PS1 can also be used as an inverter circuit that handles AC.
[0025] (Reducing the reverse recovery current of the rectifier circuit) In this embodiment, the effect of reducing the reverse recovery current when the PS1 is operated as a boost circuit is disclosed in Fig. 3. In Fig. 3, the reverse recovery current is represented as a negative current. The dotted line CONVI shows the reverse recovery current of a circuit in which CNT1 is not included in RC1. The solid line RC1I shows the reverse recovery current of RC1. The maximum negative current is 17.8 A for CONVI and 17.4 A for RC1I. It can be seen that RC1I is 0.4 A less.
[0026] [Embodiment 2] An example of a power supply unit PU1 using RC1 is shown in Figure 4. PU1 includes a PS1 equipped with RC1. RC1 can suppress reverse recovery current, allowing the configuration of PU1 with reduced losses.
[0027] It should be noted that the values given above are merely examples. In order to adjust the circuit operation, resistors can be inserted in the wiring, capacitors can be added between the wiring, and so on.
[0028] [Additional Notes] The presently contemplated embodiments of the invention disclosed above may be modified in various ways as necessary, and it is intended that the appended claims encompass all such modifications as fall within the true spirit and scope of the invention. [Explanation of symbols]
[0029] RC1 rectifier circuit HVT1 High-Voltage Transistor LVT1 Low voltage transistor CNT1 control transistor RES1 Resistor CAP1 Capacitor BC1 Bus Capacitor CO1 coil RC2 rectifier circuit GD1 Gate drive circuit PS1 power supply circuit PU1 power supply
Claims
1. A rectifier circuit including a high-voltage transistor, a low-voltage transistor, and a control transistor, a reference terminal of the high voltage transistor is connected to a high voltage terminal of the low voltage transistor; a control terminal of the high voltage transistor is connected to a reference terminal of the low voltage transistor via a capacitor; The control transistor is a high voltage terminal connected to a control terminal of the high voltage transistor; a reference terminal connected to the reference terminal of the low voltage transistor; a rectifier circuit having a control terminal connected to the high voltage terminal of the low voltage transistor.
2. 2. The rectifier circuit according to claim 1, further comprising a resistor connected between said capacitor and the high voltage terminal of said control transistor.
3. 2. The rectifier circuit according to claim 1, wherein the threshold voltage of said control transistor is lower than a value obtained by subtracting the threshold voltage of said high voltage transistor from the voltage of said capacitor.
4. A power supply device comprising the rectifier circuit according to claim 1.
Citation Information
Patent Citations
DC / ac inverter
JP2016220468A