UF Capacitors DC Link Film Capacitors are metallized polypropylene (MKP) capacitors designed for DC bus filtering, energy storage and ripple-current handling in power electronic systems.

Compared with general-purpose film capacitors, DC link capacitors are designed to operate under much higher DC voltage, ripple current and transient stress. They are commonly installed across the intermediate DC bus between a rectifier or DC source and the inverter switching stage, where they help stabilize the DC-link voltage, absorb ripple current and provide short-term energy to the power conversion circuit.

UF Capacitors supplies TDA-series DC-link film capacitors across approximately 450VDC to 1200VDC. The current UF catalog lists a capacitance range of 1.0µF to 170µF, ±5% or ±10% tolerance, and an operating temperature range of -40°C to +105°C. Standard parts use metallized polypropylene film in a plastic box with 2-pin or 4-pin tinned-copper lead configurations.

 

What Is a DC Link Capacitor?

A DC link capacitor, also called a DC bus capacitor, is connected across the intermediate DC bus of a power converter.

A typical power-conversion path can be simplified as:

AC / DC Source  →  Rectifier  →  DC Link Capacitor  →  Inverter  →  Motor / Grid / Load

The DC link capacitor performs several important functions:

 

• Smooths DC-bus voltage fluctuations.
• Absorbs high-frequency ripple current generated by switching devices.
• Supplies short-duration energy during load transients.
• Helps reduce voltage spikes and electrical stress on IGBTs, MOSFETs and SiC power modules.
• Maintains a more stable DC voltage between the input and inverter stages.

Because the capacitor continuously handles ripple current and high voltage, DC-link applications must be selected by more than capacitance and voltage alone. ESR, ESL, ripple-current capability, thermal performance, dielectric construction, mounting and lifetime all matter.

 

Key Features of UF DC Link Film Capacitors

 

Metallized Polypropylene Dielectric

UF TDA DC-link capacitors use metallized polypropylene film. Polypropylene offers low dielectric loss and stable electrical behavior, making it suitable for high-voltage and high-ripple-current DC bus applications.

Self-Healing Construction

Metallized film technology provides self-healing behavior. A localized dielectric breakdown can clear a small metallized area rather than immediately causing a catastrophic short circuit.

Low Loss and High Ripple-Current Capability

The UF TDA datasheet positions the series for high ripple current and low-loss operation. Lower ESR helps reduce internal heating when the capacitor carries substantial RMS ripple current. The exact ESR and current capability depend on the selected capacitance, voltage, case size and part number.

450VDC to 1200VDC Product Range

The current UF TDA catalog specifies a 450VDC to 1200VDC voltage range. This allows the same product family to serve a broad range of industrial converter and inverter designs.

High-Temperature Operation

The published TDA operating-temperature range is -40°C to +105°C. UF notes voltage derating above 85°C, so engineers should evaluate actual hotspot and ambient conditions rather than using the maximum temperature as a continuous full-voltage operating point.

2-Pin and 4-Pin Configurations

UF TDA DC-link capacitors are available in 2-pin and 4-pin box configurations. The correct lead arrangement should be selected according to current handling, PCB layout, mechanical support and the original component footprint.

 

Typical UF DC Link Film Capacitor Specifications

 

Parameter	Typical UF TDA Series Data
Dielectric	Metallized polypropylene film
Voltage Range	450VDC to 1200VDC
Capacitance Range	1.0µF to 170µF
Capacitance Tolerance	±5% or ±10% at 25°C
Operating Temperature	-40°C to +105°C
Dissipation Factor	≤0.002 at 1kHz for C ≤20µF; ≤0.003 at 1kHz for C >20µF
Construction	Plastic box, epoxy encapsulation
Lead Options	2-pin or 4-pin tinned copper wire
Key Characteristics	Self-healing, high capacitance density, high ripple current, low loss, high contact reliability
Typical Applications	DC link, DC filtering, frequency converters, industrial power supplies, solar inverters, energy storage

 

DC Link Capacitor Applications

 

Solar and Photovoltaic Inverters

In a solar inverter, the DC link capacitor is positioned on the intermediate DC bus between the PV-side conversion stage and the inverter bridge. It helps stabilize DC voltage, filter switching ripple and support transient energy before the inverter converts DC power into AC.

Frequency Inverters and Variable Frequency Drives

Industrial VFDs and frequency converters use DC-link capacitors between the rectifier and inverter stages. The capacitor must withstand repetitive ripple current, high DC bus voltage and switching transients generated by IGBT, MOSFET or SiC devices.

Industrial Power Supplies

High-power switch-mode power supplies and industrial power-conversion systems use DC link capacitors for intermediate-bus filtering and energy storage. Typical requirements include high voltage, low loss, high ripple-current capability and long-term thermal stability.

Wind Power and Energy-Storage Converters

Wind-power converters and energy-storage power-conversion systems experience changing power flow and demanding electrical conditions. DC-link film capacitors help stabilize the intermediate bus and manage ripple energy between conversion stages.

EV and High-Power Charging Electronics

DC-link film-capacitor technology is also widely used in EV traction inverters, onboard chargers and high-power charging equipment where high voltage, ripple-current capability and low-inductance construction are important. Qualification for automotive use, however, depends on the exact part and required certification.

 

How to Select a DC Link Film Capacitor

 

1. Rated DC Voltage

Select sufficient margin above the normal DC-bus voltage and verify transient or repetitive peak conditions. Do not select a DC-link capacitor only from the nominal system voltage.

2. Capacitance

Required capacitance depends on allowable bus ripple, converter power, topology, load transient behavior and switching conditions.

3. RMS Ripple Current

Ripple current is one of the most important selection parameters. The actual harmonic spectrum and RMS current should be compared with the part's thermal and current limits.

4. ESR and Internal Heating

Capacitor heating increases with ripple current and ESR. A useful engineering relationship is P ≈ I²R, but the full thermal design should use the manufacturer's data and actual harmonic spectrum.

5. Operating Temperature

Ambient temperature, airflow, spacing and internal hotspot temperature affect life and allowable voltage. Apply the published derating guidance above 85°C.

6. ESL and Terminal Layout

Parasitic inductance influences high-frequency transient behavior. Pin layout, loop area and busbar/PCB geometry matter in fast-switching power electronics.

7. Mechanical Dimensions

Check L × W × H, pin pitch, terminal count, lead length, PCB clearance and vibration/mechanical requirements.

 

Current UF DC Link Capacitor Examples

 

The current UF category page already contains multiple live TDA-series products. Bringing several examples into the descriptive content helps connect category-level keywords with real purchasable specifications.

UF Part Number	Capacitance	Voltage	Tolerance	Key Mechanical Data
TDA2WK226G402GL5	22µF	450VDC	±10%	P 27.5mm; 32×37×22mm
TDA2NK306K424KD5	30µF	800VDC	±10%	P1 37.5mm; P2 20.3mm; 42×45×30mm
TDA3MK505G332GL5	5µF	1100VDC	±10%	P 27.5mm; 32×29×19mm
TDA3MK126K244KB5	12µF	1100VDC	±10%	P1 37.5mm; P2 10.2mm; 42×40×20mm
TDA3MK206K424KD5	20µF	1100VDC	±10%	P1 37.5mm; P2 20.3mm; approx. 42×45×30mm
TDA3MK406M204HD5	40µF	1100VDC	±10%	P1 52.5mm; P2 20.3mm; approx. 57×50×35mm

 

DC Link Film Capacitor Alternatives & Cross Reference

 

UF Capacitors THK and TDA DC-link film capacitor families can be evaluated as alternative sourcing options for applications currently using selected TDK/EPCOS, KEMET, Vishay, Panasonic and Cornell Dubilier DC-link capacitor series.

UF Capacitors	TDK / EPCOS	KEMET	Vishay	Panasonic	Cornell Dubilier
THK / TDA	B32778P	C4AK	MKP1848C	EZPV	BLH

 

Series-level cross-reference does not mean every individual part is pin-to-pin interchangeable. Before approving a replacement, compare capacitance, rated voltage, RMS current, ESR, dimensions, terminal spacing, temperature rating and lifetime requirements.

 

DC Link Film Capacitor vs Aluminum Electrolytic Capacitor

 

Film and aluminum electrolytic capacitors can both be used in DC-bus systems, but their strengths differ. The correct choice depends on required capacitance, voltage, ripple current, space, lifetime and cost.

 

Feature	Polypropylene DC Link Film Capacitor	Aluminum Electrolytic Capacitor
ESR	Generally low	Generally higher, series dependent
Ripple Current	Strong for high-current/high-frequency use	Application and series dependent
Polarity	Non-polar film construction	Polarized
High-Frequency Behavior	Strong	More limited relative to film
Aging Mechanism	No liquid electrolyte	Electrolyte aging is a key life mechanism
Capacitance Density	Lower	Higher
Typical Strength	High ripple current, low loss, long service-life potential	High bulk capacitance and energy storage density

 

Frequently Asked Questions

What is a DC link capacitor?

A DC link capacitor is connected across the intermediate DC bus of a power converter. It smooths DC-bus voltage, absorbs ripple current and supplies short-duration energy between converter stages.

What dielectric is commonly used in DC link film capacitors?

Metallized polypropylene is widely used because of its low dielectric loss, self-healing capability and suitability for high-voltage, high-ripple-current applications.

What voltage range does UF offer for DC link film capacitors?

UF's current TDA datasheet specifies approximately 450VDC to 1200VDC, depending on capacitance and part number.

What capacitance range does the UF TDA series cover?

The current UF TDA catalog lists approximately 1.0µF to 170µF.

Are DC link capacitors used in solar inverters?

Yes. They are commonly used on the intermediate DC bus of photovoltaic inverters to reduce ripple and stabilize DC voltage before the inverter switching stage.

Why is low ESR important in a DC link capacitor?

Lower ESR reduces internal power loss and heat generated by ripple current, improving thermal performance and helping the capacitor operate within its design limits.

How do I choose the capacitance of a DC link capacitor?

Capacitance depends on DC-bus voltage, allowable ripple, converter power, topology, load transients and switching conditions. It should be calculated from the actual circuit.

Can UF customize a DC link capacitor?

UF can evaluate customized capacitance, voltage, dimensions and terminal configurations according to project requirements.

Can UF replace TDK, KEMET or Vishay DC link capacitors?

UF THK and TDA series can be evaluated as alternative sourcing options for selected TDK/EPCOS, KEMET, Vishay and other DC-link capacitor families. Exact part-level compatibility must be confirmed through electrical and mechanical comparison.

 

Need a DC Link Capacitor for Your Inverter or Power Converter?

UF Capacitors supplies standard and customized metallized polypropylene DC-link film capacitors for industrial inverters, renewable-energy systems and high-power conversion equipment.

To recommend a suitable DC-link capacitor, provide:

 

• Required capacitance
• DC bus voltage
• RMS ripple current
• Switching frequency
• Maximum ambient temperature
• Size limitations
• Terminal / pin configuration
• Annual quantity

UF engineering can then recommend an existing TDA / THK part or evaluate a customized DC-link capacitor design.