1. Constant current regulation
When the load changes, a regulated power supply needs to adjust its output voltage to maintain a constant output current. Utilizing the principle of negative feedback, the regulated power supply can monitor changes in load current and automatically adjust the output voltage to maintain the load.
This ensures a stable operating state. Therefore, this regulation method is called constant current regulation.
2. Constant pressure regulation
In constant voltage regulation mode, the regulated power supply automatically adjusts the output current to maintain a constant output voltage. When the load current changes, the constant voltage regulated power supply automatically adjusts the output current to maintain a constant output voltage.
In constant voltage regulation mode, the load current cannot exceed the set current value.
3. Constant power regulation
In constant power regulation mode, the regulated power supply adaptively adjusts its output power based on the load current and load voltage. When the load current or load resistance changes, the regulated power supply automatically adjusts its operating power accordingly.
The magnitude of voltage and current under operating conditions.
Generally, constant current regulation is suitable for applications where the power supply needs to maintain a certain current output; constant voltage regulation is suitable for applications where the power supply needs to maintain a certain voltage output; and constant power regulation is suitable for applications where the load demand for both current and voltage changes simultaneously.
Different adjustment modes are suitable for different application scenarios, so when selecting a regulated power supply, it is necessary to choose the most appropriate adjustment mode according to the actual needs.
In summary, adjustable voltage regulators primarily employ three regulation modes: constant current regulation, constant voltage regulation, and constant power regulation. By using different regulation modes, the voltage regulator can automatically monitor the load current, input voltage, and load voltage.
It automatically adjusts the output voltage and current to maintain a stable power output, making it suitable for power supply to various devices and components.
An adjustable power supply is a power device capable of providing stable output voltage and current. Its current regulation is achieved through a series of electronic circuits and control algorithms. The principle of an adjustable power supply is to adjust the output voltage or current by changing the output voltage or current. Specifically, an adjustable power supply typically contains a control circuit that adjusts the output voltage or current based on a set adjustment signal or feedback signal. The control circuit can use various techniques and algorithms to achieve regulation, such as pulse width modulation (PWM) and pulse frequency modulation (PFM).
The output voltage or current of an adjustable power supply can be controlled by an external regulator or microcontroller. The regulator or microcontroller can set a target voltage or current value and compare it with the actual output voltage or current. Based on the comparison result, the regulator or microcontroller outputs a control signal that adjusts the output voltage or current of the adjustable power supply to achieve the target value.
In addition, adjustable power supplies may include protection circuits such as overcurrent protection and overvoltage protection to ensure the safety of the power supply and the powered equipment. When the output current or voltage of the power supply exceeds the safe range, the protection circuit will trigger the corresponding protection mechanism, such as cutting off the power supply output or reducing the output voltage, to prevent damage to the equipment caused by excessive current or voltage.
The current regulation of an adjustable power supply can be mainly divided into the following steps:
1. Input Signal Acquisition: The current regulation system of an adjustable power supply first needs to acquire the output current signal of the power supply through an acquisition circuit. These signals can be analog or digital, depending on the design and implementation of the adjustable power supply.
2. Signal Processing: The acquired current signal will be processed by signal processing circuitry, including operations such as amplification, filtering, and comparison. This processing is a preliminary step to facilitate subsequent adjustment and control.
3. Adjustment Circuit: The adjustment circuit is the core component of the adjustable power supply. It compares the acquired current signal with a preset reference value and generates an adjustment signal. The adjustment signal is usually a control voltage or control current used to control the output current of the adjustable power supply.
4. Power Device Control: The power devices (such as transistors and MOSFETs) in an adjustable power supply are used to control the output current. The regulating signal generated by the regulating circuit adjusts the output current by controlling the switching state of the power devices. Specifically, the regulating signal controls the on and off times of the power devices, thereby changing the magnitude of the output current.
5. Feedback Control Loop: Adjustable power supplies typically include a feedback control loop for real-time monitoring and regulation of the output current. This loop can be either an open-loop or closed-loop control system, chosen based on specific application requirements. In an open-loop control system, the regulating signal directly controls the output current; in a closed-loop control system, the regulating signal is adjusted in real-time based on the feedback output current to ensure stability and accuracy of the output current.
6. Protection Circuits: To protect the adjustable power supply and the powered equipment, the adjustable power supply usually includes some protection circuits (such as overcurrent protection, overvoltage protection, etc.). When the output current exceeds the preset safe range, the protection circuit will trigger the corresponding protection mechanism, such as cutting off the switching state of the power device or reducing the output voltage, to prevent damage to the equipment caused by excessive current or voltage.
In summary, the current regulation of an adjustable power supply is achieved through multiple stages, including acquiring the output current signal, processing the signal, comparison and adjustment, controlling the switching state of power devices, feedback control, and protection circuits. These stages work together to ensure that the adjustable power supply can provide a stable and reliable output current to meet the needs of various application scenarios. In practical applications, it is necessary to select a suitable adjustable power supply based on specific requirements, considering its performance parameters, accuracy, stability, and other requirements. Furthermore, it is essential to pay attention to the operating environment and conditions of the adjustable power supply, and to comply with relevant safety regulations and operating procedures to ensure its normal operation and safety.
The problem likely concerns so-called constant voltage and constant current sources, which can be adjusted based on current and voltage. However, the output voltage and output current must be set separately.
For example, we want to set the output to 12.6V 1.8A:
During operation, please first turn on the power switch and test the no-load voltage. The digital display and two buttons are used to display and adjust the output voltage value. One of the two knobs is for coarse setting, and the other is for fine adjustment. Rotating both knobs should allow the voltage to change continuously from 0 to the maximum value. After confirming that the voltage regulation function is normal, you can adjust the current in the next step.
When adjusting the current, the output terminals must be short-circuited. To avoid power supply failure, first reduce the voltage to approximately 2V (but not to 0V, otherwise no current will be output), then short-circuit the power supply's output terminals. At this point, the voltmeter reading will drop sharply, approaching zero volts, and the ammeter will display the current value. Then, adjust the current to 1.8A using the two current regulators on the right. Next, disconnect the positive and negative terminals of the output connector to end the short-circuit state. At this point, the current will disappear, and the voltage will return to its pre-adjustment state.
The next step in adjusting the tension is relatively simple. Just adjust the two rotary knobs to set the voltage to 12.6V.
If the current and voltage still cannot be adjusted after following the above steps, it indicates a power supply malfunction. Excessive wear of the potentiometer is common and can be resolved by replacing it with a component of the same specification. If other errors exist, it becomes more complex and can only be analyzed on a case-by-case basis.
To clarify, this type of power supply has the capability to achieve either constant current or constant voltage. This is not a malfunction of the power supply itself, but rather determined by Ohm's Law. For example, with the 12.6V and 1.8A listed above, when the load connected to the power supply is low and the current does not reach 1.8A, the power supply output is in a constant voltage state. The voltage remains constant from 0 to 1.8A and 12.6V, and the current varies with the load, but a constant current cannot be achieved.
If we want to further increase the output voltage, you'll find that the voltage cannot be increased when the current reaches 1.8A. This is because the power supply enters a constant current state at this point.
However, as the charging power increases, the current will exceed 1.8A, for example, greater than or equal to 1.8A. By connecting a high-performance 6Ω resistor, according to Ohm's law U/R = 1, 12.6 V ÷ 6Ω = 2.1 A. Since the current is set to 1.8 A, the power supply's output voltage becomes active at 10.8 V (1.8 A × 6Ω). This is reduced to meet the set current requirement. This shows that it is impossible to obtain constant current and constant voltage simultaneously. When the current is constant, the voltage is not constant, and when the voltage is constant, the current is not constant.
This constant current function is very useful when measuring LED light sources. For example, when measuring a 1W LED chip, the current can be set to 0.3A and the voltage to 4-5V (slightly above VF). If the voltmeter reading is 3.25V, this is the VF value of the LED chip. It is convenient to classify and filter light sources or LED chips.
When the 220V power supply is normal, zero current indicates a power supply fault. Often, a long adjustment time for an adjustable potentiometer can cause poor contact. In this case, replace it with a new one. If the problem persists, the voltage regulator is faulty, and the voltage stabilizing circuit needs adjustment.
Jishili Electronics (Suzhou) Co., Ltd. is dedicated to the research and application of power electronic conversion technology. It is a professional manufacturer and solution provider of products such as frequency converters, DC power supplies, AC loads, DC loads, regenerative electronic loads, regenerative grid simulators, battery simulators, charging pile test loads, photovoltaic inverter test equipment, new energy motor and electronic control test power supplies and automated test systems. It is a high-tech enterprise in China with core technologies in power supply and test system automation.
