The title requires immediate explanation since the term “voltage generator” is not commonly used. However, the term “current generator power supply” is accepted, and in the comparison of the two (in this context), perhaps the term “voltage generator” is more appropriate. By “voltage generator power supply,” we mean a constant voltage or voltage-regulated stabilized power supply.
It is important to compare these two fundamentally different power supply modes because more and more LED lamps are being marketed with replaceable power supplies, meaning they operate with a current generator power supply separate from the lamp. When these fail, users who have never heard of current generator power supplies understandably have completely erroneous ideas about what kind of power supply to buy for their LED if the factory power supply is not available separately.
Current Generator Power Supply:
- Characteristics:
- Provides a constant current regardless of the load.
- The output voltage varies depending on the load resistance.
- Has high internal resistance.
- Acts as a fixed current source.
- Advantages:
- Provides constant current, ideal for constant power demand loads.
- Better withstands load changes.
- Causes less current fluctuation.
- Disadvantages:
- More difficult to implement and control.
- Less efficient than voltage generator power supplies.
Voltage Generator Power Supply:
- Characteristics:
- Provides a constant voltage regardless of the load.
- The output current varies depending on the load resistance.
- Has low internal resistance.
- Acts as a fixed voltage source.
- Advantages:
- Provides stable output voltage, ideal for sensitive electronic devices.
- Easier to implement and control.
- More efficient than current generator power supplies.
- Disadvantages:
- Not ideal for constant power demand loads.
- Can cause more current fluctuations than current generator power supplies.
In summary:
Current generator and voltage generator power supply modes have different advantages and disadvantages. The choice depends on the application’s requirements. For constant current demand, the current generator might be the better choice, while for stable voltage demand, the voltage generator is more favorable.
There are also hybrid power supplies that combine the principles of current generator and voltage generator, aiming to maximize the advantages of both approaches.
What problems might arise if a consumer tries to operate a device with a power supply that does not provide the appropriate current or voltage range for current generator power supplies?
1. If the current demand is greater than what the power supply provides:
- Overcurrent: The consumer exceeds the power supply’s current limit, causing overcurrent. This can lead to the power supply overheating, damage, or even the destruction of the consumer.
- Voltage drop: The power supply cannot maintain the output voltage under increased load, leading to voltage fluctuations or a drop for the consumer. This can cause the consumer to malfunction or shut down.
2. If the current demand is less than what the power supply provides:
- Instability: The power supply’s output current does not match the consumer’s lower current demand, leading to voltage fluctuations or ripple. This can cause the consumer to malfunction.
- Heat generation: The power supply continues to generate maximum current, wasting excess energy and potentially leading to overheating.
3. If the voltage demand is greater than the power supply’s maximum value:
- Damage: The power supply cannot provide the necessary voltage, which can lead to consumer damage.
- Sparking: The voltage difference can cause sparking in the power supply or consumer, posing a fire hazard.
4. If the voltage demand is less than the power supply’s minimum value:
- Operational disturbance: The consumer does not receive the necessary voltage for proper operation, causing malfunctions or shutdowns.
- Overcurrent: The consumer may try to compensate for the missing voltage by drawing increased current from the power supply, leading to overcurrent and power supply damage.
Current generator power supplies are sensitive to changes in the consumer’s current and voltage demands. Demands greater than the power supply’s maximum passing power can lead to overload, damage, and instability, while demands less than the power supply’s capacity can cause operational disturbances and efficiency loss. Proper operation and damage prevention can only be ensured by compatibility between the power supply and the consumer.
What problems might arise when using a voltage-regulated stabilized power supply if a consumer is operated with a power supply that does not provide the appropriate voltage or does not match the current draw?
1. If the current demand is greater than what the power supply provides:
- Overcurrent: The consumer exceeds the power supply’s current limit, causing overcurrent. This can lead to the power supply overheating, damage, or even the destruction of the consumer.
- Voltage drop: The power supply cannot maintain the output voltage under increased load, leading to voltage fluctuations or a drop for the consumer. This can cause the consumer to malfunction or shut down.
2. If the current demand is less than what the power supply provides:
- Stability: Voltage-regulated stabilized power supplies generally provide stable output voltage, making them less sensitive to the consumer’s lower current demand compared to current generator power supplies. Therefore, voltage fluctuations or ripple can be ruled out.
- Efficiency loss: As the power supply continues to generate current, it may waste excess energy due to lack of load, leading to reduced efficiency.
3. If the voltage demand is greater than what the power supply provides:
- Damage: The power supply cannot provide the necessary voltage, which can make the consumer’s operation unstable or non-functional, potentially leading to damage.
- Sparking: The voltage difference can cause sparking in the power supply or consumer, posing a fire hazard.
4. If the voltage demand is less than what the power supply provides:
- Overdrive: Operating at a higher voltage than designed forces the consumer to deliver more power, which can cause overheating, premature failure, or even immediate malfunction.
- Efficiency loss: The power supply continues to generate maximum voltage, wasting excess energy, which leads to reduced efficiency.
Voltage-regulated stabilized power supplies are less sensitive to changes in the consumer’s current demand compared to current generator power supplies. The risk of voltage fluctuation and damage is lower, but efficiency loss can still occur if the consumer’s current or voltage demand significantly deviates from the power supply’s capacity. Ensuring compatibility between the power supply and the consumer is essential for proper operation and to avoid damage.
To prevent damages resulting from improper applications, manufacturers employ certain solutions.
Current generator and voltage generator power supplies are equipped with numerous operational safety and life protection measures to prevent damage from improper use.
General solutions:
- Overcurrent protection: Automatically shuts down the power supply if the output current exceeds the set value, preventing damage to the power supply and the consumer.
- Overvoltage protection: Automatically shuts down the power supply if the output voltage exceeds the set value, preventing damage to the consumer.
- Thermal protection: Automatically shuts down the power supply if the internal temperature exceeds the set value, preventing overheating and damage to the power supply.
- Reverse polarity protection: Prevents damage to the power supply if the output polarity is connected in reverse.
- Filters: Reduce disturbances and noise on the power supply output, improving output voltage stability and consumer operation.
Specific solutions:
Current generator power supplies:
- Current limiting: Adjustable current limit that prevents the consumer from drawing more than the maximum current of the power supply.
- Current backfeed protection: Prevents the consumer from feeding current back into the power supply, which could damage it.
Voltage generator power supplies:
- Voltage regulation: Automatically regulates the output voltage to remain constant even under load changes.
- Short-circuit protection: Automatically shuts down the power supply in the event of a short circuit, preventing damage to the power supply and the consumer.
Additionally, power supplies comply with relevant safety regulations and standards, such as CE, UL, CSA, RoHS, etc.
These are general operational safety and life protection solutions. Specific solutions may vary depending on the type and manufacturer of the power supply. To avoid improper use, it is important to use the power supply only as intended. Do not overload the power supply, do not use it in wet or explosive environments, and do not expose it to physical impacts.
Complete LED light source constructions prefer current generator drive.
In contrast, LED strips predominantly require constant voltage power supply.
– Why is this?
There are several reasons why current-driven LED light sources are more advantageous compared to voltage-driven ones:
- Efficiency:
• Current-driven operation does not require resistors to set the current. This reduces power loss, improving the efficiency of the light source. In voltage-driven LEDs, resistors generate unnecessary heat, leading to additional energy loss.
• Current-driven operation provides consistent current to the LEDs regardless of power supply fluctuations. This results in more uniform light output and a longer LED lifespan. In contrast, the brightness of voltage-driven LEDs can fluctuate with power supply changes, shortening their lifespan. - Stability:
• Current-driven operation ensures more stable performance with less noise and ripple. This results in better light quality and less flicker. Voltage-driven LEDs are more prone to noise and ripple, which can degrade the light quality. - Flexibility:
• Current-driven operation is more flexible in terms of LED configuration. It allows for series and parallel connections with variable current draw, providing greater freedom in light source design. Voltage-driven LEDs are generally only suitable for series connections, have a fixed current draw, and require current-limiting resistors. - Cost-effectiveness:
• Although current-driven driver circuits may initially be more expensive than voltage-driven drivers, their longer lifespan and better efficiency make them more cost-effective in the long run. Voltage-driven LED light sources theoretically need to be replaced more frequently, increasing maintenance costs.
LED strips require stabilized fixed voltage power supply, with current-limiting resistors used on the strip to set the current for the LEDs. These resistors cause power loss in LED strips. These resistors are necessary to set the current through the LEDs. However, the resistors consume excess energy, which converts to heat. This leads to efficiency loss, and inadequate heat dissipation shortens the lifespan of the LEDs. Current-driven operation does not use resistors to set the current. Instead, it uses a circuit to provide constant current to the LEDs, eliminating excess energy loss and increasing efficiency.
Therefore, current-driven operation is more efficient, stable, simpler, and cost-effective than voltage-driven operation. This is why it is preferred in complete LED light source constructions.
Despite all this, LED strips are designed for voltage-regulated stabilized power supply. There are several reasons for this:
- Cost-effectiveness:
• Voltage-driven power supplies are cheaper to manufacture than current-driven power supplies. This results in more affordable LED strip systems for consumers.
• Voltage-driven power supplies require fewer components, simplifying the manufacturing process and reducing the likelihood of defects. - Ease of Installation:
• LED strips are easier to install than current-driven LED strips. You only need to connect the power supply to the strip, and the LEDs automatically receive the correct current. - Compatibility:
• These LED strips are widely compatible with standard 12V or 24V power supplies. This makes it easier to use LED strips in various projects. Current-driven LED strips require power supplies with specific current outputs, limiting compatibility. - Regulability:
• These LED strips are easier to dim, allowing controllers to be completely independent units from the power supplies. Dimming current-driven LEDs is more complicated, and special controllers must be integrated with the current-driven power supplies. - Safety:
• LEDs requiring voltage-regulated stabilized power are safer than current-driven LEDs because they operate at lower voltages, reducing the risk of electric shock.
Therefore, while current-driven LED solutions are more efficient, stable, and flexible in pre-planned LED configurations, fixed-voltage LED strips are much more prevalent due to their simplicity, cost-effectiveness, and compatibility.
Risks of Installing Current-driven Power Supplies
It is often said that for safety reasons, it is forbidden to connect a load to a live current-driven power supply because the voltage at the output of an unloaded current-driven power supply will rise to its maximum range. Thus, when you connect an appropriate current-demanding LED panel, if its voltage requirement is at the lower end of the power supply’s voltage range, it will receive a massive voltage spike, causing immediate failure. Even if the current-driven power supply has the right parameters, never connect a load while it is powered on.
This rationale, while valid from a safety standpoint, is only partially correct. It is true that connecting a load to a live current-driven power supply is not recommended, but it does not always cause immediate failure in the LED panel.
The output voltage of current-driven power supplies indeed settles at the maximum of its voltage range when unloaded. This voltage spike can damage the LED panel if its voltage requirement is at the lower end of the power supply’s range.
However, most current-driven power supplies are equipped with voltage regulators that provide constant voltage under load. This means that if the LED panel has the correct current requirement and its voltage requirement is within the power supply’s range, it will not suffer immediate failure.
Nonetheless, using a low-quality current-driven power supply can still damage the LED panel even if the voltage spike does not cause immediate failure. The cause could be unstable voltage and current provided by the power supply. Unstable voltage and current can lead to overheating in the LEDs, shortening their lifespan and leading to eventual failure.
Therefore, it is crucial to always use a power supply that meets the specifications of the LED panel. The right power supply provides stable voltage and current for the LEDs, which extends their lifespan and ensures safe operation.
On the other hand, such problems cannot occur with a voltage-driven power supply.
The output voltage of a voltage-driven power supply remains constant, and logically, the current is 0 Amps when unloaded. This means that if the load (e.g., LED strip) has the appropriate voltage requirement and its current draw does not exceed the power supply’s maximum current, it can be safely connected to a live voltage-driven power supply.
However, it is important to note that the voltage-driven power supply will not automatically limit the current. This means that if the load’s current draw exceeds the power supply’s maximum current, the power supply can become overloaded and fail. Therefore, it is crucial that the load’s current draw does not exceed the power supply’s maximum current.
Unfortunately, not all modern voltage-regulated power supplies are stabilized.
There are both stabilized and unstabilized voltage-regulated power supplies. Stabilized power supplies provide constant output voltage regardless of input voltage fluctuations. The output voltage of unstabilized power supplies can fluctuate in sync with input voltage changes.
It is highly recommended to use a stabilized power supply for LED strips:
- Fluctuations in the output voltage can damage the LED strip.
- Stabilized power supplies ensure safer operation.
- Stabilized power supplies provide a longer lifespan for the LED strip.
Stabilized voltage-driven power supplies are generally more expensive than unstabilized ones. However, the investment is worthwhile considering the longer lifespan and safer operation of the LED strip.