CN111799998B

CN111799998B - Converter suitable for high-voltage electronic equipment

Info

Publication number: CN111799998B
Application number: CN202010278078.5A
Authority: CN
Inventors: 刘剑
Original assignee: Siemens Electric Vehicle Powertrain System Shanghai Co ltd
Current assignee: Valeo Automotive ePowertrain Systems Shanghai Co Ltd; Valeo eAutomotive Changshu Co Ltd
Priority date: 2020-04-10
Filing date: 2020-04-10
Publication date: 2021-09-28
Anticipated expiration: 2040-04-10
Also published as: CN111799998A

Abstract

The invention relates to a converter (200) which comprises a starting capacitor (C1), a control unit (66), a transformer and a starting control circuit (300), wherein the starting control circuit (300) is used for regulating and controlling a current for starting the control unit (66); the start-up control circuit (300) includes a current source module (310,310b,310C) electrically connected to the start-up capacitor (C1), the control unit (66) and a primary winding (Lpri) of the transformer; the current source module (310,310b,310c) comprises a voltage regulator (V1), a first regulation element (312), and a source current sampling resistor (Rcs) for cooperating with the first regulation element (312) to adjust the conductivity of the voltage regulator (V1); the current source module (310,310b,310C) generates a source current (Isc) to charge the start-up capacitor (C1) according to the voltage value of the first regulation element (312) and the resistance value of the source current sampling resistor (Rcs).

Description

Converter suitable for high-voltage electronic equipment

Technical Field

The present invention relates to inverters for electronic devices, and more particularly to starting inverters for high voltage electronic devices.

Background

In a circuit design of a conventional converter (converter), such as a Flyback converter or a forward converter, the converter includes a controller and a start-up circuit, the start-up circuit regulates an initial current of the controller for starting the converter, and in the prior art, the start-up circuit usually includes a resistor with a high resistance value, as shown in fig. 1.

Fig. 1 is a schematic diagram of a portion of the circuitry within a flyback converter 10a of the prior art. The flyback converter 10a is disposed in an electronic device, which may be a high-voltage electronic device, such as a vehicle charger. The flyback converter 10a includes a converter switch V0, a control unit 66, a start resistor Rst, a start capacitor C1, at least one filter capacitor (e.g., C2 and Cin shown in fig. 1), an isolation diode D1, at least one rectifier diode (e.g., D2 shown in fig. 1), a transformer (transformer), and a first sampling resistor Rs. The transformer includes a primary winding Lpri, a secondary winding Lsec and an auxiliary winding Laux.

Converter switch V0 is the overall switch of the entire flyback converter 10a, which is a power electronic switch. The converter switch V0 may be a Field-Effect Transistor (FET), such as a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). The first sampling resistor Rs is electrically connected to the inverter switch V0 for sampling the current of the inverter switch V0. The control unit 66 may be a Pulse Width Modulation (PWM) controller. An isolation diode D1 has one end electrically connected to the auxiliary winding Laux and the other end electrically connected to the starting capacitor C1 and the control unit 66 for isolating the power supply of the control chip of the control unit 66 from the power supply of other circuits.

In the example of fig. 1, the at least one filter capacitor includes an output capacitor C2 and an input capacitor Cin. Output capacitor C2 is electrically connected to secondary winding Lsec and input capacitor Cin is electrically connected to primary winding Lpri. The at least one rectifying diode includes an output rectifying diode D2. An output rectifying diode D2 is electrically connected to the secondary winding Lsec at one end and to the output capacitor C2 at the other end for rectifying the pulses of the secondary winding Lsec into a direct current.

An input power is inputted from an input terminal 9a of the flyback converter 10a, and the voltage value of the input power is Vin. The input power may be a high voltage power. A first node J1 is provided between the input terminal 9a and the primary winding Lpri, a second node J2 is provided between one end of the start capacitor C1 and the control unit 66, and two ends of the start resistor Rst are electrically connected to the first node J1 and the second node J2, respectively. Three terminals (terminals) of the converter switch V0 are electrically connected to the primary winding Lpri, the control unit 66, and one end of the resistor Rst via a third node J3. The other end of the resistor Rst is grounded. In addition, the third node J3 is also electrically connected to the control unit 66. At the output end 9b of the flyback converter 10a, an output with a voltage value Vout is obtained at an output end 9b of the flyback converter 10 a.

During the start-up of the flyback converter 10a, the input power continuously charges the start-up capacitor C1 for a charging time TC, which occupies most of the time required for the start-up of the flyback converter 10a, through the start-up resistor Rst; when the voltage Vcc of start-up capacitor C1 is equal to or greater than a start-up voltage thresholdAt value Vsth, flyback converter 10a is activated and auxiliary winding Laux begins to supply power to control unit 66. The length of the charging required time TC can be calculated by the following equation:

where Rst represents the resistance value of the start resistor Rst, and C1 represents the capacitance value of the start capacitor C1. Therefore, the larger the resistance value of the start resistor Rst, the longer the charging time TC, which results in the longer the start time of the flyback converter 10 a.

When the flyback converter 10a is started and enters a steady operation state, the voltage Vcc of the start capacitor C1 is adjusted to a specific value, for example, 15 volts (Volt), and the voltage difference across the start resistor Rst is (Vin-Vcc), and the value of the voltage across the start resistor Rst is used to calculate the power loss PL caused by using the start resistor Rst, and the detailed algorithm is shown in the following formula:

as can be seen, the power loss PL is inversely proportional to the resistance of the start resistor Rst, and also inversely proportional to the charging time TC and the time required for starting the flyback converter 10 a. In an ultra-wide input range application, for example, the voltage range of the auxiliary high voltage power supply of an inverter for a vehicle can be as low as 40 volts and as high as 550 volts, if the power loss PL is required to be limited within an acceptable range, a start resistor Rst with a very high resistance value is usually adopted, and a current input at a low voltage (which causes a low voltage input condition to provide a very small start current) is usually adopted, however, the flyback converter 10a needs to start for a long time, which is contradictory to the fast start required by the vehicle equipment, so that the requirements of the user of the vehicle or the functional safety requirements of the vehicle itself cannot be met.

Another way is to replace the high resistance start resistor Rst of the flyback converter 10a shown in fig. 1 with a current source circuit 31, as shown in fig. 2. Fig. 2 is a schematic diagram of a portion of circuitry within another prior art flyback converter 10 b. The current source circuit 31 is electrically connected to the first node J1 and the second node J2, respectively. The remaining components of flyback converter 10a shown in fig. 1, except for start resistor Rst, are similar or identical in function to the components of flyback converter 10b shown in fig. 2 that are the same name and number.

The current source circuit 31 includes a source resistor Rc and a voltage regulator Va. One end of the source resistor Rc is electrically connected to the voltage regulator Va, and the other end is electrically connected to the second node J2. The voltage regulator Va has one end electrically connected to the first node J1 and the other two ends electrically connected to the source resistor Rc. The voltage regulator Va may be a MOSFET transistor, and preferably an N-Channel Depletion MOSFET transistor is used as the voltage regulator Va. Further, the source resistor Rc is different from the starting resistor Rst shown in fig. 1 in that the source resistor Rc functions as a current sample and constitutes a constant current source with the N-channel depletion type MOSFET transistor Va.

When the input power flows through the source resistor Rc, the voltage difference across the source resistor Rc is used as the negative gate voltage drive of the voltage regulator Va. If the gate driving voltage of the voltage regulator Va is a negative value, a negative feedback closed loop can be formed between the voltage regulator Va and the source resistor Rc. In the steady state, the gate threshold voltage of the voltage regulator Va has a value Vgth, and an output current Ic outputted from the current source circuit 31 to the start capacitor C1 can be a constant value, which can be calculated by the following formula:

where Rc is the resistance value of the source resistor Rc.

However, although the use of the source resistor Rc and the voltage regulator Va can avoid the problem of the long time required for starting the converter due to the use of the high-resistance start resistor Rst and the low-voltage current input, the following three disadvantages are caused. First, the high voltage N-channel depletion MOSFET used as the voltage regulator Va is a rare and expensive device, and it does not always maintain stable operation for a long time. Moreover, if the input power is a high-voltage current, high power loss will still be caused, resulting in low working efficiency of the converter, and a corresponding heat dissipation design needs to be added to the converter. In addition, when different types of MOSFET transistors are used as the voltage regulator Va, the gate threshold voltage Vgth varies and depends on the temperature, which may cause the output current Ic to no longer have a constant value as mentioned above, i.e., the output current Ic has a potential stability problem.

Disclosure of Invention

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an inverter suitable for high-voltage electronic equipment, which has a low-cost and highly efficient start control circuit, can start the inverter in a short time, and can effectively reduce power loss.

In order to achieve the purpose, the invention adopts the following technical scheme:

a converter comprises a starting capacitor, a control unit, a transformer and a starting control circuit, wherein the starting control circuit is used for regulating and controlling a current for starting the control unit; the starting control circuit comprises a current source module which is electrically connected with the starting capacitor, the control unit and a primary winding of the transformer; the current source module comprises a voltage regulator, a first regulation and control element and a source current sampling resistor, wherein the source current sampling resistor is used for cooperating with the first regulation and control element to regulate the conductivity of the voltage regulator; the current source module generates a source current to charge the starting capacitor according to the voltage value of the first regulation and control element and the resistance value of the source current sampling resistor.

Furthermore, the start-up control circuit further comprises a start-up state judgment module for controlling the voltage regulator to turn off the current source module in operation when the converter enters a normal operation stage after being started up.

Further, the current source module further comprises a gate bias resistor for providing a gate bias voltage to the voltage regulator; and a plurality of bias resistors for setting an operating point (operating point) of the first regulating element.

Further, the current source module forms a closed-loop control circuit to gradually adjust the source current.

Further, the first regulation and control element is a triode.

Further, the value of the source current Isc output by the current source module is calculated by the following formula:

wherein Rcs is a resistance value of the source current sampling resistor, and Vbe is a value of a silicon PN junction (silicon PN junction) forward voltage drop of the first regulation element.

Further, the plurality of bias resistors includes a base current limiting resistor and a base pull-down resistor.

Further, the current source module further comprises a second regulating element electrically connected between the voltage regulator and the source current sampling resistor; a temperature coefficient of the second control element is directly proportional to a forward voltage drop of the silicon PN junction of the first control element.

Further, the second control element is a Schottky Barrier Diode (Schottky Barrier Diode).

wherein Rcs is a resistance value of the source current sampling resistor, Vbe is a value of a forward voltage drop of a silicon PN junction of the first regulation element, and VSBD is a value of a forward voltage drop of the second regulation element.

Further, the first control element is a precision voltage shunt integrated circuit (precision voltage shunt integrated circuit), and the value of the source current Isc output by the current source module is calculated by the following formula:

wherein Rcs is the resistance of the source current sampling resistor Rcs, and Vreg is an internal reference voltage value of the precision voltage parallel integrated circuit.

Further, the plurality of bias resistors includes a first voltage dividing resistor and a second voltage dividing resistor.

Furthermore, the starting state judgment module is used for judging whether to close the current source module in operation according to the received auxiliary side rectification voltage; an auxiliary winding of the transformer rectifies the voltage of the starting capacitor to generate the auxiliary side rectified voltage.

Further, the converter further comprises: an auxiliary side output capacitor for filtering the voltage outputted by the auxiliary winding; and an auxiliary side rectifying diode electrically connected to the auxiliary side output capacitor, the auxiliary winding and the starting state judging module, wherein the auxiliary winding rectifies the voltage of the starting capacitor through the auxiliary side rectifying diode to generate the auxiliary side rectified voltage.

Further, the voltage regulator is an N-Channel Enhancement type metal oxide semiconductor field effect Transistor (N-Channel Enhancement MOSFET) or an Insulated Gate Bipolar Transistor (Insulated Gate Bipolar Transistor).

Further, an input power received by the converter is a high voltage power.

Further, the converter is one of the following converters: a Flyback converter, a forward converter, a half-bridge converter or a full-bridge converter.

Drawings

FIG. 1 is a schematic diagram of a portion of the circuitry within a flyback converter of the prior art;

FIG. 2 is a schematic diagram of a portion of circuitry within another prior art flyback converter;

FIG. 3 is a schematic diagram of one embodiment of a converter of the present invention;

fig. 4 and 5 are simplified schematic diagrams of current source modules of converters according to another two embodiments of the present invention.

Detailed Description

The essential features and advantages of the invention will be explained in more detail below with reference to the drawings and exemplary embodiments, to which the invention is not restricted.

The converter of the invention is arranged in an electronic device and can be started by high-voltage power supply, and the electronic device can be a high-voltage electronic device, such as a charger for a vehicle. In the present embodiment, the converter 200 is a Flyback converter (Flyback converter), such as the Flyback converter 200 shown in fig. 3. However, in other embodiments, the converter 200 may be other types of converters, such as a forward converter (forward converter), a half-bridge converter, or a full-bridge converter. An input power is inputted from an input terminal 9a of the converter 200, and the voltage value of the input power is Vin, which is between 20 volts and 700 volts, that is, the input power can be a high voltage power if necessary.

The converter 200 includes a converter switch V0, a control unit 66, a start control circuit 300, a start capacitor C1, at least one filter capacitor (e.g., C2, Cin, and C11 shown in fig. 3), an isolation diode D1, at least one rectifier diode (e.g., D2, D11 shown in fig. 3), a transformer, and a first sampling resistor Rs. The transformer includes a primary winding Lpri, a secondary winding Lsec and an auxiliary winding Laux. The control unit 66 may be a Pulse Width Modulation (PWM) controller. There is a first node J1 between the input terminal 9a and the primary winding Lpri, and a second node J2 between one terminal of the start capacitor C1 and the control unit 66.

In the embodiment shown in fig. 3, the at least one filter capacitor includes an output capacitor C2, an input capacitor Cin, and an auxiliary side output capacitor C11, and the capacitors C2, Cin, and C11 all have a filtering function; the at least one rectifying diode includes an output rectifying diode D2 and an auxiliary side rectifying diode D11. The auxiliary side output capacitor C11 and the auxiliary side rectifier diode D11 will be described later.

The converter switch V0, the control unit 66, the start capacitor C1, the output capacitor C2, the input capacitor Cin, the isolation diode D1, the output rectifying diode D2, the transformer and the first sampling resistor Rs, and the first, second and third nodes J1, J2 and J3 of the present embodiment are similar or identical in function to the same-name and same-number components of the flyback converter 10a of the related art shown in fig. 1, and are described in detail in the related paragraphs above, so they are not described in detail again.

The start-up control circuit 300 is used to start up the converter 200 in a short time. The start-up control circuit 300 includes a current source module 310, the current source module 310 is electrically connected to the start-up capacitor C1, the control unit 66 and the primary winding Lpri, that is, as shown in fig. 3, the current source module 310 is electrically connected to the first node J1 and the second node J2. The current source module 310 includes a gate bias resistor Rg, a voltage regulator V1, a source current sampling resistor Rcs, and at least one regulation element. The current source module 310 is used for generating a source current Isc to charge the start capacitor C1 according to the voltage value of the at least one regulation element and the resistance value of the source current sampling resistor Rcs.

In the embodiment shown in FIG. 3, the at least one regulatory element comprises a first regulatory element 312. Preferably, the first control element 312 is a Triode (Triode). Additionally, in one embodiment, voltage regulator V1 is a Field Effect Transistor (FET); preferably, the voltage regulator V1 is an N-Channel Enhancement MOSFET (N-Channel Enhancement MOSFET) transistor; in yet another embodiment, voltage regulator V1 is an Insulated Gate Bipolar Transistor (IGBT) Transistor.

Preferably, the current source module 310 further includes a plurality of bias resistors Rb1 and Rb2 for cooperating with each other to set an operating point (operating point) of the first regulating element 312. In the embodiment, the bias resistors Rb1 and Rb2 include a first bias resistor Rb1 and a second bias resistor Rb2, but the invention is not limited to the number of bias resistors. Preferably, the gate bias resistor Rg, the bias resistors Rb1 and Rb2, and the source current sampling resistor Rcs are all not power resistors, so that the power loss of the current source module 310 is much lower during operation compared to the flyback converter 10a of the prior art using the start resistor Rst with a high resistance value.

In one embodiment, three terminals (terminals) of the voltage regulator V1 are electrically connected to the first node J1, a fourth node J4 and a sixth node J6, respectively. Two ends of the gate bias resistor Rg are electrically connected to the first node J1 and the fourth node J4, respectively. The first control element 312 has three terminals electrically connected to the second node J2, the fourth node J4 and a fifth node J5, respectively. The bias resistors Rb1, Rb2 and the source current sampling resistor Rcs are further disposed between the voltage regulator V1 and the first regulating element 312. In the embodiment shown in fig. 3, the bias resistors Rb1, Rb2 (first and second bias resistors Rb1, Rb2, respectively) include a plurality of base resistors. Preferably, the first and second bias resistors Rb1, Rb2 are a base current limiting resistor Rb1 and a base pull-down resistor Rb2, respectively. Two ends of the first bias resistor Rb1 are electrically connected to the fifth node J5 and the sixth node J6, respectively. Two ends of the second bias resistor Rb2 are electrically connected to the fifth node J5 and the second node J2, respectively. The source current sampling resistor Rcs is electrically connected to the second node J2 and the sixth node J6 at two ends.

During start-up of converter 200, initially, gate bias resistor Rg provides the gate bias voltage for voltage regulator V1, and then voltage regulator V1 slowly begins to conduct. When the input power flows through the source current sampling resistor Rcs and when the voltage difference VRcs across the source current sampling resistor Rcs exceeds the value Vbe of the silicon PN junction (forward voltage drop) of the first regulation element 312, the voltage difference VRcs across the source current sampling resistor Rcs provides a base current to the first regulation element 312, and the first regulation element 312 is turned on, which causes the gate voltage of the voltage regulator V1 to decrease, thereby decreasing the conductivity of the voltage regulator V1, and decreasing a source current Isc output by the current source module 310, such that the current source module 310 forms a closed-loop control circuit and gradually and appropriately adjusts the value of the source current Isc.

The current source module 310 is used asA separate current source used by the converter 200 during start-up continuously charges the start-up capacitor C1, and in a steady state, the source current Isc output from the current source module 310 to the start-up capacitor C1 may be a constant value, which is calculated by the following formula:

wherein Rcs is the resistance value of the source current sampling resistor Rcs. The present invention allows the time TS required for starting the converter 200 to be set by setting a suitable current value of the source current Isc, and the present invention allows the time TS required for starting to be very small, that is, the present invention can meet the requirement of fast starting required by the vehicle equipment, and further meet the requirement of safety for vehicle use and the requirement of users, which cannot be achieved by the two prior

art flyback converters

10a and 10b (each using the start resistor Rst and the current source circuit 31 with high resistance values).

The value Vbe of the forward voltage drop of the silicon PN junction of the first regulation element 312 of the current source module 310 shown in fig. 3 depends on the temperature to a large extent, and an excessively high temperature may affect the value of the source current Isc output by the current source module 310. Therefore, in order to prevent the generated source current Isc from being affected by the temperature, the transistor used as the first regulation element 312 in the current source module 310 may be replaced by a precision voltage shunt integrated circuit (precision voltage shunt integrated circuit), as shown in the current source module 310b of fig. 4. Compared with a triode, the reference voltage of the IC circuit is more precise, and the provided control precision is higher. In addition, in the present embodiment, the bias resistors Rb1, Rb2 for cooperating with each other to set the operating point of the first regulating element 312 (in this case, the precision voltage parallel integrated circuit) are a first voltage dividing resistor Rb1 and a second voltage dividing resistor Rb2, respectively.

The current source module 310b is a preferred embodiment of the current source module 310 of fig. 3, and the connection relationship and configuration between the current source module 310 and other components and assemblies in the converter 200 are similar or identical to the connection relationship and configuration between the current source module 310 and other components and assemblies in the converter 200.

The first control element 312 is a precision voltage parallel integrated circuit, which can precisely eliminate the influence of temperature on the value of the source current Isc output by the current source module 310 b. Preferably, a low-voltage adjustable precision shunt regulator with a model number of TLV431 and a precision of 1.5% can be selected as the voltage regulation element 312 of the current source module 310 b. The precision voltage parallel integrated circuit 312 is electrically connected to the gate bias resistor Rg via a fourth node J4, the bias resistors Rb1 and Rb2 via a fifth node J5, and the start-up capacitor C1 via a second node J2. In addition, the end of the gate bias resistor Rg that is originally electrically connected to the first node J1 (as shown in fig. 3) is not electrically connected to the first node J1, but is instead electrically connected to a low voltage power source VL (as shown in fig. 4); preferably, the voltage supplied by the low voltage power supply VL has a value of 15 volts. Thus, the gate bias resistor Rg is used to power the precision voltage shunt ic 312 in addition to providing the gate voltage for the voltage regulator V1. The remaining components of the current source module 310b, which have the same functions as or are the same as the components with the same names and numbers included in the current source module 310 of fig. 3, have been described in detail in the related paragraphs, and therefore are not described in detail.

The value of the source current Isc output by the current source module 310b may be calculated by the following equation:

where Rcs is the resistance of the source current sampling resistor Rcs and Vreg is an internal reference voltage value of the precision voltage parallel integrated circuit 312. Thus, the source current Isc output by the current source module 310b is not affected by temperature.

In another embodiment, if the first regulation element 312 of the current source module 310 is a transistor, the at least one regulation element may further include a second regulation element 314, as shown in the current source module 310c of fig. 5, for preventing the source current Isc generated by the current source module 310c from being affected by temperature. In addition, in the present embodiment, the bias resistors Rb1, Rb2 for cooperating with each other to set the operating point of the first regulating element 312 are preferably a base current limiting resistor Rb1 and a base pull-down resistor Rb2, respectively. The current source module 310c is a preferred embodiment of the current source module 310 of fig. 3, and the connection relationship and configuration between the current source module 310 and other components and assemblies in the converter 200 are similar or identical to the connection relationship and configuration between the current source module 310 and other components and assemblies in the converter 200.

Preferably, the second control element 314 may be a Schottky Barrier Diode (SBD). The second regulating element 314 is electrically connected between the voltage regulator V1 and the source current sampling resistor Rcs, that is, the voltage regulator V1 (via the sixth node J6) of the current source module 310 different from fig. 3 is directly electrically connected to the source current sampling resistor Rcs, and the source current sampling resistor Rcs of the current source module 310c is not directly electrically connected to the voltage regulator V1. The remaining elements of the current source module 310c, except for the second control element 314, are similar to or the same as the elements with the same name and number included in the current source module 310 of fig. 3, and are described in detail in the related paragraphs above, so they are not described in detail again.

The value of the source current Isc output by the current source module 310c may be calculated by the following equation:

where Rcs is a resistance value of the source current sampling resistor Rcs, Vbe is a forward voltage drop value Vbe of a silicon PN junction of the first regulation element 312 (e.g., the transistor 312 of fig. 3), and VSBD is a forward voltage drop value of the second regulation element 314(SBD diode). Since a temperature coefficient of the second control element 314 is directly proportional to the Vbe value of the first control element 312, when the Vbe value of the first control element 312 increases, the forward voltage drop VSBD value of the second control element 314 also increases, so that the source current Isc output by the current source module 310c is not affected by the temperature.

Compared to the current source module 310b of the precision voltage parallel integrated circuit 312, the current source module 310c using the transistor and the SBD diode as the two

control elements

312 and 314 may have a slightly lower precision in eliminating the influence of the temperature on the source current Isc, but the manufacturing cost of the current source module 310c is also lower than that of the current source module 310 b.

The start-up control circuit 300 may further include a start-up state determining module 320 for determining whether to shut down the current source module 310 (or the

current source module

310b or 310c) in operation. More specifically, the start-up state determining module 320 is used to control the voltage regulator V1 of the current source module 300 to turn off the current source module 310 in operation when the converter 200 enters the normal operation stage after start-up. Preferably, the activation state determination module 320 includes a switch V3. One terminal of the switch V3 is connected to ground, and the other terminal is electrically connected to the fourth node J4. In one embodiment, the switch V3 is a transistor. The start-up state determining module 320 is electrically connected to a seventh node J7 for receiving an auxiliary-side rectified voltage Vaux.

One end of the isolation diode D1 is electrically connected to the auxiliary-side rectifying diode D11 and the start-up state determining module 320 through a seventh node J7; the other end of the isolation diode D1 is electrically connected to the starting capacitor C1. One end of the auxiliary-side rectifying diode D11 is electrically connected to the start-up state determining module 320 and the auxiliary-side output capacitor C11 through the seventh node J7; the other end of the auxiliary side rectifying diode D11 is electrically connected to the auxiliary winding Laux.

The auxiliary side output capacitor C11 is used to filter the voltage output by the auxiliary winding Laux. The auxiliary winding Laux rectifies the voltage of the starting capacitor C1 by an auxiliary rectifier diode D11, thereby generating the auxiliary rectifier voltage Vaux. The start-up state determining module 320 may determine whether the converter 200 is close to the start-up completion stage according to the received auxiliary side rectified voltage Vaux. In more detail, the start-up state determining module 320 compares the auxiliary-side rectified voltage Vaux (i.e., the voltage of the start-up capacitor C1) with a voltage threshold Vth. Preferably, the voltage threshold Vth is 12 volts.

If the auxiliary-side rectified voltage Vaux is equal to or greater than the voltage threshold Vth, the start-up state determining module 320 may determine that the start-up of the converter 200 is close to being completed, and the output of the start-up state determining module 320 is triggered to be at a low level, so that the gate voltage of the voltage regulator V1 is also forced to be at a low level, and the current source module 310 (or the

current source module

310b or 310c) in operation is turned off; in other words, the current source module 310 is turned on only during the start-up phase of the converter 200, and is turned off during the normal operation phase after the start-up of the converter 200, so that no power loss is caused.

Before the current source module 310 is turned off, the current source module 310 charges the start charger C1, and the start charger C1 also charges the control unit 66 by a small amount at this time, until the control unit 66 has a certain amount of power available to the start charger C1, the start of the converter 200 is also completed, and then enters a normal operation state, at this time, the start state determining module 320 turns off the current source module 310, and the auxiliary winding Laux supplies power to the isolation diode D1, the auxiliary side rectifier diode D11, the start capacitor C1, the auxiliary side output capacitor C11, the control unit 66, and other devices.

The starting control circuit of the converter uses an innovative current source module without using a resistor with high resistance value, so that the converter can be started in a short time, the quick starting required by vehicle equipment is realized, and the requirements on the safety of vehicle use and the requirements of users are further met. In addition, compared to the expensive and hard-to-obtain N-channel depletion MOSFET transistors used in the prior art, the current source module of the present invention is composed of easily-obtained components, such as power transistors (e.g., IBGT transistors or N-channel enhancement MOSFET transistors), gate bias resistors, and the bias resistors for cooperating with each other to set the operating point of the first regulation element, which are cheap, hard to damage, and stable.

The starting control circuit of the converter of the invention can be additionally provided with a starting state judging module which closes the current source module after the converter is started, so that under the normal operation condition after the converter is started, the current source module can not cause any power loss after being closed, thereby improving the overall working efficiency of the converter, and the converter does not need special heat dissipation design and is not damaged, thereby simplifying the design of circuits and equipment and further greatly reducing the manufacturing cost.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A converter comprises a starting capacitor, a control unit and a transformer; the converter is characterized by comprising a starting control circuit, a control unit and a control unit, wherein the starting control circuit is used for regulating and controlling a current for starting the control unit; the starting control circuit comprises a current source module which is electrically connected with the starting capacitor, the control unit and the primary winding of the transformer; the current source module includes:

a voltage regulator;

a first regulatory element;

a source current sampling resistor to cooperate with the first regulation element to adjust a conductivity of the voltage regulator;

a gate bias resistor for providing a gate bias voltage to the voltage regulator;

a plurality of bias resistors for setting an operating point of the first regulating element,

wherein the first regulation element electrically connects the gate bias resistor, the plurality of bias resistors, and the start-up capacitor,

wherein the current source module generates a source current to charge the start capacitor according to a voltage value of the first regulation element and a resistance value of the source current sampling resistor,

the first regulating and controlling element is a precise voltage parallel integrated circuit, and the value of the source current output by the current source module is calculated by the following formula:

where Rcs is the resistance value of the source current sampling resistor and Vreg is the internal reference voltage value of the precision voltage parallel integrated circuit.

2. The converter of claim 1, wherein: the start-up control circuit further comprises a start-up state judgment module for controlling the voltage regulator to shut down the current source module in operation when the converter enters a normal working stage after being started up.

3. The converter of claim 1, wherein: the current source module forms a closed loop control circuit to gradually adjust the source current.

4. The converter of claim 2, wherein: the starting state judging module is used for judging whether to close the current source module in operation according to the received auxiliary side rectified voltage; wherein an auxiliary winding of the transformer rectifies a voltage of the starting capacitor to generate the auxiliary side rectified voltage.

5. The converter of claim 4, wherein: the converter further comprises:

an auxiliary side output capacitor for filtering the voltage output by the auxiliary winding;

and an auxiliary side rectifying diode electrically connected to the auxiliary side output capacitor, the auxiliary winding and the starting state determining module, wherein the auxiliary winding rectifies a voltage of the starting capacitor through the auxiliary side rectifying diode to generate the auxiliary side rectified voltage.

6. The converter of claim 1, wherein: the voltage regulator is an N-channel enhanced metal oxide semiconductor field effect transistor or an insulated gate bipolar transistor.

7. The converter of claim 1, wherein: the plurality of bias resistors includes a base current limiting resistor and a base pull-down resistor.

8. The converter of claim 1, wherein: the plurality of bias resistors include a first voltage dividing resistor and a second voltage dividing resistor.

9. The converter of claim 1, wherein: the input power received by the converter is a high voltage power supply.

10. The converter of claim 1, wherein: the converter is one of the following: a flyback converter, a forward converter, a half-bridge converter or a full-bridge converter.