Overvoltage setting circuit of direct-current high-voltage generator

Abstract

The invention relates to an overvoltage setting circuit of a direct-current high-voltage generator, which comprises a direct-current high-voltage generating circuit and a direct-current high-voltage setting circuit, and is characterized in that the direct-current high-voltage generating circuit comprises a control chip, an inversion driving circuit and a voltage doubling circuit; the direct-current high-voltage setting circuit comprises a digital potentiometer voltage setting circuit, a voltage comparator and a trigger; the overvoltage protection circuit has the advantages of reasonable structure, overvoltage protection, automatic circuit setting and equipment safety protection.

Description

Technical Field

[0001] The invention belongs to the technical field of measuring high-voltage electrical equipment, and in particular relates to an overvoltage setting circuit for a direct current high-voltage generator. Background Art

[0002] The overvoltage setting of the DC high voltage generator in the DC withstand voltage test is a relay protection technology. In the power test, any test product (such as lightning arrester, generator, etc.) has a certain withstand voltage limit. When doing power test, according to the test procedures, the voltage level applied to the test product is lower than this limit voltage. If during the test, due to human error, electromagnetic interference or machine failure, the output voltage of the DC generator exceeds the test product limit voltage, the test product will be damaged. The test failure is not due to the quality of the test product, but the test system exceeds the test product limit voltage. Therefore, the overvoltage setting is set in the high voltage test. In the test, it is a very important protection measure to protect the test product and the test equipment. The working process of overvoltage setting in the DC withstand voltage test is as follows: 1. First, according to the test voltage level of the test product set in the DC test, and the percentage of the test voltage level allowed to exceed the limit overvoltage coefficient in the power test regulations, the overvoltage setting voltage value to be set is obtained; 2. During the test, in the process of boosting the test product and in the process of stabilizing the voltage after reaching the set voltage, once the output voltage of the DC high-voltage generator exceeds the overvoltage setting value to be set, the relay protection circuit will take effect to protect the test product and the test equipment; Some of the existing DC high voltage generators do not have overvoltage setting relay protection measures, and some even have the following problems: 1. The software handles overvoltage setting, but sometimes it is too late to handle it. Some products rely on software to judge and control overvoltage setting. When the overvoltage setting value is exceeded, the software controls the output voltage of the DC high-voltage generator to return to zero. This design method has a slow setting response. When the overvoltage is not high, it can be properly handled. When the high voltage rushes to a very high level, the software does not have time to react and cannot be handled in time, causing damage to the equipment; 2. Hardware processing overvoltage setting, instantaneous cutting off of high voltage, easily forms a large counter-attack voltage. Some products have hardware overvoltage control circuits. When the voltage exceeds the overvoltage setting value, the hardware control circuit instantly cuts off the DC high-voltage generator input circuit, thereby instantly cutting off the high voltage. This design simplifies the voltage setting process. The voltage suddenly returns to zero from high voltage, which will cause a large counter-attack voltage and may damage the test system. Therefore, it is very necessary to provide a DC high-voltage generator overvoltage setting circuit with a reasonable structure, overvoltage protection circuit, automatic circuit setting, and equipment safety protection. Summary of the invention

[0003] 1. Technical issues In view of the above-mentioned existing technical status, this application mainly addresses the following technical problems: 1. The existing software control design has slow setting response. When the high pressure surges very high, the software cannot react in time and cannot handle it in time, causing equipment damage; 2. The existing hardware overvoltage control circuit lacks a voltage setting process. The voltage suddenly returns to zero from high voltage, which will cause a large counter-voltage and may damage the high voltage system.

[0004] (II) Technical solution The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a DC high voltage generator overvoltage setting circuit with a reasonable structure, an overvoltage protection circuit, automatic circuit setting, and protection of equipment safety.

[0005] The object of the present invention is achieved as follows: a DC high-voltage generator overvoltage setting circuit, which includes a DC high-voltage generating circuit and a DC high-voltage setting circuit, the DC high-voltage generating circuit includes a control chip, an inverter drive circuit and a voltage doubling circuit; the DC high-voltage setting circuit includes a digital potentiometer setting voltage circuit, a voltage comparator and a trigger.

[0006] Furthermore, the input end of the control chip is connected to the voltage regulation input circuit, and the output end is connected to the input end of the inverter drive circuit. The output end of the inverter drive circuit is connected to the input end of the voltage doubler circuit, and the output end of the voltage doubler circuit outputs a DC high voltage.

[0007] Furthermore, the control chip adopts a TL494 switching power supply pulse width modulation control chip.

[0008] Furthermore, the DC high voltage generating circuit and the DC high voltage setting circuit are connected via a high voltage sampling circuit.

[0009] Furthermore, the input end of the high voltage sampling circuit is connected to the DC high voltage output by the output end of the voltage doubler circuit, and the output end of the high voltage sampling circuit is connected to the “-” end (inverting input end) of the voltage comparator.

[0010] Furthermore, the “+” terminal (non-inverting input terminal) of the voltage comparator is connected to the digital potentiometer setting voltage circuit, and the output terminal of the voltage comparator is connected to the trigger terminal of the trigger.

[0011] Furthermore, the DC high voltage setting circuit also includes a diode D, a capacitor C and a resistor R.

[0012] Furthermore, one end of the resistor R is connected to the output end of the trigger, and the other end is connected to the cathode of the diode D; the anode of the diode D is connected to the voltage regulation input circuit; the anode of the capacitor C is connected to the resistor R, and the cathode is grounded.

[0013] Furthermore, the digital potentiometer setting voltage circuit is connected to the system main control microcontroller, and the system main control microcontroller sets the set voltage value, adjusts the resistance of the digital potentiometer, and obtains a reference voltage at the "-" end (inverting input end) of the voltage comparator.

[0014] (III) Beneficial effects 1. The circuit of the present invention is an overvoltage protection circuit during the DC boost process, that is, when the voltage exceeds the set "overvoltage setting value", the circuit automatically adjusts and the output gradually returns to zero, thereby protecting the safety of the test product and the equipment; 2. Determine whether the output voltage of the DC high voltage generator exceeds the overvoltage setting value, which is completed by "high voltage sampling", "digital potentiometer setting voltage" and "voltage comparator"; 3. Once overvoltage setting is required, the "trigger" flips, and the output terminal instantly changes from high level to low level. However, due to the existence of the discharge buffer circuit, the "voltage adjustment input" of the "TL494" can only be slowly reduced to zero, so the output high voltage can only be slowly reduced to zero; 4. Since the high voltage drops slowly, du / dt is much smaller than the instantaneous drop of high voltage, so the counter-attack voltage is much smaller, thus protecting the safety of equipment and personnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a circuit diagram of the present invention. DETAILED DESCRIPTION

[0016] The present invention combines the characteristics of software processing and hardware processing of overvoltage setting to find a most effective way to process overvoltage setting, that is, to adopt a hardware overvoltage setting control method and solve the weaknesses of the hardware processing method at the same time, thereby effectively solving the overvoltage setting problem.

[0017] The present invention is further described below in conjunction with embodiments and / or drawings. Example

[0018] like Figure 1 As shown, a DC high voltage generator overvoltage setting circuit includes a DC high voltage generating circuit and a DC high voltage setting circuit. The DC high voltage generating circuit includes a control chip, an inverter drive circuit and a voltage doubling circuit; the DC high voltage setting circuit includes a digital potentiometer setting voltage circuit, a voltage comparator and a trigger.

[0019] The input end of the control chip is connected to the voltage regulation input circuit, and the output end is connected to the input end of the inverter drive circuit. The output end of the inverter drive circuit is connected to the input end of the voltage doubler circuit, and the output end of the voltage doubler circuit outputs a DC high voltage.

[0020] The control chip adopts a TL494 switching power supply pulse width modulation control chip.

[0021] In the present invention, the generation of DC high voltage: Figure 1 The TL494 is a switching power supply pulse width modulation (PWM) control chip. The "voltage regulation input" in the figure is a DC level. The size of this level determines the amplitude of the PWM wave output by the TL494. The PWM wave outputs a DC high voltage through the "inverter drive circuit" and the "voltage doubler circuit". The amplitude of the PWM wave output by the TL494 determines the amplitude of the output DC high voltage. Therefore, adjusting the "voltage regulation input" will adjust the output DC high voltage.

[0022] The DC high voltage generating circuit and the DC high voltage setting circuit are connected via a high voltage sampling circuit.

[0023] The present invention is an overvoltage setting circuit for a DC high voltage generator. In use, the circuit of the present invention is an overvoltage protection circuit during the DC boosting process, that is, when the voltage exceeds the set "overvoltage setting value", the circuit automatically adjusts, and the output gradually returns to zero, thereby protecting the safety of the test product and the equipment. The present invention has the advantages of reasonable structure, overvoltage protection circuit, automatic circuit adjustment, and equipment safety protection. Example

[0024] like Figure 1 As shown, a DC high voltage generator overvoltage setting circuit includes a DC high voltage generating circuit and a DC high voltage setting circuit, and is characterized in that: the DC high voltage generating circuit includes a control chip, an inverter drive circuit and a voltage doubling circuit; the DC high voltage setting circuit includes a digital potentiometer setting voltage circuit, a voltage comparator and a trigger.

[0025] The DC high voltage generating circuit and the DC high voltage setting circuit are connected via a high voltage sampling circuit.

[0026] The input end of the high-voltage sampling circuit is connected to the DC high-voltage voltage output by the output end of the voltage doubler circuit, and the output end of the high-voltage sampling circuit is connected to the “-” end (inverting input end) of the voltage comparator.

[0027] The “+” terminal (non-inverting input terminal) of the voltage comparator is connected to the digital potentiometer setting voltage circuit, and the output terminal of the voltage comparator is connected to the trigger terminal of the trigger.

[0028] The DC high voltage setting circuit also includes a diode D, a capacitor C and a resistor R.

[0029] One end of the resistor R is connected to the output end of the trigger, and the other end is connected to the cathode of the diode D; the anode of the diode D is connected to the voltage regulation input circuit; the anode of the capacitor C is connected to the resistor R, and the cathode is grounded.

[0030] The digital potentiometer voltage setting circuit is connected to the system main control microcontroller, and the system main control microcontroller sets the set voltage value, adjusts the resistance of the digital potentiometer, and obtains a reference voltage at the "-" end (inverting input end) of the voltage comparator.

[0031] In the present invention, the principle of circuit voltage regulation is: ①Triggering of the setting process: Figure 1 The "digital potentiometer setting voltage" is used as the "-" end voltage of the "voltage comparator". The DC high voltage output by the system is passed through the "high voltage sampling circuit" to obtain a low voltage, which is compared with the voltage at the "-" end. Once the "+" end voltage of the "voltage comparator" is greater than the "-" end voltage, the output level of the "voltage comparator" will flip, thereby adjusting the circuit; the "digital potentiometer setting voltage" is adjusted by the system main control microcontroller according to the set voltage value set by the software, and a reference voltage is obtained at the "-" end of the "voltage comparator".

[0032] ② Setting process: Under normal working conditions, the "output end" of the "trigger" is at a high level, which is higher than the "voltage regulation input" voltage, and forms a reverse voltage on the diode "D". Therefore, the high level of the "output end" will not affect the entire boost process of the system; once the output DC high voltage is higher than the setting voltage set by the software, that is, the "+" end voltage of the "voltage comparator" is greater than the "-" end voltage, the "voltage comparator" output level flips to a low level of 0 voltage, which will pull down the cathode voltage of the diode "D". Due to the existence of resistor R, the charge of capacitor "C" is discharged through resistor "R" at a high level and gradually returns to 0 level, clamping the "voltage regulation input" voltage to a low level, so the system output high voltage gradually returns to zero; the time for the system output high voltage to return to zero voltage from the setting voltage depends on the discharge time of capacitor "C", and the discharge time depends on the size of the product of capacitor "C" and resistor "R".

[0033] The present invention is an overvoltage setting circuit for a DC high voltage generator. In use, the circuit of the present invention is an overvoltage protection circuit during the DC boosting process, that is, when the voltage exceeds the set "overvoltage setting value", the circuit automatically adjusts, and the output gradually returns to zero, thereby protecting the safety of the test product and the equipment. The present invention has the advantages of reasonable structure, overvoltage protection circuit, automatic circuit adjustment, and equipment safety protection.

Claims

1. A DC high voltage generator overvoltage setting circuit, comprising a DC high voltage generating circuit and a DC high voltage setting circuit, characterized in that: The DC high voltage generating circuit includes a control chip, an inverter driving circuit and a voltage doubling circuit; the DC high voltage setting circuit includes a digital potentiometer voltage setting circuit, a voltage comparator and a trigger.

2. A DC high voltage generator overvoltage setting circuit as claimed in claim 1, characterized in that: The input end of the control chip is connected to the voltage regulation input circuit, and the output end is connected to the input end of the inverter drive circuit. The output end of the inverter drive circuit is connected to the input end of the voltage doubler circuit, and the output end of the voltage doubler circuit outputs a DC high voltage.

3. A DC high voltage generator overvoltage setting circuit as claimed in claim 2, characterized in that: The control chip adopts the TL494 switching power supply pulse width modulation control chip.

4. A DC high voltage generator overvoltage setting circuit as claimed in claim 1, characterized in that: The DC high voltage generating circuit and the DC high voltage setting circuit are connected via a high voltage sampling circuit.

5. A DC high voltage generator overvoltage setting circuit as claimed in claim 4, characterized in that: The input end of the high-voltage sampling circuit is connected to the DC high-voltage voltage output by the output end of the voltage doubling circuit, and the output end of the high-voltage sampling circuit is connected to the "-" end of the voltage comparator.

6. A DC high voltage generator overvoltage setting circuit as claimed in claim 5, characterized in that: The “+” end of the voltage comparator is connected to the digital potentiometer setting voltage circuit, and the output end of the voltage comparator is connected to the trigger end of the trigger.

7. A DC high voltage generator overvoltage setting circuit as claimed in claim 6, characterized in that: The DC high voltage setting circuit also includes a diode D, a capacitor C and a resistor R.

8. A DC high voltage generator overvoltage setting circuit as claimed in claim 7, characterized in that: One end of the resistor R is connected to the output end of the trigger, and the other end is connected to the cathode of the diode D; the anode of the diode D is connected to the voltage regulation input circuit; the anode of the capacitor C is connected to the resistor R, and the cathode is grounded.

9. A DC high voltage generator overvoltage setting circuit as claimed in claim 6, characterized in that: The digital potentiometer voltage setting circuit is connected to the system main control microcontroller, and the system main control microcontroller sets the set voltage value, adjusts the resistance of the digital potentiometer, and obtains a reference voltage at the "-" end of the voltage comparator.

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