CN102307006B - Start-up circuit of high-voltage power supply - Google Patents

Abstract

A high-voltage power supply starting circuit belongs to the field of electronic technology. It is characterized in that the input terminal of BR ₁ is respectively connected with the output terminal x of TA and the terminal p of J _1-2D of J ₁ , and the voltage of the output terminal of BR ₁ is applied to the input of U ₁ after passing through C ₁ , R ₃ , VZ ₁ and R ₄ terminal, the collector of the output terminal of U ₁ is connected to the non-inverting input terminal of U ₂ , and connected to the control power supply V _cc through R ₅ , the emitter of the output terminal of U ₁ is connected to the ground of V _cc , and the inverting input terminal of U ₂ is connected to the ground of V cc through R ₇ The ground of V _cc is connected, and connected to the contact J _1-1D via R ₆ , the contact J _1-1 is connected to V _cc , the anode of VD ₂ is connected to the anode of VD ₃ , and connected to the base of V ₁ via R ₁ , V _cc is connected to the anodes of VD ₂ and VD ₃ via R ₈ , the cathode of VD ₂ is connected to the output terminal of U ₂ , and the cathode of VD ₃ is connected to the output terminal V _con of the high-voltage power supply control unit to output control signals. The effect and benefit of the present invention are that the starting circuit is simple, reliable, low in cost, and convenient in design and manufacture.

Description

A high-voltage power supply start-up circuit

technical field

The invention belongs to the field of electronic technology, and relates to a power starting circuit, in particular to a high-voltage power starting circuit applied to a voltage regulating form of an auto-coupling voltage regulator.

Background technique

High-voltage power supply has important applications in many fields. According to the needs of safety and application objects, it is often required (for example, when conducting insulation tests on related materials) that the high-voltage power supply has a "return to zero start" function, that is, the output voltage is required to be stable after the high-voltage power supply is started. Zero or very low, and then gradually increase the voltage according to the test requirements.

At present, based on considerations of application, cost, reliability, etc., many high-voltage power supplies still use auto-voltage regulators for voltage regulation. In order to realize the function of returning to zero for the high-voltage power supply in the form of voltage regulation, known methods include:

One is to adopt a soft start method. Although this method can ensure that the output voltage of the high-voltage power supply is zero when it is just started, due to human negligence, the carbon brush that determines the output voltage of the autovoltage regulator before starting may not be at zero voltage or a very low voltage position, so the high-voltage power supply After starting, the output voltage may rise to a higher voltage soon (its size is determined by the carbon brush position of the auto-transformer before starting), and the zero-returning start function of the high-voltage power supply cannot be reliably realized.

The second is to adopt the method of installing a mechanical travel switch or a button switch with a normally open contact on the corresponding part of the autovoltage regulator (corresponding to the position of the carbon brush when the output voltage of the autovoltage regulator is zero or very low). The principle of this method is shown in Figure 1. It is to connect the normally open contact of the switch ST in series with the starting circuit of the high-voltage power supply. When the carbon brush of the autovoltage regulator is adjusted to a position where the output voltage is zero or very low, Make the normally open contact of the switch ST close, only then press the power start button SB ₂ , under the control of the control signal V _con output from the high-voltage power supply measurement and control unit, the two normally open contacts J ₁ of the relay J _{1 -1H} and J _1-2H (see Figure 2) are closed, and the main power supply circuit of the high-voltage power supply is connected, and the high-voltage power supply can start to work. Although this method can realize the zero-return start function of the high-voltage power supply, it is inconvenient in practice because the designer needs to install a mechanical travel switch or a button switch on the auto-coupling voltage regulator. The size, shape and structure of the controller and the internal layout of the high-voltage power supply controller are often restricted by factors such as fixing methods and spatial locations.

Contents of the invention

The purpose of the present invention is to provide a new type of starting circuit for the high-voltage power supply in the form of voltage regulation by an auto-coupling voltage regulator. , it can ensure that the high-voltage power supply can be started only when the output voltage of the auto-transformer is zero or very low, and the output voltage of the high-voltage power supply is stable at zero or very low after the power supply is started, which can solve the problem of zeroing the high-voltage power supply. Function.

The technical scheme adopted in the present invention is: _a high-voltage power supply _startup circuit _includes a detection circuit and a _control circuit _. Resistors R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , working power supply V _cc , etc., the control circuit consists of diodes VD ₁ , VD ₂ , VD ₃ , triode V ₁ , stop button SB ₁ , start button SB ₂ , The working coil of relay J ₁ , the normally open contact J _1-1H and the normally closed contact J _1-1D of a group of contacts of J ₁ , resistors R ₁ , R ₂ , R ₈ , working power supply V _cc and so on. Its characteristics are: one end of the input end of BR ₁ is connected with the output end x of the auto-transformer TA, the other end of the input end of BR ₁ is connected with the outlet p of the normally closed contact J _1-2D of the relay J ₁ , and the output of BR ₁ The positive pole of the terminal is connected to the positive pole of C ₁ and one end of R ₃ , the negative pole of the output terminal of BR ₁ is connected to the negative pole of C ₁ , the anode of VZ ₁ and one end of R ₄ , the other end of R ₃ is connected to the cathode of VZ ₁ and U ₁ The anode of the input terminal is connected, the cathode of the input terminal of U ₁ is connected with the other end of R ₄ , the collector of the output terminal of U ₁ is connected with the non-inverting input terminal of U ₂ , the collector of the output terminal of U ₁ is connected with the working power supply V _cc via R ₅ , U The emitter of the output terminal ₁ is connected to the ground of V _cc , the inverting input terminal of U ₂ is connected to the ground of V _cc through R ₇ , the inverting input terminal of U ₂ is connected to the contact J _1-1D through R ₆ , and the moving contact Point J _1-1 is connected to V _cc , the anodes of VD ₂ and _{VD 3} are connected to the base of V 1 through R ₁ , V _cc is connected to the anodes of VD ₂ and VD ₃ through R ₈ , and the cathode of VD ₂ is connected to U ₂ The output terminals are connected, and the cathode of VD ₃ is connected with the output terminal of the output control signal V _con of the high-voltage power supply measurement and control unit.

The guiding ideology of the above technical solution is: before the power is started, the normally closed contact J _1-2D of J ₁ is in the closed state, and the output voltage of the auto voltage regulator TA is rectified and filtered by BR ₁ , C ₁ , R ₃ , etc. DC voltage to control the current at the input terminal of U ₁ , and then change the voltage of the collector at the output terminal of U ₁ , and use a comparator composed of U ₂ , R ₅ , R ₆ , and R ₇ to detect the voltage at the collector at the output terminal of U ₂ voltage and give a corresponding signal. When the output voltage of TA is zero voltage or very low, the current at the input terminal of _U1 is very small, and the equivalent resistance at the output terminal of _U1 is very large, so that the voltage at the non-inverting input terminal of _U2 (that is, the voltage at the collector of the output terminal of _U1 ) Greater than the voltage at the inverting input terminal of U ₂ (set by R ₆ and R ₇ through the normally closed contact J _1-1D of J ₁ through the working power supply V _cc ), U ₂ outputs a high-level signal, and U ₂ outputs a high The level signal and V _con are high-level signals after passing through the AND gate formed by VD ₂ , VD ₃ , and R ₈ . At this time, press the power start button SB ₂ , and V ₁ drives J ₁ to work, making J _{1 -1H} and J _1-2H are closed, the main circuit of the high-voltage power supply is connected, the output voltage of the high-voltage power supply is zero or very low voltage, and the zero-return start of the high-voltage power supply is realized; on the contrary, when the output voltage of TA is not very low, U ₂ outputs a low-level signal. At this time, even if SB ₂ is pressed, because the base of V ₁ is at a low level, V ₁ is cut off, and J _1-2H located in the main circuit of the high-voltage power supply is still in the disconnected state, and the high-voltage power supply is not activated. After the high-voltage power supply starts, J _1-1D and J _1-2D of J ₁ become disconnected, the voltage of the inverting input terminal of U ₂ is set to zero, and the voltage of the non-inverting input terminal of U ₂ is much greater than zero (because J _1-2D cuts off the voltage of the input terminal of BR ₁ , so that the equivalent resistance of the output terminal of U ₁ is very large), so the output terminal of U ₂ still maintains the high-level signal when the power supply is started during the high-voltage power supply operation.

The effect and benefits of the present invention are: it is composed of a detection circuit and a control circuit, and it does not need to install a travel switch or a button switch on the auto-coupling voltage regulator, nor does it need to replace the relay in the original starting circuit, so that the auto-coupling voltage regulator can be used. For the high-voltage power supply in the form of voltage regulator, the high-voltage power supply can be started only when the output voltage of the auto-voltage regulator is zero or very low, and the output voltage of the high-voltage power supply is stable at zero or very low after the power supply is started, and the high-voltage power supply can be reliably realized. The reset to zero start function. There is no need to install a limit switch or a button switch on the auto-coupling voltage regulator, and the design and manufacture are convenient. The circuit is simple, the cost is low, and the reliability is high.

Description of drawings

Figure 1 is a starting circuit diagram with a zero-return starting function commonly used in high-voltage power supplies in the form of auto-voltage regulators.

In the figure: ST is the travel switch fixed on the corresponding part of the auto-transformer (corresponding to the position where the output voltage of the auto-transformer is zero or very low); SB ₁ is the stop button of the high-voltage power supply (the contact is normally closed ); SB ₂ is the start button of the high-voltage power supply (the contact is normally open); J _1-1H is the normally open contact of a group of contacts of the relay J ₁ ; J _1-1D is the contact of a group of contacts of the relay J ₁ Normally closed contact; V _con is the control signal output from the high-voltage power supply measurement and control unit. Under normal circumstances, V _con is at a high level. When the high-voltage power supply has an overcurrent or overvoltage fault, V _con is at a low level; HR It is the stop indicator light of the power supply; HG is the start indicator light of the power supply; V _cc is the working power supply.

Figure 2 is a schematic diagram of the main circuit of a high-voltage power supply in the form of voltage regulation by an auto-coupling voltage regulator.

In the figure: TA is a self-coupling voltage regulator, the input and output of TA are A, X and a, x respectively; J _1-2H and J _1-2D are another group of contacts of relay J ₁ in Fig. 1 The normally open contact and the normally closed contact of the point; p is the lead end connected with J _1-2D ; V _con is the control signal output by the high voltage power supply measurement and control unit; HV _out is the high voltage output by the high voltage power supply.

Fig. 3 is a starting circuit diagram of a high-voltage power supply provided by the present invention.

In the figure: x is connected to the output terminal x of the auto-transformer TA in Figure 2; p is connected to the lead-out terminal p of J _1-2D in Figure 2; U ₁ is a photocoupler; U ₂ is an operational amplifier, here as The comparator is used; J _1-1H , J _1-1D and J _1-1 are the normally open contact, normally closed contact and moving contact of a group of contacts of the relay J ₁ respectively; HR is the stop indicator light of the power supply ; HG is the start indicator light of the power supply; V _cc is the working power supply.

Detailed ways

Specific embodiments of the present invention will be described in detail below in conjunction with technical solutions and accompanying drawings.

In a high-voltage power supply start-up circuit shown in Figure 3, it includes a full bridge BR ₁ , capacitor C ₁ , Zener diode VZ ₁ , photocoupler U ₁ , operational amplifier U ₂ , resistors R ₃ , R ₄ , R _5. The detection circuit composed of R ₆ , R ₇ , working power supply V _cc , etc., consists of diodes VD ₁ , VD ₂ , VD ₃ , triode V _{1 , stop button SB 1 ,} start button SB ₂ , working coil of relay J ₁ , A control circuit composed of normally open contacts J _1-1H and normally closed contacts J _1-1D of a group of contacts of J ₁ , resistors R ₁ , R ₂ , R ₈ , and working power supply V _cc . The input terminal of BR ₁ is respectively connected with the output terminal x of the autotransformer TA in the main circuit of the high-voltage power supply and the lead-out terminal p of the normally closed contact J _1-2D of J ₁ , and the output terminal voltage of BR ₁ is passed through C ₁ , R ₃ , VZ ₁ , R ₄ , applied to the input terminal of U ₁ , the normally open contact J _1-2H of another set of contacts of J ₁ is connected in series with the auto-coupling voltage regulator TA of the main circuit of the high-voltage power supply Between the output terminal and the input terminal of the power conversion unit (see FIG. 2 ), the connection relationship among other components is shown in FIG. 3 .

Figure 3 uses the DC voltage rectified and filtered by TA output voltage through BR ₁ , C ₁ , R ₃ , etc. to control the current at the input terminal of U ₁ , and then change the equivalent resistance at the output terminal of U ₁ and the voltage of the collector at the output terminal of U ₁ , using a comparator composed of U ₂ , R ₅ , R ₆ , R _7, etc. to detect the voltage of the collector of the output terminal of U ₂ and give a corresponding signal, which together with V _con controls the conduction or cut-off of V ₁ , and control the high-voltage power supply to start or not through the relevant contacts of _J1 .

Before the high-voltage power supply is started, V ₁ is cut off, J _1-1D and J _1-2D of J ₁ remain closed, the stop indicator HR of the power supply is on, the start indicator HG is off, V _cc passes through J _1-1D and passes through R ₆ and R ₇ divide the voltage, and set a reference voltage greater than 0V for the inverting input terminal of U ₂ used as a comparator. At this time, when the output voltage of TA is zero or very low, the current at the input terminal of U ₁ is very small, and the equivalent resistance at the output terminal of U ₁ is very large, so that the voltage at the non-inverting input terminal of U ₂ (that is, the voltage at the collector of the output terminal of U ₁ Voltage) is greater than the reference voltage of the inverting input terminal of U ₂ , U ₂ outputs a high-level signal, and the high-level signal output by U ₂ and V _con (V _con is high under normal circumstances, when the power supply is overvoltage or overcurrent V _con is low level), after the AND gate formed by VD ₂ , VD ₃ , and R ₈ , it is a high level signal. At this time, press the power start button SB ₂ to drive J ₁ to work by V ₁ to make J _1-1H and J _1-2H are closed, the main circuit of the high-voltage power supply is connected, the output voltage of the high-voltage power supply is zero or very low voltage, and the zero-return start of the high-voltage power supply is realized, the start indicator HG of the power supply is on, and the stop indication The lamp HR goes out; on the contrary, when the output voltage of TA is not very low voltage, U ₂ outputs a low level signal, and the low level signal output by U ₂ and V _con pass through the AND gate formed by VD ₂ , VD ₃ , and R ₈ After that, it is a low-level signal. At this time, even if SB ₂ is pressed, because the base of V ₁ is at a low level, V ₁ is cut off, and J _1-2H located in the main circuit of the high-voltage power supply is still in the disconnected state, and the high-voltage power supply is not activated.

After the high-voltage power supply starts, _J1-1D and _J1-2D of _J1 become disconnected, the voltage of the inverting input terminal of _U2 is set to zero, and the voltage of the non-inverting input terminal of _U2 is much greater than zero (because J _1-2D cut off the voltage of the input terminal of BR ₁ , so that the equivalent resistance of the output terminal of U ₁ is very large), so the output terminal of U ₂ still maintains the high-level signal when the power supply is started during the high-voltage power supply operation, As long as there is no over-current or over-voltage fault in the power supply, the main circuit of the high-voltage power supply is always connected, and the output voltage of the high-voltage power supply can be changed by adjusting the output voltage of TA.

When the high-voltage power supply has faults such as overcurrent or overvoltage, the control signal _Vcon output from the high-voltage power supply measurement and control unit becomes low level, making the base of _V1 very low, _V1 cuts off, and the coil of _J1 loses Working current, J _1-2H , J _1-2H resume disconnected state, the main circuit power supply of the high-voltage power supply is cut off, and the high-voltage power supply stops working.

In Figure 3, VZ ₁ , R ₃ , and R ₄ play the role of voltage regulation and current limitation, ensuring that the current at the input terminal of U ₁ is within the allowable operating range; VD ₂ , VD ₃ form an AND gate, ensuring that only When the output of _con and U ₂ are both at high level, the high-voltage power supply is started. When the power supply has an overvoltage or overcurrent fault, the high-voltage power supply can be turned off in time; the operational amplifier U ₂ is used here as a comparator, which can save Pull-up resistors required by general comparators.

In conjunction with the above, comparing the starting circuit generally used in the high-voltage power supply of the auto-transformer voltage regulation form shown in Fig. The high-voltage power supply starting circuit does not need to install a travel switch or a button switch on the auto-coupling voltage regulator, nor does it need to replace the relay in the original starting circuit, so that the high-voltage power supply in the form of auto-coupling voltage regulator can be guaranteed. The output voltage of the voltage regulator is zero or very low. After the power supply is started, the output voltage of the high-voltage power supply is stable at zero or very low. At the same time, the high-voltage power supply starting circuit provided by the invention is simple, reliable, low in cost, and convenient in design and manufacture.

Claims (1)

1. a high voltage source start-up circuit, comprise testing circuit and control circuit, and testing circuit is by full-bridge rectifier BR ₁, capacitor C ₁, voltage stabilizing didoe VZ ₁, photoelectrical coupler U ₁, operational amplifier U ₂, resistance R ₃, R ₄, R ₅, R ₆, R ₇Consist of, control circuit is by diode VD ₁, VD ₂, VD ₃, triode V ₁, SB stops key ₁, start button SB ₂, relay J ₁Actuating coil, J ₁The normally opened contact J of one group of contact _1-1HAnd normally-closed contact J _1-1D, resistance R ₁, R ₂, R ₈Consist of, it is characterized in that: BR ₁One end of input is connected with the output x of automatic coupling voltage regulator TA, BR ₁The other end of input and relay J ₁Normally-closed contact J _1-2DExit p be connected, BR ₁The positive pole of output with C ₁Positive pole, R ₃An end be connected, BR ₁The negative pole of output with C ₁Negative pole, VZ ₁Anode and R ₄An end be connected, R ₃The other end and VZ ₁Negative electrode, U ₁The anode of input is connected, U ₁The negative electrode of input with R ₄The other end be connected, U ₁The collector electrode of output and U ₂In-phase input end be connected, U ₁The collector electrode warp of output R ₅With working power V _ccBe connected, U ₁The emitter of output and working power V _ccGround be connected, U ₂The inverting input warp R ₇With working power V _ccGround be connected, U ₂The inverting input warp R ₆With contact J _1-1DBe connected, moving contact J _1-1With working power V _ccBe connected, VD ₂And VD ₃The anode warp R ₁With V ₁Base stage is connected, working power V _ccWarp R ₈With VD ₂And VD ₃Anode be connected, VD ₂Negative electrode and U ₂Output be connected, VD ₃Negative electrode and the control signal of high voltage source control unit V _conOutput is connected.

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