A device for charging a storage capacitor controlled by a microcontroller

Abstract

This utility model pertains to the field of pulse technology, specifically to devices for charging storage capacitors. The technical result is an increased charging rate for a storage capacitor. A device for charging a storage capacitor controlled by a microcontroller is proposed. The device comprises a voltage multiplier connected to an AC power source via a key device for controlling the charging current and a current-limiting capacitor, as well as a key device control unit. The key device control unit is controlled by a microcontroller, which measures the voltage on the storage capacitor via a voltage divider and is connected via a galvanic isolation unit to a manual control unit and a data bus connected to a control computer. 1 Fig.

Description

[0001] The utility model relates to the field of pulse technology, in particular to devices for charging storage capacitors (SC) used in generators of powerful current pulses, including in emitters of pulsed electromagnetic waves, as sources of electrical energy capable of delivering high power in short periods of time, in particular in installations for electro-pulse processing of metals.

[0002] A device for charging a storage capacitor is known (RU patent No. 2133551), containing an alternating voltage source, a thyristor rectifier-switch with a current-limiting and storage capacitor made in the form of a voltage doubler, an adjustable voltage divider, a comparator, a trigger, a synchronization unit and a clock pulse generator.

[0003] The device's disadvantages include: rigid hardware control logic implemented on analog and basic digital microcircuits, which precludes flexible reconfiguration and adaptation of charging algorithms to various operating conditions; the lack of remote monitoring and integration into automated control systems; and the lack of galvanic isolation between the control and power circuits, which reduces operational safety and increases the risk of control electronics failure during voltage surges.

[0004] A device for charging a capacitive storage device for electrical energy is known (RU patent No. 2218646), containing a rectifier, a generator, a comparator, a pulse amplifier, a precision voltage stabilizer, an amplitude detector, a voltage follower, a reference voltage source and an electronic temperature sensor.

[0005] The disadvantage of this solution is its narrow specialization: the device is optimized for the electrochemical charging processes of batteries and does not take into account the physics of charging capacitive storage devices (capacitors), making it ineffective when used directly with capacitors. Furthermore, the device does not include modern microprocessor control.

[0006] The closest analog of this device is a well-known device for charging a storage capacitor (RU patent No. 2452081), which contains an AC source, a voltage multiplier in the form of a rectifier formed by two valve cells, two current-limiting capacitors, two chokes, a storage capacitor, and a voltage monitoring and phase control unit. The presence of a voltage monitoring and phase control unit allows the operator to influence the charging process of the storage capacitor, interrupting it at the desired voltage, which is why this device was chosen as a prototype.

[0007] A drawback of the device is the limited control system. The voltage monitoring and phase control unit does not allow for complex programs and algorithms for capacitor charging to be programmed using a PC, which hinders full automation. Another drawback of the device is the lack of galvanic isolation between the low-voltage measurement / control circuits and the high-voltage power circuits of the voltage multiplier, which creates a risk of damage to the control equipment due to breakdowns or impulse interference.

[0008] The objective of the utility model is to develop a new device for charging a storage capacitor with the achievement of the following technical result: increasing the charging speed of the storage capacitor by automating the process.

[0009] In particular, this utility model can be used as part of installations for electro-pulse metal processing, including as a component of installations that include an emitter of pulsed electromagnetic waves that generate Foucault currents, which can receive flexible and wide control capabilities in software mode.

[0010] The technical result of the invention is achieved in that the device for charging a storage capacitor controlled by a microcontroller contains a voltage multiplier connected to an AC power source through a key device for controlling the charging current and a current-limiting capacitor, a control unit for the key device, wherein the control unit for the key device is controlled by a microcontroller measuring the voltage on the storage capacitor through a voltage divider and connected through a galvanic isolation unit with a manual control unit and an information bus connected to a control computer.

[0011] Unlike similar devices, this device includes a microcontroller (MC) that controls the key device (KD), enabling the storage capacitor charging process to be controlled using algorithms defined by software running on a control personal computer (PC). Automation eliminates the need for manual control of the storage capacitor charging process, increasing the operating speed of this device and the systems in which it is used.

[0012] The figure shows a schematic diagram of a device for charging a storage capacitor controlled by a microcontroller.

[0013] The device for charging a storage capacitor controlled by a microcontroller contains a key device (KU) 1, having two-way conductivity, connected to the phase line L of an alternating voltage source 2 and to its control unit 3 (CU), having galvanic isolation by the signal and by the power supply circuit. A triac is used as KU 1. The second power terminal of KU 1 is connected to a diode-capacitor voltage multiplier (VM) 4 through a current-limiting capacitor C1 5, which also serves as a capacitive galvanic isolation between KU 1 and VM 4. VM 4 is connected to a storage capacitor 6, connected to a voltage divider consisting of resistors R1 7 and R2 8.

[0014] At the initial moment, the control unit 1 is in a normally closed state, and the phase line L of the AC voltage source is cut off from the voltage multiplier 4. The microcontroller (MC) 9 awaits instructions for execution, which are specified by the control personal computer (PC) 10. For cases where it is impossible to use the PC, for example, due to software problems, the utility model is additionally equipped with a manual control unit (MCU) 11.

[0015] In this case, for the purposes of safe use, the information bus 12 (IB) from the PC 10 and the BRU 11 are connected to the MK 9 through the galvanic isolation device (GID) 13.

[0016] We will describe the operation of the storage capacitor charging device in manual control mode. Initially, the KU 1 is normally closed, and the phase line L of the AC voltage source is cut off from the voltage multiplier. The BRU 11 is a combination of an encoder with a button and a liquid crystal display. Using the encoder, the operator can directly set the desired voltage value to which the storage capacitor bank should be charged, without using the PC 10, monitoring this value displayed on the display. This value is first converted into units measured by the ADC, taking into account the voltage divider ratio, consisting of high-resistance resistors R1 7 and R2 8 connected in series, and is stored by the MK 9 as a threshold value. The voltage multiplicity, taking into account the divider parameters, is easily set when programming MK 9. Then, by pressing the encoder button, the operator gives the command to charge, and MK 9 sends a signal to BU 3 to open KU 1.When the control unit 1 opens, closing the phase line L of the AC voltage source with the control unit 4 through capacitor C1 5, the storage capacitor begins to charge from the control unit 4 output. The voltage drop across resistor R2 8, directly proportional to the voltage across the capacitor, is fed to the analog input of MK 9, which measures this voltage in ADC units and compares it with the threshold value. The ADC built into MK 9 operates in this continuous mode, meaning a new voltage measurement begins immediately after the previous one. Upon completion of each measurement, a program interrupt is performed to compare the measured and threshold values. When the comparison condition is met,

[0017]

[0018] MK 9 commands BU 3 to turn off KU 1, and the charging of the storage capacitor ceases. This signaling procedure takes approximately 3 MK 9 cycles, which corresponds to approximately 0.2 µs. However, the ADC operating frequency is approximately 9 kS / s, which corresponds to a delay time of 0.11 ms. Since the shutdown signal generation rate is much higher than the ADC sampling rate, MK 9's response speed to exceeding the threshold is approximately equal to the ADC sampling rate.

[0019] Next, we will describe the device's operation in software control mode. MK 9 switches to software control mode upon receiving a corresponding command from PC 10. The program running on PC 10 can, according to a preset algorithm, transmit the required threshold value to MK 9, which in turn transmits information to PC 10 about its readiness to begin charging. When a charge command is received from PC 10, MK 9 transmits this command to BU 3, which activates KU 1, and charging of the storage capacitor begins. Voltage comparison and deactivation of KU 1 upon reaching the specified voltage value occurs in the same way as in manual mode. MK 9 also transmits voltage values ​​to PC 10 for the purpose of logging and monitoring the charging process by the operator. Upon completion of charging, MK 9 transmits information to PC 10 about the completion of the charging process.

[0020] The UGR 13 protects the operator, BRU 11, ISH 12, and PK 10 from high voltage from the storage capacitor in the event of an emergency, which could damage the equipment or shock the operator. The UGR 13 is located between the MK 9 and ISH 12 with the BRU 11, since galvanic isolation of digital signals is much simpler and less expensive than galvanic isolation of analog signals. In other words, the MK is less expensive than analog signal isolation devices, such as isolation amplifiers, and in the event of an emergency, only the MK will fail.

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